Add a null backend

examples/rhi/shared/examplefw.h

@@ -62,6 +62,8 @@
 #include <QFile>
 #include <QRhiProfiler>
 
+#include <QRhiNullInitParams>
+
 #ifndef QT_NO_OPENGL
 #include <QRhiGles2InitParams>
 #include <QOpenGLContext>
@@ -92,6 +94,7 @@ QBakedShader getShader(const QString &name)
 
 enum GraphicsApi
 {
+    Null,
     OpenGL,
     Vulkan,
     D3D11,
@@ -103,6 +106,8 @@ GraphicsApi graphicsApi;
 QString graphicsApiName()
 {
     switch (graphicsApi) {
+    case Null:
+        return QLatin1String("Null (no output)");
     case OpenGL:
         return QLatin1String("OpenGL 2.x");
     case Vulkan:
@@ -235,6 +240,11 @@ bool Window::event(QEvent *e)
 
 void Window::init()
 {
+    if (graphicsApi == Null) {
+        QRhiNullInitParams params;
+        m_r = QRhi::create(QRhi::Null, &params, rhiFlags);
+    }
+
 #ifndef QT_NO_OPENGL
     if (graphicsApi == OpenGL) {
         m_context = new QOpenGLContext;
@@ -446,6 +456,8 @@ int main(int argc, char **argv)
     // Allow overriding via the command line.
     QCommandLineParser cmdLineParser;
     cmdLineParser.addHelpOption();
+    QCommandLineOption nullOption({ "n", "null" }, QLatin1String("Null"));
+    cmdLineParser.addOption(nullOption);
     QCommandLineOption glOption({ "g", "opengl" }, QLatin1String("OpenGL (2.x)"));
     cmdLineParser.addOption(glOption);
     QCommandLineOption vkOption({ "v", "vulkan" }, QLatin1String("Vulkan"));
@@ -455,6 +467,8 @@ int main(int argc, char **argv)
     QCommandLineOption mtlOption({ "m", "metal" }, QLatin1String("Metal"));
     cmdLineParser.addOption(mtlOption);
     cmdLineParser.process(app);
+    if (cmdLineParser.isSet(nullOption))
+        graphicsApi = Null;
     if (cmdLineParser.isSet(glOption))
         graphicsApi = OpenGL;
     if (cmdLineParser.isSet(vkOption))

src/rhi/qrhi.cpp

@@ -37,6 +37,7 @@
 #include "qrhi_p.h"
 #include <qmath.h>
 
+#include "qrhinull_p.h"
 #ifndef QT_NO_OPENGL
 #include "qrhigles2_p.h"
 #endif
@@ -586,6 +587,9 @@ QRhi *QRhi::create(Implementation impl, QRhiInitParams *params, Flags flags)
     QScopedPointer<QRhi> r(new QRhi);
 
     switch (impl) {
+    case Null:
+        r->d = new QRhiNull(params);
+        break;
     case Vulkan:
 #if QT_CONFIG(vulkan)
         r->d = new QRhiVulkan(params);

src/rhi/qrhi.h

@@ -1109,6 +1109,7 @@ class Q_RHI_EXPORT QRhi
 {
 public:
     enum Implementation {
+        Null,
         Vulkan,
         OpenGLES2,
         D3D11,

src/rhi/qrhinull.h

+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt RHI module
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QRHINULL_H
+#define QRHINULL_H
+
+#include <QtRhi/qrhi.h>
+
+QT_BEGIN_NAMESPACE
+
+struct Q_RHI_EXPORT QRhiNullInitParams : public QRhiInitParams
+{
+};
+
+struct Q_RHI_EXPORT QRhiNullNativeHandles : public QRhiNativeHandles
+{
+};
+
+struct Q_RHI_EXPORT QRhiNullTextureNativeHandles : public QRhiNativeHandles
+{
+    uint texture = 0;
+};
+
+QT_END_NAMESPACE
+
+#endif

src/rhi/qrhinull_p.h

+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt RHI module
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QRHINULL_P_H
+#define QRHINULL_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qrhinull.h"
+#include "qrhi_p.h"
+
+QT_BEGIN_NAMESPACE
+
+struct QNullBuffer : public QRhiBuffer
+{
+    QNullBuffer(QRhiImplementation *rhi, Type type, UsageFlags usage, int size);
+    void release() override;
+    bool build() override;
+};
+
+struct QNullRenderBuffer : public QRhiRenderBuffer
+{
+    QNullRenderBuffer(QRhiImplementation *rhi, Type type, const QSize &pixelSize,
+                       int sampleCount, QRhiRenderBuffer::Flags flags);
+    void release() override;
+    bool build() override;
+    QRhiTexture::Format backingFormat() const override;
+};
+
+struct QNullTexture : public QRhiTexture
+{
+    QNullTexture(QRhiImplementation *rhi, Format format, const QSize &pixelSize,
+                  int sampleCount, Flags flags);
+    void release() override;
+    bool build() override;
+    bool buildFrom(const QRhiNativeHandles *src) override;
+    const QRhiNativeHandles *nativeHandles() override;
+
+    QRhiNullTextureNativeHandles nativeHandlesStruct;
+};
+
+struct QNullSampler : public QRhiSampler
+{
+    QNullSampler(QRhiImplementation *rhi, Filter magFilter, Filter minFilter, Filter mipmapMode,
+                  AddressMode u, AddressMode v, AddressMode w);
+    void release() override;
+    bool build() override;
+};
+
+struct QNullRenderPassDescriptor : public QRhiRenderPassDescriptor
+{
+    QNullRenderPassDescriptor(QRhiImplementation *rhi);
+    void release() override;
+};
+
+struct QNullBasicRenderTargetData
+{
+    QNullBasicRenderTargetData(QRhiImplementation *) { }
+
+    QNullRenderPassDescriptor *rp = nullptr;
+    QSize pixelSize;
+    float dpr = 1;
+};
+
+struct QNullReferenceRenderTarget : public QRhiReferenceRenderTarget
+{
+    QNullReferenceRenderTarget(QRhiImplementation *rhi);
+    void release() override;
+    Type type() const override;
+    QSize sizeInPixels() const override;
+    float devicePixelRatio() const override;
+
+    QNullBasicRenderTargetData d;
+};
+
+struct QNullTextureRenderTarget : public QRhiTextureRenderTarget
+{
+    QNullTextureRenderTarget(QRhiImplementation *rhi, const QRhiTextureRenderTargetDescription &desc, Flags flags);
+    void release() override;
+
+    Type type() const override;
+    QSize sizeInPixels() const override;
+    float devicePixelRatio() const override;
+
+    QRhiRenderPassDescriptor *newCompatibleRenderPassDescriptor() override;
+    bool build() override;
+
+    QNullBasicRenderTargetData d;
+};
+
+struct QNullShaderResourceBindings : public QRhiShaderResourceBindings
+{
+    QNullShaderResourceBindings(QRhiImplementation *rhi);
+    void release() override;
+    bool build() override;
+};
+
+struct QNullGraphicsPipeline : public QRhiGraphicsPipeline
+{
+    QNullGraphicsPipeline(QRhiImplementation *rhi);
+    void release() override;
+    bool build() override;
+};
+
+struct QNullCommandBuffer : public QRhiCommandBuffer
+{
+    QNullCommandBuffer(QRhiImplementation *rhi);
+    void release() override;
+};
+
+struct QNullSwapChain : public QRhiSwapChain
+{
+    QNullSwapChain(QRhiImplementation *rhi);
+    void release() override;
+
+    QRhiCommandBuffer *currentFrameCommandBuffer() override;
+    QRhiRenderTarget *currentFrameRenderTarget() override;
+
+    QSize surfacePixelSize() override;
+
+    QRhiRenderPassDescriptor *newCompatibleRenderPassDescriptor() override;
+    bool buildOrResize() override;
+
+    QNullReferenceRenderTarget rt;
+    QNullCommandBuffer cb;
+    int frameCount = 0;
+};
+
+class QRhiNull : public QRhiImplementation
+{
+public:
+    QRhiNull(QRhiInitParams *params);
+
+    bool create(QRhi::Flags flags) override;
+    void destroy() override;
+
+    QRhiGraphicsPipeline *createGraphicsPipeline() override;
+    QRhiShaderResourceBindings *createShaderResourceBindings() override;
+    QRhiBuffer *createBuffer(QRhiBuffer::Type type,
+                             QRhiBuffer::UsageFlags usage,
+                             int size) override;
+    QRhiRenderBuffer *createRenderBuffer(QRhiRenderBuffer::Type type,
+                                         const QSize &pixelSize,
+                                         int sampleCount,
+                                         QRhiRenderBuffer::Flags flags) override;
+    QRhiTexture *createTexture(QRhiTexture::Format format,
+                               const QSize &pixelSize,
+                               int sampleCount,
+                               QRhiTexture::Flags flags) override;
+    QRhiSampler *createSampler(QRhiSampler::Filter magFilter, QRhiSampler::Filter minFilter,
+                               QRhiSampler::Filter mipmapMode,
+                               QRhiSampler:: AddressMode u, QRhiSampler::AddressMode v, QRhiSampler::AddressMode w) override;
+
+    QRhiTextureRenderTarget *createTextureRenderTarget(const QRhiTextureRenderTargetDescription &desc,
+                                                       QRhiTextureRenderTarget::Flags flags) override;
+
+    QRhiSwapChain *createSwapChain() override;
+    QRhi::FrameOpResult beginFrame(QRhiSwapChain *swapChain) override;
+    QRhi::FrameOpResult endFrame(QRhiSwapChain *swapChain) override;
+    QRhi::FrameOpResult beginOffscreenFrame(QRhiCommandBuffer **cb) override;
+    QRhi::FrameOpResult endOffscreenFrame() override;
+    QRhi::FrameOpResult finish() override;
+
+    void resourceUpdate(QRhiCommandBuffer *cb, QRhiResourceUpdateBatch *resourceUpdates) override;
+
+    void beginPass(QRhiCommandBuffer *cb,
+                   QRhiRenderTarget *rt,
+                   const QRhiColorClearValue &colorClearValue,
+                   const QRhiDepthStencilClearValue &depthStencilClearValue,
+                   QRhiResourceUpdateBatch *resourceUpdates) override;
+    void endPass(QRhiCommandBuffer *cb, QRhiResourceUpdateBatch *resourceUpdates) override;
+
+    void setGraphicsPipeline(QRhiCommandBuffer *cb,
+                             QRhiGraphicsPipeline *ps,
+                             QRhiShaderResourceBindings *srb) override;
+
+    void setVertexInput(QRhiCommandBuffer *cb,
+                        int startBinding, const QVector<QRhiCommandBuffer::VertexInput> &bindings,
+                        QRhiBuffer *indexBuf, quint32 indexOffset,
+                        QRhiCommandBuffer::IndexFormat indexFormat) override;
+
+    void setViewport(QRhiCommandBuffer *cb, const QRhiViewport &viewport) override;
+    void setScissor(QRhiCommandBuffer *cb, const QRhiScissor &scissor) override;
+    void setBlendConstants(QRhiCommandBuffer *cb, const QVector4D &c) override;
+    void setStencilRef(QRhiCommandBuffer *cb, quint32 refValue) override;
+
+    void draw(QRhiCommandBuffer *cb, quint32 vertexCount,
+              quint32 instanceCount, quint32 firstVertex, quint32 firstInstance) override;
+
+    void drawIndexed(QRhiCommandBuffer *cb, quint32 indexCount,
+                     quint32 instanceCount, quint32 firstIndex,
+                     qint32 vertexOffset, quint32 firstInstance) override;
+
+    void debugMarkBegin(QRhiCommandBuffer *cb, const QByteArray &name) override;
+    void debugMarkEnd(QRhiCommandBuffer *cb) override;
+    void debugMarkMsg(QRhiCommandBuffer *cb, const QByteArray &msg) override;
+
+    QVector<int> supportedSampleCounts() const override;
+    int ubufAlignment() const override;
+    bool isYUpInFramebuffer() const override;
+    QMatrix4x4 clipSpaceCorrMatrix() const override;
+    bool isTextureFormatSupported(QRhiTexture::Format format, QRhiTexture::Flags flags) const override;
+    bool isFeatureSupported(QRhi::Feature feature) const override;
+    int resourceSizeLimit(QRhi::ResourceSizeLimit limit) const override;
+    const QRhiNativeHandles *nativeHandles() override;
+
+    QRhiNullNativeHandles nativeHandlesStruct;
+};
+
+QT_END_NAMESPACE
+
+#endif

src/rhi/rhi.pro

@@ -10,11 +10,14 @@ HEADERS += \
     qrhi.h \
     qrhi_p.h \
     qrhiprofiler.h \
-    qrhiprofiler_p.h
+    qrhiprofiler_p.h \
+    qrhinull.h \
+    qrhinull_p.h
 
 SOURCES += \
     qrhi.cpp \
-    qrhiprofiler.cpp
+    qrhiprofiler.cpp \
+    qrhinull.cpp
 
 qtConfig(opengl) {
     HEADERS += \