shadowmap example skeleton

Shaders and camera logic not yet there.

It is essential to have a test that exercises depth-only passes and
rendering into a depth texture that is then used in another pass. Some
simple shadow casting directional light is a good example for this.

examples/rhi/rhi.pro

@@ -14,7 +14,8 @@ SUBDIRS += \
     triquadcube \
     offscreen \
     floattexture \
-    mrt
+    mrt \
+    shadowmap
 
 qtConfig(vulkan) {
     SUBDIRS += \

examples/rhi/shadowmap/buildshaders.bat

+qsb --glsl 120 --hlsl 50 --msl 12 -c shadowmap.vert -o shadowmap.vert.qsb
+qsb --glsl 120 --hlsl 50 --msl 12 -c shadowmap.frag -o shadowmap.frag.qsb
+qsb --glsl 120 --hlsl 50 --msl 12 -c light.vert -o light.vert.qsb
+qsb --glsl 120 --hlsl 50 --msl 12 -c light.frag -o light.frag.qsb

examples/rhi/shadowmap/light.frag

+#version 440
+
+layout(location = 0) in vec3 vECVertNormal;
+layout(location = 1) in vec3 vECVertPos;
+
+layout(location = 0) out vec4 fragColor;
+
+void main()
+{
+    vec3 ECCameraPosition = vec3(0.0, 0.0, 4.0); // matches C++
+    vec3 ka = vec3(0.05, 0.05, 0.05);
+    vec3 kd = vec3(0.3, 0.7, 0.6);
+    vec3 ks = vec3(0.66, 0.66, 0.66);
+    vec3 ECLightPosition = vec3(0.0, 10.0, 1.0); // matches C++
+    vec3 attenuation = vec3(1.0, 0.0, 0.0);
+    vec3 color = vec3(1.0, 1.0, 1.0);
+    float intensity = 0.8;
+    float specularExp = 150.0;
+
+    vec3 unnormL = ECLightPosition - vECVertPos;
+    float dist = length(unnormL);
+    float att = 1.0 / (attenuation.x + attenuation.y * dist + attenuation.z * dist * dist);
+
+    vec3 N = normalize(vECVertNormal);
+    vec3 L = normalize(unnormL);
+    float NL = max(0.0, dot(N, L));
+    vec3 dColor = att * intensity * color * NL;
+
+    vec3 R = reflect(-L, N);
+    vec3 V = normalize(ECCameraPosition - vECVertPos);
+    float RV = max(0.0, dot(R, V));
+    vec3 sColor = att * intensity * color * pow(RV, specularExp);
+
+    fragColor = vec4(ka + kd * dColor + ks * sColor, 1.0);
+}

examples/rhi/shadowmap/light.vert

+#version 440
+
+layout(location = 0) in vec4 position;
+layout(location = 1) in vec3 normal;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+    mat4 mv;
+    mat4 m;
+    mat3 n;
+} ubuf;
+
+out gl_PerVertex { vec4 gl_Position; };
+
+layout(location = 0) out vec3 vECVertNormal;
+layout(location = 1) out vec3 vECVertPos;
+
+void main()
+{
+    vECVertNormal = normalize(ubuf.n * normal);
+    vECVertPos = vec3(ubuf.m * position);
+    gl_Position = ubuf.mvp * position;
+}

examples/rhi/shadowmap/shadowmap.cpp

+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "../shared/examplefw.h"
+#include "../shared/cube_with_normals.h"
+
+// Depth texture / shadow sampler / shadow map example.
+// Not available on GLES 2.0.
+
+static float quadVertexData[] =
+{ // Y up, CCW, x-y-z, normalX-normalY-normalZ
+  -0.5f,   0.5f, 0.0f,  0.0f, 0.0f, 1.0f,
+  -0.5f,  -0.5f, 0.0f,  0.0f, 0.0f, 1.0f,
+  0.5f,   -0.5f, 0.0f,  0.0f, 0.0f, 1.0f,
+  0.5f,   0.5f,  0.0f,  0.0f, 0.0f, 1.0f
+};
+
+static quint16 quadIndexData[] =
+{
+    0, 1, 2, 0, 2, 3
+};
+
+struct {
+    QVector<QRhiResource *> releasePool;
+    QRhiBuffer *vbuf = nullptr;
+    QRhiBuffer *ibuf = nullptr;
+    QRhiBuffer *ubuf = nullptr;
+    QRhiShaderResourceBindings *srb = nullptr;
+    QRhiGraphicsPipeline *ps = nullptr;
+    QRhiResourceUpdateBatch *initialUpdates = nullptr;
+    QMatrix4x4 winProj;
+    float cubeRot = 0;
+
+    QRhiTextureRenderTarget *rt = nullptr;
+    QRhiRenderPassDescriptor *rtRp = nullptr;
+    QRhiTexture *shadowMap = nullptr;
+    QRhiGraphicsPipeline *shadowPs = nullptr;
+} d;
+
+const int UBLOCK_SIZE = 64 + 64 + 64 + 48;
+const int UBUF_SLOTS = 4; // 2 objects * 2 passes with different cameras
+
+void Window::customInit()
+{
+    if (!m_r->isTextureFormatSupported(QRhiTexture::D32F))
+        qFatal("Depth texture is not supported");
+
+    d.vbuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(quadVertexData) + sizeof(cube));
+    d.vbuf->build();
+    d.releasePool << d.vbuf;
+
+    d.ibuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::IndexBuffer, sizeof(quadIndexData));
+    d.ibuf->build();
+    d.releasePool << d.ibuf;
+
+    const int oneRoundedUniformBlockSize = m_r->ubufAligned(UBLOCK_SIZE);
+    d.ubuf = m_r->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, UBUF_SLOTS * oneRoundedUniformBlockSize);
+    d.ubuf->build();
+    d.releasePool << d.ubuf;
+
+    d.srb = m_r->newShaderResourceBindings();
+    d.releasePool << d.srb;
+    const QRhiShaderResourceBinding::StageFlags stages = QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage;
+    d.srb->setBindings({ QRhiShaderResourceBinding::uniformBufferWithDynamicOffset(0, stages, d.ubuf, 64) });
+    d.srb->build();
+
+    d.ps = m_r->newGraphicsPipeline();
+    d.releasePool << d.ps;
+    d.ps->setShaderStages({
+        { QRhiGraphicsShaderStage::Vertex, getShader(QLatin1String(":/light.vert.qsb")) },
+        { QRhiGraphicsShaderStage::Fragment, getShader(QLatin1String(":/light.frag.qsb")) }
+    });
+    d.ps->setDepthTest(true);
+    d.ps->setDepthWrite(true);
+    // fits both the quad and cube vertex data
+    QRhiVertexInputLayout inputLayout;
+    inputLayout.setBindings({
+        { 6 * sizeof(float) }
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float3, 0 },
+        { 0, 1, QRhiVertexInputAttribute::Float3, 3 * sizeof(float) }
+    });
+    d.ps->setVertexInputLayout(inputLayout);
+    d.ps->setShaderResourceBindings(d.srb);
+    d.ps->setRenderPassDescriptor(m_rp);
+    d.ps->build();
+
+    d.initialUpdates = m_r->nextResourceUpdateBatch();
+    d.initialUpdates->uploadStaticBuffer(d.vbuf, 0, sizeof(quadVertexData), quadVertexData);
+    d.initialUpdates->uploadStaticBuffer(d.vbuf, sizeof(quadVertexData), sizeof(cube), cube);
+    d.initialUpdates->uploadStaticBuffer(d.ibuf, quadIndexData);
+
+    d.shadowMap = m_r->newTexture(QRhiTexture::D32F, QSize(512, 512), 1, QRhiTexture::RenderTarget);
+    d.releasePool << d.shadowMap;
+    d.shadowMap->build();
+
+    QRhiTextureRenderTargetDescription rtDesc;
+    rtDesc.setDepthTexture(d.shadowMap);
+    d.rt = m_r->newTextureRenderTarget(rtDesc);
+    d.releasePool << d.rt;
+    d.rtRp = d.rt->newCompatibleRenderPassDescriptor();
+    d.releasePool << d.rtRp;
+    d.rt->setRenderPassDescriptor(d.rtRp);
+    d.rt->build();
+
+    d.shadowPs = m_r->newGraphicsPipeline();
+    d.releasePool << d.shadowPs;
+    d.shadowPs->setShaderStages({
+        { QRhiGraphicsShaderStage::Vertex, getShader(QLatin1String(":/shadowmap.vert.qsb")) },
+        { QRhiGraphicsShaderStage::Fragment, getShader(QLatin1String(":/shadowmap.frag.qsb")) }
+    });
+    d.shadowPs->setDepthTest(true);
+    d.shadowPs->setDepthWrite(true);
+    inputLayout.setBindings({
+        { 6 * sizeof(float) }
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float3, 0 }
+    });
+    d.shadowPs->setVertexInputLayout(inputLayout);
+    d.shadowPs->setShaderResourceBindings(d.srb);
+    d.shadowPs->setRenderPassDescriptor(d.rtRp);
+    d.shadowPs->build();
+}
+
+void Window::customRelease()
+{
+    for (QRhiResource *r : d.releasePool)
+        r->releaseAndDestroy();
+    d.releasePool.clear();
+}
+
+static void enqueueScene(QRhiCommandBuffer *cb, int oneRoundedUniformBlockSize, int firstUbufSlot)
+{
+    // draw the ground (the quad)
+    cb->setShaderResources(d.srb, { { 0, quint32(firstUbufSlot * oneRoundedUniformBlockSize) } });
+    cb->setVertexInput(0, { { d.vbuf, 0 } }, d.ibuf, 0, QRhiCommandBuffer::IndexUInt16);
+    cb->drawIndexed(6);
+
+    // Draw the object (the cube). Both vertex and uniform data are in the same
+    // buffer, right after the quad's.
+    cb->setShaderResources(d.srb, { qMakePair(0, quint32((firstUbufSlot + 1) * oneRoundedUniformBlockSize)) });
+    cb->setVertexInput(0, { { d.vbuf, sizeof(quadVertexData) } });
+    cb->draw(36);
+}
+
+void Window::customRender()
+{
+    const QSize outputSizeInPixels = m_sc->currentPixelSize();
+    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
+    QRhiResourceUpdateBatch *u = m_r->nextResourceUpdateBatch();
+    if (d.initialUpdates) {
+        u->merge(d.initialUpdates);
+        d.initialUpdates->release();
+        d.initialUpdates = nullptr;
+    }
+
+    const QVector3D lightPos(0, 10, 1); // must match the shader
+    const QVector3D shadowCamCenter(0, 0, 0);
+    const QVector3D shadowCamUp(0, 1, 0);
+
+    const int oneRoundedUniformBlockSize = m_r->ubufAligned(UBLOCK_SIZE);
+
+    // uniform data for the ground
+    if (d.winProj != m_proj) {
+        d.winProj = m_proj;
+
+        QMatrix4x4 m;
+        m.scale(4.0f);
+        m.rotate(-60, 1, 0, 0);
+
+        QMatrix4x4 mv;
+        mv.translate(0, 0, -4); // must match the shader
+        mv *= m;
+
+        // for the main pass
+        QMatrix4x4 mvp = m_r->clipSpaceCorrMatrix() * m_rawProj * mv;
+        u->updateDynamicBuffer(d.ubuf, 0, 64, mvp.constData());
+        mv = m_r->clipSpaceCorrMatrix() * mv;
+        u->updateDynamicBuffer(d.ubuf, 64, 64, mv.constData());
+        m = m_r->clipSpaceCorrMatrix() * m;
+        u->updateDynamicBuffer(d.ubuf, 128, 64, m.constData());
+        QMatrix3x3 n = m.normalMatrix();
+        u->updateDynamicBuffer(d.ubuf, 192, 48, n.constData());
+
+        // for the shadow pass
+        mvp = m_r->clipSpaceCorrMatrix();
+        mvp.perspective(45.0f, 1, 0.01f, 1000.0f);
+        mvp.lookAt(lightPos, shadowCamCenter, shadowCamUp);
+        mvp *= mv;
+        u->updateDynamicBuffer(d.ubuf, 2 * oneRoundedUniformBlockSize, 64, mvp.constData());
+    }
+
+    // uniform data for the rotating cube
+    QMatrix4x4 m;
+    m.translate(0, 1, 0);
+    m.scale(0.5f);
+    m.rotate(d.cubeRot, 1, 0, 0);
+    m.rotate(20, 0, 1, 0);
+    d.cubeRot += 1;
+
+    QMatrix4x4 mv;
+    mv.translate(0, 0, -4); // must match the shader
+    mv *= m;
+
+    // for the main pass
+    QMatrix4x4 mvp = m_r->clipSpaceCorrMatrix() * m_rawProj * mv;
+    u->updateDynamicBuffer(d.ubuf, oneRoundedUniformBlockSize, 64, mvp.constData());
+    mv = m_r->clipSpaceCorrMatrix() * mv;
+    u->updateDynamicBuffer(d.ubuf, oneRoundedUniformBlockSize + 64, 64, mv.constData());
+    m = m_r->clipSpaceCorrMatrix() * m;
+    u->updateDynamicBuffer(d.ubuf, oneRoundedUniformBlockSize + 128, 64, m.constData());
+    QMatrix3x3 n = m.normalMatrix();
+    u->updateDynamicBuffer(d.ubuf, oneRoundedUniformBlockSize + 192, 48, n.constData());
+
+    // for the shadow pass
+    mvp = m_r->clipSpaceCorrMatrix();
+    mvp.perspective(45.0f, 1, 0.01f, 1000.0f);
+    mvp.lookAt(lightPos, shadowCamCenter, shadowCamUp);
+    mvp *= mv;
+    u->updateDynamicBuffer(d.ubuf, 3 * oneRoundedUniformBlockSize, 64, mvp.constData());
+
+    cb->resourceUpdate(u);
+
+    // shadow pass
+    const QSize shadowMapSize = d.shadowMap->pixelSize();
+    cb->beginPass(d.rt, QRhiColorClearValue(), { 1.0f, 0 });
+    cb->setGraphicsPipeline(d.shadowPs);
+    cb->setViewport({ 0, 0, float(shadowMapSize.width()), float(shadowMapSize.height()) });
+    enqueueScene(cb, oneRoundedUniformBlockSize, 2);
+    cb->endPass();
+
+    // main pass
+    cb->beginPass(m_sc->currentFrameRenderTarget(), { 0.4f, 0.7f, 0.0f, 1.0f }, { 1.0f, 0 });
+    cb->setGraphicsPipeline(d.ps);
+    cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
+    enqueueScene(cb, oneRoundedUniformBlockSize, 0);
+    cb->endPass();
+}

examples/rhi/shadowmap/shadowmap.frag

+#version 440
+
+void main()
+{
+}

examples/rhi/shadowmap/shadowmap.pro

+TEMPLATE = app
+
+QT += rhi
+
+SOURCES = \
+    shadowmap.cpp
+
+RESOURCES = shadowmap.qrc
+
+target.path = $$[QT_INSTALL_EXAMPLES]/rhi/shadowmap
+INSTALLS += target

examples/rhi/shadowmap/shadowmap.qrc

+<!DOCTYPE RCC><RCC version="1.0">
+  <qresource>
+    <file>shadowmap.vert.qsb</file>
+    <file>shadowmap.frag.qsb</file>
+    <file>light.vert.qsb</file>
+    <file>light.frag.qsb</file>
+</qresource>
+</RCC>

examples/rhi/shadowmap/shadowmap.vert

+#version 440
+
+layout(location = 0) in vec4 position;
+
+layout(std140, binding = 0) uniform buf {
+    mat4 mvp;
+} ubuf;
+
+out gl_PerVertex { vec4 gl_Position; };
+
+void main()
+{
+    gl_Position = ubuf.mvp * position;
+}

examples/rhi/shared/cube_with_normals.h

+#ifndef CUBENORM_H
+#define CUBENORM_H
+
+// clang-format off
+static const float cube[] = {
+    -1.0f,-1.0f,-1.0f,   -1, 0, 0,  // -X side
+    -1.0f,-1.0f, 1.0f,   -1, 0, 0,
+    -1.0f, 1.0f, 1.0f,   -1, 0, 0,
+    -1.0f, 1.0f, 1.0f,   -1, 0, 0,
+    -1.0f, 1.0f,-1.0f,   -1, 0, 0,
+    -1.0f,-1.0f,-1.0f,   -1, 0, 0,
+
+    -1.0f,-1.0f,-1.0f,    0, 0, -1, // -Z side
+     1.0f, 1.0f,-1.0f,    0, 0, -1,
+     1.0f,-1.0f,-1.0f,    0, 0, -1,
+    -1.0f,-1.0f,-1.0f,    0, 0, -1,
+    -1.0f, 1.0f,-1.0f,    0, 0, -1,
+     1.0f, 1.0f,-1.0f,    0, 0, -1,
+
+    -1.0f,-1.0f,-1.0f,    0, -1, 0, // -Y side
+     1.0f,-1.0f,-1.0f,    0, -1, 0,
+     1.0f,-1.0f, 1.0f,    0, -1, 0,
+    -1.0f,-1.0f,-1.0f,    0, -1, 0,
+     1.0f,-1.0f, 1.0f,    0, -1, 0,
+    -1.0f,-1.0f, 1.0f,    0, -1, 0,
+
+    -1.0f, 1.0f,-1.0f,    0, 1, 0, // +Y side
+    -1.0f, 1.0f, 1.0f,    0, 1, 0,
+     1.0f, 1.0f, 1.0f,    0, 1, 0,
+    -1.0f, 1.0f,-1.0f,    0, 1, 0,
+     1.0f, 1.0f, 1.0f,    0, 1, 0,
+     1.0f, 1.0f,-1.0f,    0, 1, 0,
+
+     1.0f, 1.0f,-1.0f,    1, 0, 0, // +X side
+     1.0f, 1.0f, 1.0f,    1, 0, 0,
+     1.0f,-1.0f, 1.0f,    1, 0, 0,
+     1.0f,-1.0f, 1.0f,    1, 0, 0,
+     1.0f,-1.0f,-1.0f,    1, 0, 0,
+     1.0f, 1.0f,-1.0f,    1, 0, 0,
+
+    -1.0f, 1.0f, 1.0f,    0, 0, 1, // +Z side
+    -1.0f,-1.0f, 1.0f,    0, 0, 1,
+     1.0f, 1.0f, 1.0f,    0, 0, 1,
+    -1.0f,-1.0f, 1.0f,    0, 0, 1,
+     1.0f,-1.0f, 1.0f,    0, 0, 1,
+     1.0f, 1.0f, 1.0f,    0, 0, 1
+};
+// clang-format on
+
+#endif

examples/rhi/shared/examplefw.h

@@ -157,6 +157,7 @@ protected:
     QRhiRenderPassDescriptor *m_rp = nullptr;
 
     QMatrix4x4 m_proj;
+    QMatrix4x4 m_rawProj;
 
     QElapsedTimer m_timer;
     int m_frameCount;
@@ -337,8 +338,9 @@ void Window::resizeSwapChain()
     m_frameCount = 0;
     m_timer.restart();
 
-    m_proj = m_r->clipSpaceCorrMatrix();
-    m_proj.perspective(45.0f, outputSize.width() / (float) outputSize.height(), 0.01f, 1000.0f);
+    m_rawProj.setToIdentity();
+    m_rawProj.perspective(45.0f, outputSize.width() / (float) outputSize.height(), 0.01f, 1000.0f);
+    m_proj = m_r->clipSpaceCorrMatrix() * m_rawProj;
     m_proj.translate(0, 0, -4);
 }
 

src/rhi/qrhi.cpp

@@ -2782,6 +2782,28 @@ QRhiGraphicsPipeline::QRhiGraphicsPipeline(QRhiImplementation *rhi)
     Regardless of the return value, calling release() is always safe.
  */
 
+/*!
+    \fn void QRhiGraphicsPipeline::setDepthTest(bool enable)
+
+    Enables or disables depth testing. Both depth test and the writing out of
+    depth data are disabled by default.
+
+    \sa setDepthWrite()
+ */
+
+/*!
+    \fn void QRhiGraphicsPipeline::setDepthWrite(bool enable)
+
+    Controls the writing out of depth data into the depth buffer. By default
+    this is disabled. Depth write is typically enabled together with the depth
+    test.
+
+    \note Enabling depth write without having depth testing enabled may not
+    lead to the desired result, and should be avoided.
+
+    \sa setDepthTest()
+ */
+
 /*!
     \class QRhiSwapChain
     \inmodule QtRhi