1 files changed, 305 insertions, 0 deletions
diff --git a/tests/manual/rhi/multiview/multiview.cpp b/tests/manual/rhi/multiview/multiview.cpp
new file mode 100644
index 0000000000..a89821eb8e
--- /dev/null
+++ b/tests/manual/rhi/multiview/multiview.cpp
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+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include "../shared/examplefw.h"
+
+// Multiview rendering. Renders the same geometry (a triangle) with two
+// different transforms into two layers of a texture array object in a *single*
+// draw call. (NB under the hood it is at the hardware/driver's discretion what
+// happens; it may very well map to some simple looping and still drawing
+// twice, whereas with modern hardware it can be expected to be implemented
+// more efficiently, but that's hidden from us)
+
+// Toggle this to exercise 4x MSAA for the texture array that is the render
+// target of the multiview render pass. The elements written by the multiview
+// render pass get resolved to a non-multisample texture array at the end of
+// the pass.
+static bool MSAA = false;
+
+static float quadVertexData[] =
+{ // Y up, CCW
+  -0.5f,   0.5f,   0.0f, 0.0f,
+  -0.5f,  -0.5f,   0.0f, 1.0f,
+  0.5f,   -0.5f,   1.0f, 1.0f,
+  0.5f,   0.5f,    1.0f, 0.0f
+};
+
+static quint16 quadIndexData[] =
+{
+    0, 1, 2, 0, 2, 3
+};
+
+static float triangleData[] =
+{ // Y up, CCW
+     0.0f,   0.5f,   1.0f, 0.0f, 0.0f,
+    -0.5f,  -0.5f,   0.0f, 1.0f, 0.0f,
+     0.5f,  -0.5f,   0.0f, 0.0f, 1.0f
+};
+
+static const int INSTANCE_COUNT = 5;
+
+static float instanceData[INSTANCE_COUNT * 3] =
+{
+    0.4f,  0.0f, 0.0f,
+    0.2f,  0.0f, 0.1f,
+    0.0f,  0.0f, 0.2f,
+    -0.2f, 0.0f, 0.3f,
+    -0.4f, 0.0f, 0.4f
+};
+
+struct {
+    QList<QRhiResource *> releasePool;
+    QRhiBuffer *vbuf = nullptr;
+    QRhiBuffer *instanceBuf = nullptr;
+    QRhiBuffer *ibuf = nullptr;
+    QRhiBuffer *ubuf = nullptr;
+    QRhiTextureRenderTarget *rt = nullptr;
+    QRhiRenderPassDescriptor *rtRp = nullptr;
+    QRhiSampler *sampler = nullptr;
+    QRhiGraphicsPipeline *ps = nullptr;
+    QRhiResourceUpdateBatch *initialUpdates = nullptr;
+    QMatrix4x4 winProj;
+    QRhiTexture *tex = nullptr;
+    QRhiTexture *resolveTex = nullptr; // only if MSAA is true
+    QRhiTexture *ds = nullptr;
+    QRhiShaderResourceBindings *srb[2] = {};
+
+    QRhiBuffer *triUbuf = nullptr;
+    QRhiShaderResourceBindings *triSrb = nullptr;
+    QRhiGraphicsPipeline *triPs = nullptr;
+    QMatrix4x4 triBaseMvp;
+} d;
+
+void Window::customInit()
+{
+    if (!m_r->isFeatureSupported(QRhi::MultiView))
+        qFatal("Multiview is not supported");
+
+    int sampleCount = 1;
+    if (MSAA) {
+        qDebug("Using 4x MSAA for the multiview render pass");
+        sampleCount = 4;
+    }
+
+    // texture array with 2 elements, e.g. 0 is left eye, 1 is right
+    d.tex = m_r->newTextureArray(QRhiTexture::RGBA8, 2, QSize(512, 512), sampleCount, QRhiTexture::RenderTarget);
+    d.releasePool << d.tex;
+    d.tex->create();
+
+    if (MSAA) {
+        d.resolveTex = m_r->newTextureArray(QRhiTexture::RGBA8, 2, QSize(512, 512), 1, QRhiTexture::RenderTarget);
+        d.releasePool << d.resolveTex;
+        d.resolveTex->create();
+    }
+
+    // Have a depth-stencil buffer, just to exercise it, the triangles will be
+    // rendered with depth test/write enabled. The catch here is that we must
+    // use a texture array for depth/stencil as well, so QRhiRenderBuffer is
+    // not an option anymore.
+    d.ds = m_r->newTextureArray(QRhiTexture::D24S8, 2, QSize(512, 512), sampleCount, QRhiTexture::RenderTarget);
+    d.releasePool << d.ds;
+    d.ds->create();
+
+    // set up the multiview render target
+    QRhiColorAttachment multiViewAtt(d.tex);
+    // using array elements 0 and 1
+    multiViewAtt.setLayer(0);
+    multiViewAtt.setMultiViewCount(2); // the view count must be set both on the render target and the pipeline
+
+    // On-screen we work with a non-MSAA texture array, so the fragment shader
+    // does not need to deal with sampler2DMSArray, but can use sampler2DArray
+    // regardless of using multisampling or not. This means using an extra
+    // non-MSAA 2D texture array into which both array elements get resolved at
+    // the end of the multiview render pass.
+    QRhiTexture *textureForOnscreenView = d.tex;
+    if (MSAA) {
+        multiViewAtt.setResolveTexture(d.resolveTex);
+        textureForOnscreenView = d.resolveTex;
+    }
+
+    QRhiTextureRenderTargetDescription rtDesc(multiViewAtt);
+    rtDesc.setDepthTexture(d.ds);
+
+    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->create();
+
+    // vertex buffer used by both passes
+    d.vbuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(quadVertexData) + sizeof(triangleData));
+    d.vbuf->create();
+    d.releasePool << d.vbuf;
+
+    // data for the instanced translation attribute
+    d.instanceBuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(instanceData));
+    d.instanceBuf->create();
+    d.releasePool << d.instanceBuf;
+
+    // resources for the on-screen visualizer
+    d.ibuf = m_r->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::IndexBuffer, sizeof(quadIndexData));
+    d.ibuf->create();
+    d.releasePool << d.ibuf;
+
+    const int oneRoundedUniformBlockSize = m_r->ubufAligned(72);
+    d.ubuf = m_r->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, oneRoundedUniformBlockSize * 2);
+    d.ubuf->create();
+    d.releasePool << d.ubuf;
+
+    d.sampler = m_r->newSampler(QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
+                                QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge);
+    d.releasePool << d.sampler;
+    d.sampler->create();
+
+    // two srbs, just for the quad positioning on-screen
+    for (int i = 0; i < 2; ++i) {
+        QRhiShaderResourceBindings *srb = m_r->newShaderResourceBindings();
+        d.releasePool << srb;
+        srb->setBindings({
+            QRhiShaderResourceBinding::uniformBuffer(0, QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage,
+                                                     d.ubuf, i * oneRoundedUniformBlockSize, 72),
+            QRhiShaderResourceBinding::sampledTexture(1, QRhiShaderResourceBinding::FragmentStage,
+                                                      textureForOnscreenView, d.sampler)
+        });
+        srb->create();
+        d.srb[i] = srb;
+    }
+
+    d.ps = m_r->newGraphicsPipeline();
+    d.releasePool << d.ps;
+    d.ps->setShaderStages({
+        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/texture.vert.qsb")) },
+        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/texture.frag.qsb")) }
+    });
+    QRhiVertexInputLayout inputLayout;
+    inputLayout.setBindings({
+        { 4 * sizeof(float) }
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float2, 0 },
+        { 0, 1, QRhiVertexInputAttribute::Float2, quint32(2 * sizeof(float)) }
+    });
+    d.ps->setVertexInputLayout(inputLayout);
+    d.ps->setShaderResourceBindings(d.srb[0]); // all of them are layout-compatible
+    d.ps->setRenderPassDescriptor(m_rp);
+    d.ps->create();
+
+    d.initialUpdates = m_r->nextResourceUpdateBatch();
+    d.initialUpdates->uploadStaticBuffer(d.vbuf, 0, sizeof(quadVertexData), quadVertexData);
+    d.initialUpdates->uploadStaticBuffer(d.vbuf, sizeof(quadVertexData), sizeof(triangleData), triangleData);
+    d.initialUpdates->uploadStaticBuffer(d.instanceBuf, instanceData);
+    d.initialUpdates->uploadStaticBuffer(d.ibuf, quadIndexData);
+
+    qint32 flip = m_r->isYUpInFramebuffer() ? 1 : 0;
+    for (int i = 0; i < 2; ++i) {
+        d.initialUpdates->updateDynamicBuffer(d.ubuf, i * oneRoundedUniformBlockSize + 64, 4, &flip);
+        float layer = i;
+        d.initialUpdates->updateDynamicBuffer(d.ubuf, i * oneRoundedUniformBlockSize + 68, 4, &layer);
+    }
+
+    // create resources for the multiview render pass
+    d.triUbuf = m_r->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, 128); // mat4 mvp[2]
+    d.releasePool << d.triUbuf;
+    d.triUbuf->create();
+
+    d.triSrb = m_r->newShaderResourceBindings();
+    d.releasePool << d.triSrb;
+    d.triSrb->setBindings({
+        QRhiShaderResourceBinding::uniformBuffer(0, QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage, d.triUbuf)
+    });
+    d.triSrb->create();
+
+    d.triPs = m_r->newGraphicsPipeline();
+    d.releasePool << d.triPs;
+    d.triPs->setShaderStages({
+        { QRhiShaderStage::Vertex, getShader(QLatin1String(":/multiview.vert.qsb")) },
+        { QRhiShaderStage::Fragment, getShader(QLatin1String(":/multiview.frag.qsb")) }
+    });
+    d.triPs->setMultiViewCount(2); // the view count must be set both on the render target and the pipeline
+    inputLayout.setBindings({
+        { 5 * sizeof(float) },
+        { 3 * sizeof(float), QRhiVertexInputBinding::PerInstance }
+    });
+    inputLayout.setAttributes({
+        { 0, 0, QRhiVertexInputAttribute::Float2, 0 },
+        { 0, 1, QRhiVertexInputAttribute::Float3, quint32(2 * sizeof(float)) },
+        { 1, 2, QRhiVertexInputAttribute::Float3, 0 }
+    });
+    d.triPs->setDepthTest(true);
+    d.triPs->setDepthWrite(true);
+    d.triPs->setSampleCount(sampleCount);
+    d.triPs->setVertexInputLayout(inputLayout);
+    d.triPs->setShaderResourceBindings(d.triSrb);
+    d.triPs->setRenderPassDescriptor(d.rtRp);
+    d.triPs->create();
+
+    d.triBaseMvp = m_r->clipSpaceCorrMatrix();
+    d.triBaseMvp.perspective(45.0f, d.rt->pixelSize().width() / float(d.rt->pixelSize().height()), 0.01f, 1000.0f);
+    d.triBaseMvp.translate(0, 0, -2);
+}
+
+void Window::customRelease()
+{
+    qDeleteAll(d.releasePool);
+    d.releasePool.clear();
+}
+
+void Window::customRender()
+{
+    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();
+    QRhiResourceUpdateBatch *u = m_r->nextResourceUpdateBatch();
+    if (d.initialUpdates) {
+        u->merge(d.initialUpdates);
+        d.initialUpdates->release();
+        d.initialUpdates = nullptr;
+    }
+
+    QMatrix4x4 triMvp = d.triBaseMvp;
+    // let's say this is the left eye, make the triangle point left for now
+    triMvp.rotate(90, 0, 0, 1);
+    u->updateDynamicBuffer(d.triUbuf, 0, 64, triMvp.constData());
+    triMvp = d.triBaseMvp;
+    // right for the right eye
+    triMvp.rotate(270, 0, 0, 1);
+    u->updateDynamicBuffer(d.triUbuf, 64, 64, triMvp.constData());
+
+    cb->beginPass(d.rt, QColor::fromRgbF(0.5f, 0.2f, 0.0f, 1.0f), { 1.0f, 0 }, u);
+    cb->setGraphicsPipeline(d.triPs);
+    cb->setViewport({ 0, 0, float(d.rt->pixelSize().width()), float(d.rt->pixelSize().height()) });
+    cb->setShaderResources();
+    const QRhiCommandBuffer::VertexInput multiViewPassVbufBindings[] = {
+        { d.vbuf, quint32(sizeof(quadVertexData)) },
+        { d.instanceBuf, 0 }
+    };
+    cb->setVertexInput(0, 2, multiViewPassVbufBindings);
+    cb->draw(3, INSTANCE_COUNT);
+    cb->endPass();
+
+    // "blit" the two texture layers on-screen just to visualize the contents
+    u = m_r->nextResourceUpdateBatch();
+    if (d.winProj != m_proj) {
+        d.winProj = m_proj;
+        const int oneRoundedUniformBlockSize = m_r->ubufAligned(72);
+        for (int i = 0; i < 2; ++i) {
+            QMatrix4x4 mvp = m_proj;
+            mvp.translate(0, 0, 1);
+            if (i == 0)
+                mvp.translate(-1.0f, 0, 0);
+            else
+                mvp.translate(1.0f, 0, 0);
+            u->updateDynamicBuffer(d.ubuf, i * oneRoundedUniformBlockSize, 64, mvp.constData());
+        }
+    }
+    const QSize outputSizeInPixels = m_sc->currentPixelSize();
+    cb->beginPass(m_sc->currentFrameRenderTarget(), m_clearColor, { 1.0f, 0 }, u);
+    cb->setGraphicsPipeline(d.ps);
+    cb->setViewport({ 0, 0, float(outputSizeInPixels.width()), float(outputSizeInPixels.height()) });
+    const QRhiCommandBuffer::VertexInput quadPassVBufBindings[] = { { d.vbuf, 0 } };
+    cb->setVertexInput(0, 1, quadPassVBufBindings, d.ibuf, 0, QRhiCommandBuffer::IndexUInt16);
+    for (int i = 0; i < 2; ++i) {
+        cb->setShaderResources(d.srb[i]);
+        cb->drawIndexed(6);
+    }
+    cb->endPass();
+}