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#include "qrhi_p.h"
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#include "qrhirsh_p.h"
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#include <qmath.h>

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#include "qrhinull_p.h"
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#ifndef QT_NO_OPENGL
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#include "qrhigles2_p.h"
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#endif
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#if QT_CONFIG(vulkan)
#include "qrhivulkan_p.h"
#endif
#ifdef Q_OS_WIN
#include "qrhid3d11_p.h"
#endif
#ifdef Q_OS_DARWIN
#include "qrhimetal_p.h"
#endif

QT_BEGIN_NAMESPACE

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/*!
    \class QRhi
    \inmodule QtRhi
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    \brief Accelerated 2D/3D graphics API abstraction.
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     QRhi is an abstraction for hardware accelerated graphics APIs, such as,
     \l{https://www.khronos.org/opengl/}{OpenGL},
     \l{https://www.khronos.org/opengles/}{OpenGL ES},
     \l{https://docs.microsoft.com/en-us/windows/desktop/direct3d}{Direct3D},
     \l{https://developer.apple.com/metal/}{Metal}, and
     \l{https://www.khronos.org/vulkan/}{Vulkan}.

    Each QRhi instance is backed by a backend for a specific graphics API. The
    selection of the backend is a run time choice and is up to the application
    or library that creates the QRhi instance. Some backends are available on
    multiple platforms (OpenGL, Vulkan, Null), while APIs specific to a given
    platform are only available when running on the platform in question (Metal
    on macOS/iOS/tvOS, Direct3D on Windows).

    \section2 Design Fundamentals

    A QRhi cannot be instantiated directly. Instead, use the create()
    function. Delete the QRhi instance normally to release the graphics device.

    \section3 Resources

    Instances of classes deriving from QRhiResource, such as, QRhiBuffer,
    QRhiTexture, etc., encapsulate zero, one, or more native graphics
    resources. Instances of such classes are always created via the \c new
    functions of the QRhi, such as, newBuffer(), newTexture(),
    newTextureRenderTarget(), newSwapChain().

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    \badcode
        vbuf = rhi->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(vertexData));
        if (!vbuf->build()) { error }
        ...
        vbuf->releaseAndDestroy();
    \endcode

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    \list

    \li The returned value from both create() and functions like newBuffer() is
    owned by the caller.

    \li Unlike QRhi, subclasses of QRhiResource should not be destroyed
    directly via delete without calling QRhiResource::release(). The typical
    approach is to call QRhiResource::releaseAndDestroy(). This is equivalent
    to QRhiResource::release() followed by \c delete.

    \li Just creating a QRhiResource subclass never allocates or initalizes any
    native resources. That is only done when calling the \c build function of a
    subclass, for example, QRhiBuffer::build() or QRhiTexture::build().

    \li The exception is
    QRhiTextureRenderTarget::newCompatibleRenderPassDescriptor() and
    QRhiSwapChain::newCompatibleRenderPassDescriptor(). There is no \c build
    operation for these and the returned object is immediately active.

    \li The resource objects themselves are treated as immutable: once a
    resource is built, changing any parameters via the setters, such as,
    QRhiTexture::setPixelSize(), has no effect, unless the underlying native
    resource is released and \c build is called again. See more about resource
    reuse in the sections below.

    \li The underlying native resources are scheduled for releasing by calling
    QRhiResource::release(). Backends often queue release requests and defer
    executing them to an unspecified time, this is hidden from the
    applications. This way applications do not have to worry about releasing a
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    native resource that may still be in use by an in-flight frame.

    \li Note that this does not mean that resources can freely be released
    within a frame (that is, in a
    \l{QRhiCommandBuffer::beginFrame()}{beginFrame()} -
    \l{QRhiCommandBuffer::endFrame()}{endFrame()} section). As a general rule,
    all referenced QRhiResource objects must stay unchanged until the frame is
    submitted by calling \l{QRhiCommandBuffer::endFrame()}{endFrame()}.
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    \endlist

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    \section3 Command buffers and defered command execution

    Regardless of the design and capabilities of the underlying graphics API,
    all QRhi backends implement some level of command buffers. No
    QRhiCommandBuffer function issues any native bind or draw command (such as,
    \c glDrawElements) directly. Commands are always recorded in a queue,
    either native or provided by the QRhi backend. The command buffer is
    submitted, and so execution starts only upon QRhi::endFrame() or
    QRhi::finish().

    The defered nature has consequences for some types of objects. For example,
    writing to a dynamic buffer multiple times within a frame, in case such
    buffers are backed by host-visible memory, will result in making the
    results of all writes are visible to all draw calls in the command buffer
    of the frame, regardless of when the dynamic buffer update was recorded
    relative to a draw call.

    Furthermore, instances of QRhiResource subclasses must be treated immutable
    within a frame in which they are referenced in any way. Create or rebuild
    all resources upfront, before starting to record commands for the next
    frame. Reusing a QRhiResource instance within a frame (by rebuilding it and
    then referencing it again in the same \c{beginFrame - endFrame} section)
    should be avoided as it may lead to unexpected results, depending on the
    backend. As a general rule, all referenced QRhiResource objects must stay
    unchanged until the frame is submitted by calling
    \l{QRhiCommandBuffer::endFrame()}{endFrame()}.

    Unlike APIs like OpenGL, upload and copy type of commands cannot be mixed
    with draw commands. The typical renderer will involve a sequence similar to
    the following: \c{(re)build resources} - \c{begin frame} - \c{record
    uploads and copies} - \c{start renderpass} - \c{record draw calls} - \c{end
    renderpass} - \c{end frame}. Recording copy type of operations happens via
    QRhiResourceUpdateBatch. Such operations are committed typically on
    \l{QRhiCommandBuffer::beginPass()}{beginPass()}.

    When working with legacy rendering engines designed for OpenGL, the
    migration to QRhi often involves redesigning from having a single \c render
    step (that performs copies and uploads, clears buffers, and issues draw
    calls, all mixed together) to a clearly separated, two phase \c prepare -
    \c render setup where the \c render step only starts a renderpass and
    records draw calls, while all resource creation and queuing of updates,
    uploads and copies happens beforehand, in the \c prepare step.
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    \section3 Resource reuse

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    From the user's point of view a QRhiResource is reusable immediately after
    calling QRhiResource::release(). With the exception of swapchains, calling
    \c build() on an already built object does an implicit \c release(). This
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    provides a handy shortcut to reuse a QRhiResource instance with different
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    parameters, with a new native graphics object underneath.
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    The importance of reusing the same object lies in the fact that some
    objects reference other objects: for example, a QRhiShaderResourceBindings
    can reference QRhiBuffer, QRhiTexture, and QRhiSampler instances. If now
    one of these buffers need to be resized or a sampler parameter needs
    changing, destroying and creating a whole new QRhiBuffer or QRhiSampler
    would invalidate all references to the old instance. By just changing the
    appropriate parameters via QRhiBuffer::setSize() or similar and then
    calling QRhiBuffer::build(), everything works as expected and there is no
    need to touch the QRhiShaderResourceBindings at all, even though there is a
    good chance that under the hood the QRhiBuffer is now backed by a whole new
    native buffer.

    \badcode
        ubuf = rhi->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, 256);
        ubuf->build();

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        srb = rhi->newShaderResourceBindings()
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        srb->setBindings({
            QRhiShaderResourceBinding::uniformBuffer(0, QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage, ubuf)
        });
        srb->build();

        ...

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        // now in a later frame we need to grow the buffer to a larger size
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        ubuf->setSize(512);
        ubuf->build(); // same as ubuf->release(); ubuf->build();

        // that's it, srb needs no changes whatsoever
    \endcode

    \section3 Pooled objects

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    In addition to resources, there are pooled objects as well, such as,
    QRhiResourceUpdateBatch. An instance is retrieved via a \c next function,
    such as, nextResourceUpdateBatch(). The caller does not own the returned
    instance in this case. The only valid way of operating here is calling
    functions on the QRhiResourceUpdateBatch and then passing it to
    QRhiCommandBuffer::beginPass() or QRhiCommandBuffer::endPass(). These
    functions take care of returning the batch to the pool. Alternatively, a
    batch can be "canceled" and returned to the pool without processing by
    calling QRhiResourceUpdateBatch::release().
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    A typical pattern is thus:

    \badcode
        QRhiResourceUpdateBatch *resUpdates = rhi->nextResourceUpdateBatch();
        ...
        resUpdates->updateDynamicBuffer(ubuf, 0, 64, mvp.constData());
        if (!image.isNull()) {
            resUpdates->uploadTexture(texture, image);
            image = QImage();
        }
        ...
        QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
        cb->beginPass(swapchain->currentFrameRenderTarget(), clearCol, clearDs, resUpdates);
    \endcode

    \section3 Swapchain specifics

    QRhiSwapChain features some special semantics due to the peculiar nature of
    swapchains.

    \list

    \li It has no \c build but rather a QRhiSwapChain::buildOrResize().
    Repeatedly calling this function is \b not the same as calling
    QRhiSwapChain::release() followed by QRhiSwapChain::buildOrResize(). This
    is because swapchains often have ways to handle the case where buffers need
    to be resized in a manner that is more efficient than a brute force
    destroying and recreating from scratch.

    \li An active QRhiSwapChain must be released by calling
    QRhiSwapChain::release() whenever the targeted QWindow sends the
    QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed event. It should not be
    postponed since releasing the swapchain may become problematic when the
    native window is not around anymore (e.g. because the QPlatformWindow got
    destroyed already when getting a QWindow::close())

    \endlist

    \section3 Ownership

    The general rule is no ownership transfer. Creating a QRhi with an already
    existing graphics device does not mean the QRhi takes ownership of the
    device object. Similarly, ownership is not given away when a device or
    texture object is "exported" via QRhi::nativeHandles() or
    QRhiTexture::nativeHandles(). Most importantly, passing pointers in structs
    and via setters does not transfer ownership.

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    \section3 Threading and resource sharing
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    A QRhi instance can be created and used on any thread but all usage must be
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    limited to that one single thread.
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    When it comes to externally created native objects, such as OpenGL contexts
    passed in via QRhiGles2NativeHandles, it is up to the application to ensure
    they are not misused by other threads.

    By default any QRhiResource created from one QRhi must only be used with
    that one QRhi and must be released before the QRhi is destroyed. This rule
    is relaxed when a QRhi is created with an associated
    QRhiResourceSharingHost. From then on any QRhiResource that reports \c true
    from \l{QRhiResource::isShareable()}{isShareable()} is usable with other
    QRhi instances as well, as long as they are associated with the same
    QRhiResourceSharingHost. Resources can also outlive their creating QRhi in
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    this case, as long as there is at least one QRhi left in the sharing group.
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    \note Support for efficient concurrent access to shared resources from QRhi
    instances operating on different threads, especially when writing (for
    example, rendering to a texture) is involved, is limited for the time
    being. Neither GPU-GPU nor GPU-host synchronization facilities (such as,
    fences or events) are provided in the QRhi API at the moment. These may be
    introduced in the future.

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    \sa {Qt Shader Tools}, QRhiResourceSharingHost
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 */

/*!
    \enum QRhi::Implementation
    Describes which graphics API-specific backend gets used by a QRhi instance.

    \value Null
    \value Vulkan
    \value OpenGLES2
    \value D3D11
    \value Metal
 */

/*!
    \enum QRhi::Flag
    Describes what special features to enable.

    \value EnableProfiling Enables gathering timing (CPU, GPU) and resource
    (QRhiBuffer, QRhiTexture, etc.) information and additional metadata. See
    QRhiProfiler. Avoid enabling in production builds as it may involve a
    performance penalty.

    \value EnableDebugMarkers Enables debug marker groups. Without this frame
    debugging features like making debug groups and custom resource name
    visible in external GPU debugging tools will not be available and functions
    like QRhiCommandBuffer::debugMarkBegin() will become a no-op. Avoid
    enabling in production builds as it may involve a performance penalty.
 */

/*!
    \enum QRhi::FrameOpResult
    Describes the result of operations that can have a soft failure.

    \value FrameOpSuccess Success

    \value FrameOpError Unspecified error

    \value FrameOpSwapChainOutOfDate The swapchain is in an inconsistent state
    internally. This can be recoverable by attempting to repeat the operation
    (such as, beginFrame()) later.

    \value FrameOpDeviceLost The graphics device was lost. This can be
    recoverable by attempting to repeat the operation (such as, beginFrame())
    and releasing and reinitializing all objects backed by native graphics
    resources.
 */

/*!
    \enum QRhi::Feature
    Flag values to indicate what features are supported by the backend currently in use.

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    \value MultisampleTexture Indicates that textures with a sample count larger
    than 1 are supported.
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    \value MultisampleRenderBuffer Indicates that renderbuffers with a sample
    count larger than 1 are supported.
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    \value DebugMarkers Indicates that debug marker groups (and so
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    QRhiCommandBuffer::debugMarkBegin()) are supported.

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    \value Timestamps Indicates that command buffer timestamps are supported.
    Relevant for QRhiProfiler::gpuFrameTimes().
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    \value Instancing Indicates that instanced drawing is supported.
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    \value CustomInstanceStepRate Indicates that instance step rates other than
    1 are supported.
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    \value PrimitiveRestart Indicates that restarting the assembly of
    primitives when encountering an index value of 0xFFFF
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    (\l{QRhiCommandBuffer::IndexUInt16}{IndexUInt16}) or 0xFFFFFFFF
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    (\l{QRhiCommandBuffer::IndexUInt32}{IndexUInt32}) is enabled, for certain
    primitive topologies at least. QRhi will try to enable this with all
    backends, but in some cases it will not be supported. Dynamically
    controlling primitive restart is not possible since with some APIs
    primitive restart with a fixed index is always on. Applications must assume
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    that whenever this feature is reported as supported, the above mentioned
    index values \c may be treated specially, depending on the topology. The
    only two topologies where primitive restart is guaranteed to behave
    identically across backends, as long as this feature is reported as
    supported, are \l{QRhiGraphicsPipeline::LineStrip}{LineStrip} and
    \l{QRhiGraphicsPipeline::TriangleStrip}{TriangleStrip}.
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    \value GeometryShaders Indicates that geometry shaders are supported.

    \value TessellationShaders Indicates that tessellation control and
    evaluation shaders are supported.
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    \value NonDynamicUniformBuffers Indicates that creating buffers with the
    usage \l{QRhiBuffer::UniformBuffer}{UniformBuffer} and the types
    \l{QRhiBuffer::Immutable}{Immutable} or \l{QRhiBuffer::Static}{Static} is
    supported. When reported as unsupported, uniform (constant) buffers must be
    created as \l{QRhiBuffer::Dynamic}{Dynamic}. (which is recommended
    regardless)
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    \value NonFourAlignedEffectiveIndexBufferOffset Indicates that effective
    index buffer offsets (\c{indexOffset + firstIndex * indexComponentSize})
    that are not 4 byte aligned are supported. When not supported, attempting
    to issue a \l{QRhiCommandBuffer::drawIndexed()}{drawIndexed()} with a
    non-aligned effective offset may lead to unspecified behavior.
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    \value NPOTTextureRepeat Indicates that the \l{QRhiSampler::Repeat}{Repeat}
    mode is supported for textures with a non-power-of-two size.
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 */

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/*!
    \enum QRhi::BeginFrameFlag
    Flag values for QRhi::beginFrame()
 */

/*!
    \enum QRhi::EndFrameFlag
    Flag values for QRhi::endFrame()

    \value SkipPresent Specifies that no present command is to be queued or no
    swapBuffers call is to be made. This way no image is presented. Generating
    multiple frames with all having this flag set is not recommended (except,
    for example, for benchmarking purposes - but keep in mind that backends may
    behave differently when it comes to waiting for command completion without
    presenting so the results are not comparable between them)
 */

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/*!
    \enum QRhi::ResourceSizeLimit
    Describes the resource limit to query.

    \value TextureSizeMin Minimum texture width and height. This is typically
    1. The minimum texture size is handled gracefully, meaning attempting to
    create a texture with an empty size will instead create a texture with the
    minimum size.

    \value TextureSizeMax Maximum texture width and height. This depends on the
    graphics API and sometimes the platform or implementation as well.
    Typically the value is in the range 4096 - 16384. Attempting to create
    textures larger than this is expected to fail.
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 */

/*!
    \class QRhiInitParams
    \inmodule QtRhi
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    \brief Base class for backend-specific initialization parameters.
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    Contains fields that are relevant to all backends.

    \l resourceSharingHost is set to null by default. Setting it to an actual
    QRhiResourceSharingHost instance is optional. When set, it causes the QRhi
    to share either the graphics device, or, in case of OpenGL, use a context
    that shares resources, with all other QRhi instances that have the same
    QRhiResourceSharingHost set in their QRhiInitParams. This makes the
    underlying graphics resources of QRhiResource subclasses such as
    QRhiTexture visible to all the QRhi instances that use the same
    QRhiResourceSharingHost.
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    \sa QRhiResource::isShareable()
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 */

/*!
    \class QRhiColorClearValue
    \inmodule QtRhi
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    \brief Specifies a clear color for a color buffer.
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 */

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/*!
    Constructs a color clear value with \c{(0, 0, 0, 1)} (opaque black).
 */
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QRhiColorClearValue::QRhiColorClearValue()
    : m_rgba(0, 0, 0, 1)
{
}

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/*!
    Constructs a color clear value with the floating point color components
    (\c{0.0f - 1.0f}) specified in \a c.
  */
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QRhiColorClearValue::QRhiColorClearValue(const QVector4D &c)
    : m_rgba(c)
{
}

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/*!
    Constructs a color clear value with the floating point color components
    (\c{0.0f - 1.0f}) specified in \a r, \a g, \a b, and \a a.
 */
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QRhiColorClearValue::QRhiColorClearValue(float r, float g, float b, float a)
    : m_rgba(r, g, b, a)
{
}

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/*!
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    \return \c true if the colors in the two QRhiColorClearValue objects \a a
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    and \a b are equal.

    \relates QRhiColorClearValue
 */
bool operator==(const QRhiColorClearValue &a, const QRhiColorClearValue &b) Q_DECL_NOTHROW
{
    return a.rgba() == b.rgba();
}

/*!
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    \return \c false if the colors in the two QRhiColorClearValue objects \a a
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    and \a b are equal; otherwise returns \c true.

    \relates QRhiColorClearValue
*/
bool operator!=(const QRhiColorClearValue &a, const QRhiColorClearValue &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiColorClearValue
 */
uint qHash(const QRhiColorClearValue &v, uint seed) Q_DECL_NOTHROW
{
    const QVector4D c = v.rgba();
    return qFloor((c.x() + c.y() + c.z() + c.w()) * 1000) + seed;
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiColorClearValue &v)
{
    QDebugStateSaver saver(dbg);
    const QVector4D c = v.rgba();
    dbg.nospace() << "QRhiColorClearValue(r=" << c.x()
                  << " g=" << c.y()
                  << " b=" << c.z()
                  << " a=" << c.w()
                  << ')';
    return dbg;
}
#endif

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/*!
    \class QRhiDepthStencilClearValue
    \inmodule QtRhi
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    \brief Specifies clear values for a depth or stencil buffer.
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 */

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/*!
    Constructs a depth/stencil clear value with depth clear value 1.0f and
    stencil clear value 0.
 */
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QRhiDepthStencilClearValue::QRhiDepthStencilClearValue()
    : m_d(1),
      m_s(0)
{
}

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/*!
    Constructs a depth/stencil clear value with depth clear value \a d and
    stencil clear value \a s.
 */
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QRhiDepthStencilClearValue::QRhiDepthStencilClearValue(float d, quint32 s)
    : m_d(d),
      m_s(s)
{
}

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/*!
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    \return \c true if the values in the two QRhiDepthStencilClearValue objects
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    \a a and \a b are equal.

    \relates QRhiDepthStencilClearValue
 */
bool operator==(const QRhiDepthStencilClearValue &a, const QRhiDepthStencilClearValue &b) Q_DECL_NOTHROW
{
    return a.depthClearValue() == b.depthClearValue()
            && a.stencilClearValue() == b.stencilClearValue();
}

/*!
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    \return \c false if the values in the two QRhiDepthStencilClearValue
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiDepthStencilClearValue
*/
bool operator!=(const QRhiDepthStencilClearValue &a, const QRhiDepthStencilClearValue &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiDepthStencilClearValue
 */
uint qHash(const QRhiDepthStencilClearValue &v, uint seed) Q_DECL_NOTHROW
{
    return seed * (qFloor(v.depthClearValue() * 100) + v.stencilClearValue());
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiDepthStencilClearValue &v)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QRhiDepthStencilClearValue(depth-clear=" << v.depthClearValue()
                  << " stencil-clear=" << v.stencilClearValue()
                  << ')';
    return dbg;
}
#endif

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/*!
    \class QRhiViewport
    \inmodule QtRhi
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    \brief Specifies a viewport rectangle.
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    Used with QRhiCommandBuffer::setViewport().

    \note QRhi assumes OpenGL-style viewport coordinates, meaning x and y are
    bottom-left.

    Typical usage is like the following:

    \badcode
      const QSize outputSizeInPixels = swapchain->currentPixelSize();
      const QRhiViewport viewport(0, 0, outputSizeInPixels.width(), outputSizeInPixels.height());
      cb->beginPass(swapchain->currentFrameRenderTarget(), { 0, 0, 0, 1 }, { 1, 0 });
      cb->setGraphicsPipeline(ps);
      cb->setViewport(viewport);
      ...
    \endcode

    \sa QRhiCommandBuffer::setViewport(), QRhi::clipSpaceCorrMatrix(), QRhiScissor
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 */

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/*!
    Constructs a viewport description with a default rectangle and depth range.
    The default depth range is 0.0f - 1.0f.

    \sa QRhi::clipSpaceCorrMatrix()
 */
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QRhiViewport::QRhiViewport()
    : m_rect(0, 0, 1280, 720),
      m_minDepth(0),
      m_maxDepth(1)
{
}

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/*!
    Constructs a viewport description with the rectangle specified by \a x, \a
    y, \a w, \a h and the depth range \a minDepth and \a maxDepth.

    \note x and y are assumed to be the bottom-left position.

    \sa QRhi::clipSpaceCorrMatrix()
 */
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QRhiViewport::QRhiViewport(float x, float y, float w, float h, float minDepth, float maxDepth)
    : m_rect(x, y, w, h),
      m_minDepth(minDepth),
      m_maxDepth(maxDepth)
{
}

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/*!
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    \return \c true if the values in the two QRhiViewport objects
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    \a a and \a b are equal.

    \relates QRhiViewport
 */
bool operator==(const QRhiViewport &a, const QRhiViewport &b) Q_DECL_NOTHROW
{
    return a.viewport() == b.viewport()
            && a.minDepth() == b.minDepth()
            && a.maxDepth() == b.maxDepth();
}

/*!
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    \return \c false if the values in the two QRhiViewport
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiViewport
*/
bool operator!=(const QRhiViewport &a, const QRhiViewport &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiViewport
 */
uint qHash(const QRhiViewport &v, uint seed) Q_DECL_NOTHROW
{
    const QVector4D r = v.viewport();
    return seed + r.x() + r.y() + r.z() + r.w() + qFloor(v.minDepth() * 100) + qFloor(v.maxDepth() * 100);
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiViewport &v)
{
    QDebugStateSaver saver(dbg);
    const QVector4D r = v.viewport();
    dbg.nospace() << "QRhiViewport(bottom-left-x=" << r.x()
                  << " bottom-left-y=" << r.y()
                  << " width=" << r.z()
                  << " height=" << r.w()
                  << " minDepth=" << v.minDepth()
                  << " maxDepth=" << v.maxDepth()
                  << ')';
    return dbg;
}
#endif

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/*!
    \class QRhiScissor
    \inmodule QtRhi
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    \brief Specifies a scissor rectangle.
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    Used with QRhiCommandBuffer::setScissor(). Setting a scissor rectangle is
    only possible with a QRhiGraphicsPipeline that has
    QRhiGraphicsPipeline::UsesScissor set.

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    \note QRhi assumes OpenGL-style scissor coordinates, meaning x and y are
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    bottom-left.

    \sa QRhiCommandBuffer::setScissor(), QRhiViewport
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 */

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/*!
    Constructs an empty scissor.
 */
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QRhiScissor::QRhiScissor()
{
}

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/*!
    Constructs a scissor with the rectangle specified by \a x, \a y, \a w, and
    \a h.

    \note x and y are assumed to be the bottom-left position.
 */
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QRhiScissor::QRhiScissor(int x, int y, int w, int h)
    : m_rect(x, y, w, h)
{
}
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/*!
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    \return \c true if the values in the two QRhiScissor objects
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    \a a and \a b are equal.

    \relates QRhiScissor
 */
bool operator==(const QRhiScissor &a, const QRhiScissor &b) Q_DECL_NOTHROW
{
    return a.scissor() == b.scissor();
}

/*!
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    \return \c false if the values in the two QRhiScissor
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiScissor
*/
bool operator!=(const QRhiScissor &a, const QRhiScissor &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiScissor
 */
uint qHash(const QRhiScissor &v, uint seed) Q_DECL_NOTHROW
{
    const QVector4D r = v.scissor();
    return seed + r.x() + r.y() + r.z() + r.w();
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiScissor &s)
{
    QDebugStateSaver saver(dbg);
    const QVector4D r = s.scissor();
    dbg.nospace() << "QRhiScissor(bottom-left-x=" << r.x()
                  << " bottom-left-y=" << r.y()
                  << " width=" << r.z()
                  << " height=" << r.w()
                  << ')';
    return dbg;
}
#endif

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/*!
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    \class QRhiVertexInputBinding
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    \inmodule QtRhi
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    \brief Describes a vertex input binding.
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    Specifies the stride (in bytes, must be a multiple of 4), the
    classification and optionally the instance step rate.

    As an example, assume a vertex shader with the following inputs:

    \badcode
        layout(location = 0) in vec4 position;
        layout(location = 1) in vec2 texcoord;
    \endcode

    Now let's assume also that 3 component vertex positions \c{(x, y, z)} and 2
    component texture coordinates \c{(u, v)} are provided in a non-interleaved
    format in a buffer (or separate buffers even). Definining two bindings
    could then be done like this:

    \badcode
        QRhiVertexInputLayout inputLayout;
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        inputLayout.setBindings({
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            { 3 * sizeof(float) },
            { 2 * sizeof(float) }
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        });
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    \endcode

    Only the stride is interesting here since instancing is not used. The
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    binding number is given by the index of the QRhiVertexInputBinding
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    element in the bindings vector of the QRhiVertexInputLayout.

    Once a graphics pipeline with this vertex input layout is bound, the vertex
    inputs could be set up like the following for drawing a cube with 36
    vertices, assuming we have a single buffer with first the positions and
    then the texture coordinates:

    \badcode
        cb->setVertexInput(0, { { cubeBuf, 0 }, { cubeBuf, 36 * 3 * sizeof(float) } });
    \endcode

    Note how the index defined by \c {startBinding + i}, where \c i is the
    index in the second argument of
    \l{QRhiCommandBuffer::setVertexInput()}{setVertexInput()}, matches the
    index of the corresponding entry in the \c bindings vector of the
    QRhiVertexInputLayout.

    \note the stride must always be a multiple of 4.

    \sa QRhiCommandBuffer::setVertexInput()
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 */

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/*!
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    \enum QRhiVertexInputBinding::Classification
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    Describes the input data classification.

    \value PerVertex Data is per-vertex
    \value PerInstance Data is per-instance
 */

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/*!
    Constructs an empty vertex input binding description.
 */
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QRhiVertexInputBinding::QRhiVertexInputBinding()
{
}

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/*!
    Constructs a vertex input binding description with the specified \a stride,
    classification \a cls, and instance step rate \a stepRate.

    \note \a stepRate other than 1 is only supported when
    QRhi::CustomInstanceStepRate is reported to be supported.
 */
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QRhiVertexInputBinding::QRhiVertexInputBinding(quint32 stride, Classification cls, int stepRate)
    : m_stride(stride),
      m_classification(cls),
      m_instanceStepRate(stepRate)
{
}

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/*!
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    \return \c true if the values in the two QRhiVertexInputBinding objects
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    \a a and \a b are equal.

    \relates QRhiVertexInputBinding
 */
bool operator==(const QRhiVertexInputBinding &a, const QRhiVertexInputBinding &b) Q_DECL_NOTHROW
{
    return a.stride() == b.stride()
            && a.classification() == b.classification()
            && a.instanceStepRate() == b.instanceStepRate();
}

/*!
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    \return \c false if the values in the two QRhiVertexInputBinding
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiVertexInputBinding
*/
bool operator!=(const QRhiVertexInputBinding &a, const QRhiVertexInputBinding &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiVertexInputBinding
 */
uint qHash(const QRhiVertexInputBinding &v, uint seed) Q_DECL_NOTHROW
{
    return seed + v.stride() + v.classification();
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiVertexInputBinding &b)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QRhiVertexInputBinding(stride=" << b.stride()
                  << " cls=" << b.classification()
                  << " step-rate=" << b.instanceStepRate()
                  << ')';
    return dbg;
}
#endif

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/*!
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    \class QRhiVertexInputAttribute
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    \inmodule QtRhi
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    \brief Describes a single vertex input element.
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    The members specify the binding number, location, format, and offset for a
    single vertex input element.

    \note For HLSL it is assumed that the vertex shader uses
    \c{TEXCOORD<location>} as the semantic for each input. Hence no separate
    semantic name and index.

    As an example, assume a vertex shader with the following inputs:

    \badcode
        layout(location = 0) in vec4 position;
        layout(location = 1) in vec2 texcoord;
    \endcode

    Now let's assume that we have 3 component vertex positions \c{(x, y, z)}
    and 2 component texture coordinates \c{(u, v)} are provided in a
    non-interleaved format in a buffer (or separate buffers even). Once two
    bindings are defined, the attributes could be specified as:

    \badcode
        QRhiVertexInputLayout inputLayout;
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        inputLayout.setBindings({
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            { 3 * sizeof(float) },
            { 2 * sizeof(float) }
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        });
        inputLayout.setAttributes({
            { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
            { 1, 1, QRhiVertexInputAttribute::Float2, 0 }
        });
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    \endcode

    Once a graphics pipeline with this vertex input layout is bound, the vertex
    inputs could be set up like the following for drawing a cube with 36
    vertices, assuming we have a single buffer with first the positions and
    then the texture coordinates:

    \badcode
        cb->setVertexInput(0, { { cubeBuf, 0 }, { cubeBuf, 36 * 3 * sizeof(float) } });
    \endcode

    When working with interleaved data, there will typically be just one
    binding, with multiple attributes refering to that same buffer binding
    point:

    \badcode
        QRhiVertexInputLayout inputLayout;
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        inputLayout.setBindings({
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            { 5 * sizeof(float) }
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        });
        inputLayout.setAttributes({
            { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
            { 0, 1, QRhiVertexInputAttribute::Float2, 3 * sizeof(float) }
        });
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    \endcode

    and then:

    \badcode
        cb->setVertexInput(0, { { interleavedCubeBuf, 0 } });
    \endcode

    \sa QRhiCommandBuffer::setVertexInput()
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 */

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/*!
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    \enum QRhiVertexInputAttribute::Format
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    Specifies the type of the element data.

    \value Float4 Four component float vector
    \value Float3 Three component float vector
    \value Float2 Two component float vector
    \value Float Float
    \value UNormByte4 Four component normalized unsigned byte vector
    \value UNormByte2 Two component normalized unsigned byte vector
    \value UNormByte Normalized unsigned byte
 */

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/*!
    Constructs an empty vertex input attribute description.
 */
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QRhiVertexInputAttribute::QRhiVertexInputAttribute()
{
}

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/*!
    Constructs a vertex input attribute description with the specified \a
    binding number, \a location, \a format, and \a offset.
 */
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QRhiVertexInputAttribute::QRhiVertexInputAttribute(int binding, int location, Format format, quint32 offset)
    : m_binding(binding),
      m_location(location),
      m_format(format),
      m_offset(offset)
{
}

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/*!
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    \return \c true if the values in the two QRhiVertexInputAttribute objects
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    \a a and \a b are equal.

    \relates QRhiVertexInputAttribute
 */
bool operator==(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b) Q_DECL_NOTHROW
{
    return a.binding() == b.binding()
            && a.location() == b.location()
            && a.format() == b.format()
            && a.offset() == b.offset();
}

/*!
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    \return \c false if the values in the two QRhiVertexInputAttribute
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiVertexInputAttribute
*/
bool operator!=(const QRhiVertexInputAttribute &a, const QRhiVertexInputAttribute &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiVertexInputAttribute
 */
uint qHash(const QRhiVertexInputAttribute &v, uint seed) Q_DECL_NOTHROW
{
    return seed + v.binding() + v.location() + v.format() + v.offset();
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiVertexInputAttribute &a)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QRhiVertexInputAttribute(binding=" << a.binding()
                  << " location=" << a.location()
                  << " format=" << a.format()
                  << " offset=" << a.offset()
                  << ')';
    return dbg;
}
#endif

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/*!
    \class QRhiVertexInputLayout
    \inmodule QtRhi
    \brief Describes the layout of vertex inputs consumed by a vertex shader.
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    The vertex input layout is defined by the collections of
    QRhiVertexInputBinding and QRhiVertexInputAttribute.
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 */

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/*!
    Constructs an empty vertex input layout description.
 */
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QRhiVertexInputLayout::QRhiVertexInputLayout()
{
}

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/*!
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    \return \c true if the values in the two QRhiVertexInputLayout objects
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    \a a and \a b are equal.

    \relates QRhiVertexInputLayout
 */
bool operator==(const QRhiVertexInputLayout &a, const QRhiVertexInputLayout &b) Q_DECL_NOTHROW
{
    return a.bindings() == b.bindings()
            && a.attributes() == b.attributes();
}

/*!
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    \return \c false if the values in the two QRhiVertexInputLayout
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiVertexInputLayout
*/
bool operator!=(const QRhiVertexInputLayout &a, const QRhiVertexInputLayout &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiVertexInputLayout
 */
uint qHash(const QRhiVertexInputLayout &v, uint seed) Q_DECL_NOTHROW
{
    return qHash(v.bindings(), seed) + qHash(v.attributes(), seed);
}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiVertexInputLayout &v)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QRhiVertexInputLayout(bindings=" << v.bindings()
                  << " attributes=" << v.attributes()
                  << ')';
    return dbg;
}
#endif

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/*!
    \class QRhiGraphicsShaderStage
    \inmodule QtRhi
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    \brief Specifies the type and the shader code for a shader stage in the graphics pipeline.
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    \note Some backends only support a subset of the stages. Use
    QRhi::isFeatureSupported() to query for support at runtime. For example,
    Metal has no geometry shader support, while the OpenGL 2.x backend only
    supports the vertex and fragment stages.
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 */

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/*!
    \enum QRhiGraphicsShaderStage::Type
    Specifies the type of the shader stage.

    \value Vertex Vertex stage
    \value Fragment Fragment (pixel) stage
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    \value Geometry Geometry stage
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    \value TessellationControl Tessellation control (hull) stage
    \value TessellationEvaluation Tessellation evaluation (domain) stage
 */

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/*!
    Constructs an empty shader stage description.
 */
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QRhiGraphicsShaderStage::QRhiGraphicsShaderStage()
{
}
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/*!
    Constructs a shader stage description with the \a type of the stage and the
    \a shader.
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    The shader variant \a v defaults to QBakedShaderKey::StandardShader. A
    QBakedShader pack contains multiple source and binary versions of a shader.
    In addition, it can also contain variants of the shader with slightly
    modified code. \a v can then be used to select the desired variant.
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 */
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QRhiGraphicsShaderStage::QRhiGraphicsShaderStage(Type type, const QBakedShader &shader, QBakedShaderKey::ShaderVariant v)
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    : m_type(type),
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      m_shader(shader),
      m_shaderVariant(v)
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{
}
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/*!
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    \return \c true if the values in the two QRhiGraphicsShaderStage objects
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    \a a and \a b are equal.

    \relates QRhiGraphicsShaderStage
 */
bool operator==(const QRhiGraphicsShaderStage &a, const QRhiGraphicsShaderStage &b) Q_DECL_NOTHROW
{
    return a.type() == b.type()
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            && a.shader() == b.shader()
            && a.shaderVariant() == b.shaderVariant();
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}

/*!
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    \return \c false if the values in the two QRhiGraphicsShaderStage
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    objects \a a and \a b are equal; otherwise returns \c true.

    \relates QRhiGraphicsShaderStage
*/
bool operator!=(const QRhiGraphicsShaderStage &a, const QRhiGraphicsShaderStage &b) Q_DECL_NOTHROW
{
    return !(a == b);
}

/*!
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    \return the hash value for \a v, using \a seed to seed the calculation.
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    \relates QRhiGraphicsShaderStage
 */
uint qHash(const QRhiGraphicsShaderStage &v, uint seed) Q_DECL_NOTHROW
{
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    return v.type() + qHash(v.shader(), seed) + v.shaderVariant();
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}

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#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QRhiGraphicsShaderStage &s)
{
    QDebugStateSaver saver(dbg);
    dbg.nospace() << "QRhiGraphicsShaderStage(type=" << s.type()
                  << " shader=" << s.shader()
                  << " variant=" << s.shaderVariant()
                  << ')';
    return dbg;
}
#endif

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/*!
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    \class QRhiColorAttachment
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    \inmodule QtRhi
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    \brief Describes the a single color attachment of a render target.

    A color attachment is either a QRhiTexture or a QRhiRenderBuffer. The
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    former, when texture() is set, is used in most cases.
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    \note texture() and renderBuffer() cannot be both set (be non-null at the
    same time).
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    Setting renderBuffer instead is recommended only when multisampling is
    needed. Relying on QRhi::MultisampleRenderBuffer is a better choice than
    QRhi::MultisampleTexture in practice since the former is available in more
    run time configurations (e.g. when running on OpenGL ES 3.0 which has no
    support for multisample textures, but does support multisample
    renderbuffers).

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    When targeting a non-multisample texture, the layer() and level()
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    indicate the targeted layer (face index \c{0-5} for cubemaps) and mip
    level.

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    When texture() or renderBuffer() is multisample, resolveTexture() can be
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    set optionally. When set, samples are resolved automatically into that
    (non-multisample) texture at the end of the render pass. When rendering
    into a multisample renderbuffers, this is the only way to get resolved,
    non-multisample content out of them. Multisample textures allow sampling in
    shaders so for them this is just one option.

    \note when resolving is enabled, the multisample data may not be written
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    out at all. This means that the multisample texture() must not be used
    afterwards with shaders for sampling when resolveTexture() is set.
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 */

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/*!
    Constructs an empty color attachment description.
 */
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QRhiColorAttachment::QRhiColorAttachment()
{
}

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/*!
    Constructs a color attachment description that specifies \a texture as the
    associated color buffer.
 */
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QRhiColorAttachment::QRhiColorAttachment(QRhiTexture *texture)
    : m_texture(texture)
{
}

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/*!
    Constructs a color attachment description that specifies \a renderBuffer as
    the associated color buffer.
 */
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QRhiColorAttachment::QRhiColorAttachment(QRhiRenderBuffer *renderBuffer)
    : m_renderBuffer(renderBuffer)
{
}

/*!
    \class QRhiTextureRenderTargetDescription
    \inmodule QtRhi
    \brief Describes the color and depth or depth/stencil attachments of a render target.

    A texture render target has zero or more textures as color attachments,
    zero or one renderbuffer as combined depth/stencil buffer or zero or one
    texture as depth buffer.

    \note depthStencilBuffer() and depthTexture() cannot be both set (cannot be
    non-null at the same time).
 */

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/*!
    Constructs an empty texture render target description.
 */
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QRhiTextureRenderTargetDescription::QRhiTextureRenderTargetDescription()
{
}

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/*!
    Constructs a texture render target description with one attachment
    described by \a colorAttachment.
 */
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QRhiTextureRenderTargetDescription::QRhiTextureRenderTargetDescription(const QRhiColorAttachment &colorAttachment)
{
    m_colorAttachments.append(colorAttachment);
}

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/*!
    Constructs a texture render target description with two attachments, a
    color attachment described by \a colorAttachment, and a depth/stencil
    attachment with \a depthStencilBuffer.
 */
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QRhiTextureRenderTargetDescription::QRhiTextureRenderTargetDescription(const QRhiColorAttachment &colorAttachment,
                                                                       QRhiRenderBuffer *depthStencilBuffer)
    : m_depthStencilBuffer(depthStencilBuffer)
{
    m_colorAttachments.append(colorAttachment);
}

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/*!
    Constructs a texture render target description with two attachments, a
    color attachment described by \a colorAttachment, and a depth attachment
    with \a depthTexture.

    \note \a depthTexture must have a suitable format, such as QRhiTexture::D16
    or QRhiTexture::D32.
 */
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QRhiTextureRenderTargetDescription::QRhiTextureRenderTargetDescription(const QRhiColorAttachment &colorAttachment,
                                                                       QRhiTexture *depthTexture)
    : m_depthTexture(depthTexture)
{
    m_colorAttachments.append(colorAttachment);
}

/*!
    \class QRhiTextureMipLevel
    \inmodule QtRhi
    \brief Describes one mip level in a layer in a texture upload operation.

    The source content is specified either as a QImage or as a raw blob. The
    former is only allowed for uncompressed textures, while the latter is only
    supported for compressed ones.

    \note image() and compressedData() cannot be both set at the same time.

    destinationTopLeft() specifies the top-left corner of the target
    rectangle. Defaults to (0, 0).

    An empty sourceSize() (the default) indicates that size is assumed to be
    the size of the subresource. For uncompressed textures this implies that
    the size of the source image() must match the subresource. For compressed
    textures sufficient amount of data must be provided in compressedData().

    \note With compressed textures the first upload must always match the
    subresource size due to graphics API limitations with some backends.

    sourceTopLeft() is is only supported for uncompressed textures, and
    specifies the top-left corner of the source rectangle.

    \note Setting sourceSize() or sourceTopLeft() may trigger a QImage copy
    internally, depending on the format and the backend.
 */

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/*!
    Constructs an empty mip level description.
 */
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QRhiTextureMipLevel::QRhiTextureMipLevel()
{
}

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/*!
    Constructs a mip level description with a \a image.

    The \l{QImage::size()}{size} of \a image must match the size of the mip
    level. For level 0 that is the \l{QRhiTexture::pixelSize()}{texture size}.

    The bit depth of \a image must be compatible with the
    \l{QRhiTexture::Format}{texture format}.

    To describe a partial upload, call setSourceSize(), setSourceTopLeft(), or
    setDestinationTopLeft() afterwards.
 */
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QRhiTextureMipLevel::QRhiTextureMipLevel(const QImage &image)
    : m_image(image)
{
}

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/*!
    Constructs a mip level description suitable for compressed textures. The
    compressed data is specified in \a compressedData.
 */
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QRhiTextureMipLevel::QRhiTextureMipLevel(const QByteArray &compressedData)
    : m_compressedData(compressedData)
{
}

/*!
    \class QRhiTextureLayer
    \inmodule QtRhi
    \brief Describes one layer (face for cubemaps) in a texture upload operation.
 */

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/*!
    Constructs an empty texture layer description.
 */
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QRhiTextureLayer::QRhiTextureLayer()
{
}

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/*!
    Constructs a texture layer description with the specified list of \a
    mipImages.
 */
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QRhiTextureLayer::QRhiTextureLayer(const QVector<QRhiTextureMipLevel> &mipImages)
    : m_mipImages(mipImages)
{
}

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/*!
    \class QRhiTextureUploadDescription
    \inmodule QtRhi
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    \brief Describes a texture upload operation.
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    Used with QRhiResourceUpdateBatch::uploadTexture(). That function has two
    variants: one taking a QImage and one taking a
    QRhiTextureUploadDescription. The former is a convenience version,
    internally creating a QRhiTextureUploadDescription with a single layer and
    a single image in that layer. However, when cubemaps, pre-generated mip
    images, or compressed textures are involved, applications will have to work
    directly with this class instead.

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    \note Cubemaps have one layer for each of the six faces in the order +X,
    -X, +Y, -Y, +Z, -Z.
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    For example, specifying the faces of a cubemap could look like the following:

    \badcode
        QImage faces[6];
        ...
        QVector<QRhiTextureLayer> layers;
        for (int i = 0; i < 6; ++i)
          layers.append(QRhiTextureLayer({ QRhiTextureMipLevel(faces[i]) });
        QRhiTextureUploadDescription desc(layers);
        resourceUpdates->uploadTexture(texture, desc);
    \endcode

    Another example that specifies mip images for a compressed texture:

    \badcode
        QVector<QRhiTextureMipLevel> mipImages;
        const int mipCount = rhi->mipLevelsForSize(compressedTexture->pixelSize());
        for (int level = 0; level < mipCount; ++level) {
            const QByteArray compressedDataForLevel = ...
            mipImages.append(QRhiTextureMipLevel(compressedDataForLevel));
        }
        QRhiTextureLayer layer(mipImages);
        QRhiTextureUploadDescription desc({ layer });
        resourceUpdates->uploadTexture(compressedTexture, desc);
    \endcode
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 */

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/*!
    Constructs an empty texture upload description.
 */
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QRhiTextureUploadDescription::QRhiTextureUploadDescription()
{
}
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/*!
    Constructs a texture upload description with the specified list of \a
    layers.
 */
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QRhiTextureUploadDescription::QRhiTextureUploadDescription(const QVector<QRhiTextureLayer> &layers)
    : m_layers(layers)
{
}
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/*!
    \class QRhiTextureCopyDescription
    \inmodule QtRhi
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    \brief Describes a texture-to-texture copy operation.
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    An empty pixelSize() indicates that the entire subresource is to be copied.
    A default constructed copy description therefore leads to copying the
    entire subresource at level 0 of layer 0.
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    \note The source texture must be created with
    QRhiTexture::UsedAsTransferSource.
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    \note The source and destination rectangles defined by pixelSize(),
    sourceTopLeft(), and destinationTopLeft() must fit the source and
    destination textures, respectively. The behavior is undefined otherwise.
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 */

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/*!
    Constructs an empty texture copy description.
 */
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QRhiTextureCopyDescription::QRhiTextureCopyDescription()
{
}

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/*!
    \class QRhiReadbackDescription
    \inmodule QtRhi
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    \brief Describes a readback (reading back texture contents from possibly GPU-only memory) operation.
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    The source of the readback operation is either a QRhiTexture or the
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    current backbuffer of the currently targeted QRhiSwapChain. When
    texture() is not set, the swapchain is used. Otherwise the specified
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    QRhiTexture is treated as the source.

    \note Textures used in readbacks must be created with
    QRhiTexture::UsedAsTransferSource.

    \note Swapchains used in readbacks must be created with
    QRhiSwapChain::UsedAsTransferSource.

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    layer() and level() are only applicable when the source is a QRhiTexture.
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    \note Multisample textures cannot be read back. Readbacks are supported for
    multisample swapchain buffers however.
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 */

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/*!
    Constructs an empty texture readback description.

    \note The source texture is set to null by default, which is still a valid
    readback: it specifies that the backbuffer of the current swapchain is to
    be read back. (current meaning the frame's target swapchain at the time of
    committing the QRhiResourceUpdateBatch with the
    \l{QRhiResourceUpdateBatch::readBackTexture()}{texture readback} on it)
 */
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QRhiReadbackDescription::QRhiReadbackDescription()
{
}

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/*!
    Constructs an texture readback description that specifies that level 0 of
    layer 0 of \a texture is to be read back.

    \note \a texture can also be null in which case this constructor is
    identical to the argumentless variant.
 */
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QRhiReadbackDescription::QRhiReadbackDescription(QRhiTexture *texture)
    : m_texture(texture)
{
}

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/*!
    \class QRhiReadbackResult
    \inmodule QtRhi
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    \brief Describes the results of a potentially asynchronous readback operation.
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    When \l completed is set, the function is invoked when the \l data is
    available. \l format and \l pixelSize are set upon completion together with
    \l data.
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 */

/*!
    \class QRhiNativeHandles
    \inmodule QtRhi
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    \brief Base class for classes exposing backend-specific collections of native resource objects.
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 */

/*!
    \class QRhiResource
    \inmodule QtRhi
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    \brief Base class for classes encapsulating native resource objects.
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 */

/*!
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    \internal
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 */
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QRhiResource::QRhiResource(QRhiImplementation *rhi_)
    : rhi(rhi_)
{
}
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/*!
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   Destructor.
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 */
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QRhiResource::~QRhiResource()
{
}
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/*!
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    \fn void QRhiResource::release()
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    Releases the underlying native graphics resources. Safe to call multiple
    times, subsequent invocations will be a no-op then.

    Once release() is called, the QRhiResource instance can be reused, by
    calling the appropriate \c build() function again, or destroyed.
 */

/*!
    Releases native graphics resources, if there is any, and destroys the
    QRhiResource. Equivalent to \c{r->release(); delete r; }.
 */
void QRhiResource::releaseAndDestroy()
{
    release();
    delete this;
}

/*!
    \return the currently set object name. By default the name is empty.
 */
QByteArray QRhiResource::name() const
{
    return objectName;
}

/*!
    Sets a \a name for the object.

    This has two uses: to get descriptive names for the native graphics
    resources visible in graphics debugging tools, such as
    \l{https://renderdoc.org/}{RenderDoc} and
    \l{https://developer.apple.com/xcode/}{XCode}, and in the output stream of
    QRhiProfiler.

    When it comes to naming native objects by relaying the name via the
    appropriate graphics API, note that the name is ignored when
    QRhi::DebugMarkers are not supported, and may, depending on the backend,
    also be ignored when QRhi::EnableDebugMarkers is not set.

    \note The name may be ignored for objects other than buffers,
    renderbuffers, and textures, depending on the backend.

    \note The name may be modified. For slotted resources, such as a QRhiBuffer
    backed by multiple native buffers, QRhi will append a suffix to make the
    underlying native buffers easily distinguishable from each other.
 */
void QRhiResource::setName(const QByteArray &name)
{
    objectName = name;
    objectName.replace(',', '_'); // cannot contain comma for QRhiProfiler
}

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/*!
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    \return true if this resource is shareable between QRhi instances via a
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    QRhiResourceSharingHost. It also means that such an QRhiResource can
    outlive the QRhi on which it was created.

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    \note Once a shareable QRhiResource is \c orphaned, meaning that the QRhi
    from which it was created gets destroyed, \c{build()} is not a valid
    operation anymore. The QRhiResource can then only be used in graphics
    operations (as the underlying graphics objects are still there and valid)
    or can be released, as long as the QRhiResourceSharingHost,
    with which the creator QRhi was associated with, has at least one
    associated QRhi alive.

    \note Shareable resources typically include buffers, textures, samplers,
    and renderbuffers. Most backends will not support other type of shareable
    resources.
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    \sa QRhiResourceSharingHost
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 */
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bool QRhiResource::isShareable() const
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{
    return false;
}

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/*!
    \class QRhiBuffer
    \inmodule QtRhi
    \brief Vertex, index, or uniform (constant) buffer resource.
 */

/*!
    \enum QRhiBuffer::Type
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    Specifies storage type of buffer resource.
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    \value Immutable Indicates that the data is not expected to change ever
    after the initial upload. Under the hood such buffer resources are
    typically placed in device local (GPU) memory (on systems where
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    applicable). Uploading new data is possible, but may be expensive. The
    upload typically happens by copying to a separate, host visible staging
    buffer from which a GPU buffer-to-buffer copy is issued into the actual
    GPU-only buffer.
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    \value Static Indicates that the data is expected to change only
    infrequently. Typically placed in device local (GPU) memory, where
    applicable. On backends where host visible staging buffers are used for
    uploading, the staging buffers are kept around for this type, unlike with
    Immutable, so subsequent uploads do not suffer in performance. Frequent
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    updates, especially updates in consecutive frames, should be avoided.
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    \value Dynamic Indicates that the data is expected to change frequently.
    Not recommended for large buffers. Typically backed by host visible memory
    in 2 copies in order to allow for changing without stalling the graphics
    pipeline. The double buffering is managed transparently to the applications
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    and is not exposed in the API here in any form. This is the recommended,
    and, with some backends, the only possible, type for buffers with
    UniformBuffer usage.
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 */

/*!
    \enum QRhiBuffer::UsageFlag
    Flag values to specify how the buffer is going to be used.

    \value VertexBuffer Vertex buffer
    \value IndexBuffer Index buffer
    \value UniformBuffer Uniform (constant) buffer
 */

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/*!
    \fn void QRhiBuffer::setSize(int sz)

    Sets the size of the buffer in bytes. The size is normally specified in
    QRhi::newBuffer() so this function is only used when the size has to be
    changed. As with other setters, the size only takes effect when calling
    build(), and for already built buffers this involves releasing the previous
    native resource and creating new ones under the hood.

    Backends may choose to allocate buffers bigger than \a sz in order to
    fulfill alignment requirements. This is hidden from the applications and
    size() will always report the size requested in \a sz.
 */

/*!
    \internal
 */
QRhiBuffer::QRhiBuffer(QRhiImplementation *rhi, Type type_, UsageFlags usage_, int size_)
    : QRhiResource(rhi),
      m_type(type_), m_usage(usage_), m_size(size_)
{
}

/*!
    \fn bool QRhiBuffer::build()

    Creates the corresponding native graphics resources. If there are already
    resources present due to an earlier build() with no corresponding
    release(), then release() is called implicitly first.

    \return \c true when successful, \c false when a graphics operation failed.
    Regardless of the return value, calling release() is always safe.
 */

/*!
    \class QRhiRenderBuffer
    \inmodule QtRhi
    \brief Renderbuffer resource.

    Renderbuffers cannot be sampled or read but have some benefits over
    textures in some cases:

    A DepthStencil renderbuffer may be lazily allocated and be backed by
    transient memory with some APIs. On some platforms this may mean the
    depth/stencil buffer uses no physical backing at all.

    Color renderbuffers are useful since QRhi::MultisampleRenderBuffer may be
    supported even when QRhi::MultisampleTexture is not.

    How the renderbuffer is implemented by a backend is not exposed to the
    applications. In some cases it may be backed by ordinary textures, while in
    others there may be a different kind of native resource used.
 */

/*!
    \enum QRhiRenderBuffer::Type
    Specifies the type of the renderbuffer

    \value DepthStencil Combined depth/stencil
    \value Color Color
 */

/*!
    \enum QRhiRenderBuffer::Flag
    Flag values for flags() and setFlags()

    \value UsedWithSwapChainOnly For DepthStencil renderbuffers this indicates
    that the renderbuffer is only used in combination with a QRhiSwapChain and
    never in other ways. Relevant with some backends, while others ignore it.
    With OpenGL where a separate windowing system interface API is in use (EGL,
    GLX, etc.), the flag is important since it avoids creating any actual
    resource as there is already a windowing system provided depth/stencil
    buffer as requested by QSurfaceFormat.
 */

/*!
    \internal
 */
QRhiRenderBuffer::QRhiRenderBuffer(QRhiImplementation *rhi, Type type_, const QSize &pixelSize_,
                                   int sampleCount_, Flags flags_)
    : QRhiResource(rhi),
      m_type(type_), m_pixelSize(pixelSize_), m_sampleCount(sampleCount_), m_flags(flags_)
{
}

/*!
    \fn bool QRhiRenderBuffer::build()

    Creates the corresponding native graphics resources. If there are already
    resources present due to an earlier build() with no corresponding
    release(), then release() is called implicitly first.

    \return \c true when successful, \c false when a graphics operation failed.
    Regardless of the return value, calling release() is always safe.
 */

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/*!
    \class QRhiTexture
    \inmodule QtRhi
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    \brief Texture resource.
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 */

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/*!
    \enum QRhiTexture::Flag

    Flag values to specify how the texture is going to be used. Not honoring
    the flags set before build() and attempting to use the texture in ways that
    was not declared upfront can lead to unspecified behavior or decreased
    performance depending on the backend and the underlying graphics API.

    \value RenderTarget The texture going to be used in combination with
    QRhiTextureRenderTarget

    \value ChangesFrequently Performance hint to indicate that the texture
    contents will change frequently and so staging buffers, if any, are to be
    kept alive to avoid performance hits

    \value CubeMap The texture is a cubemap. Such textures have 6 layers, one
    for each face in the order of +X, -X, +Y, -Y, +Z, -Z. Cubemap textures
    cannot be multisample.

     \value MipMapped The texture has mipmaps. The appropriate mip count is
     calculated automatically and can also be retrieved via
     QRhi::mipLevelsForSize(). The images for the mip levels have to be
     provided in the texture uploaded or generated via
     QRhiResourceUpdateBatch::generateMips(). Multisample textures cannot have
     mipmaps.

    \value sRGB Use an sRGB format

    \value UsedAsTransferSource The texture is used as the source of a texture
    copy or readback, meaning the texture is given as the source in
    QRhiResourceUpdateBatch::copyTexture() or
    QRhiResourceUpdateBatch::readBackTexture().

     \value UsedWithGenerateMips The texture is going to be used with
     QRhiResourceUpdateBatch::generateMips().
 */

/*!
    \enum QRhiTexture::Format

    Specifies the texture format. See also QRhi::isTextureFormatSupported() and
    note that flags() can modify the format when QRhiTexture::sRGB is set.

    \value UnknownFormat Not a valid format. This cannot be passed to setFormat().
    \value RGBA8
    \value BGRA8
    \value R8
    \value R16
    \value D16
    \value D32
    \value BC1
    \value BC2
    \value BC3
    \value BC4
    \value BC5
    \value BC6H
    \value BC7
    \value ETC2_RGB8
    \value ETC2_RGB8A1
    \value ETC2_RGBA8
    \value ASTC_4x4
    \value ASTC_5x4
    \value ASTC_5x5
    \value ASTC_6x5
    \value ASTC_6x6
    \value ASTC_8x5
    \value ASTC_8x6
    \value ASTC_8x8
    \value ASTC_10x5
    \value ASTC_10x6
    \value ASTC_10x8
    \value ASTC_10x10
    \value ASTC_12x10
    \value ASTC_12x12
 */

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/*!
    \internal
 */
QRhiTexture::QRhiTexture(QRhiImplementation *rhi, Format format_, const QSize &pixelSize_,
                         int sampleCount_, Flags flags_)
    : QRhiResource(rhi),
      m_format(format_), m_pixelSize(pixelSize_), m_sampleCount(sampleCount_), m_flags(flags_)
{
}

/*!
    \fn bool QRhiTexture::build()

    Creates the corresponding native graphics resources. If there are already
    resources present due to an earlier build() with no corresponding
    release(), then release() is called implicitly first.

    \return \c true when successful, \c false when a graphics operation failed.
    Regardless of the return value, calling release() is always safe.
 */

/*!
    \return a pointer to a backend-specific QRhiNativeHandles subclass, such as
    QRhiVulkanTextureNativeHandles. The returned value is null when exposing
    the underlying native resources is not supported by the backend.

    \sa QRhiVulkanTextureNativeHandles, QRhiD3D11TextureNativeHandles,
    QRhiMetalTextureNativeHandles, QRhiGles2TextureNativeHandles
 */
const QRhiNativeHandles *QRhiTexture::nativeHandles()
{
    return nullptr;
}

/*!
    Similar to build() except that no new native textures are created. Instead,
    the texture from \a src is used.

    This allows importing an existing native texture object (which must belong
    to the same device or sharing context, depending on the graphics API) from
    an external graphics engine.

    \note format(), pixelSize(), sampleCount(), and flags() must still be set
    correctly. Passing incorrect sizes and other values to QRhi::newTexture()
    and then following it with a buildFrom() expecting that the native texture
    object alone is sufficient to deduce such values is \b wrong and will lead
    to problems.

    \note QRhiTexture does not take ownership of the texture object. release()
    does not free the object or any associated memory.

    The opposite of this operation, exposing a QRhiTexture-created native
    texture object to a foreign engine, is possible via nativeHandles().

    \sa QRhiVulkanTextureNativeHandles, QRhiD3D11TextureNativeHandles,
    QRhiMetalTextureNativeHandles, QRhiGles2TextureNativeHandles
 */
bool QRhiTexture::buildFrom(const QRhiNativeHandles *src)
{
    Q_UNUSED(src);
    return false;
}

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/*!
    \class QRhiSampler
    \inmodule QtRhi
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