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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
//! [0]
#include <QGuiApplication>
#include <QImage>
#include <QFile>
#include <rhi/qrhi.h>
int main(int argc, char **argv)
{
QGuiApplication app(argc, argv);
#if QT_CONFIG(vulkan)
QVulkanInstance inst;
#endif
std::unique_ptr<QRhi> rhi;
#if defined(Q_OS_WIN)
QRhiD3D12InitParams params;
rhi.reset(QRhi::create(QRhi::D3D12, ¶ms));
#elif QT_CONFIG(metal)
QRhiMetalInitParams params;
rhi.reset(QRhi::create(QRhi::Metal, ¶ms));
#elif QT_CONFIG(vulkan)
inst.setExtensions(QRhiVulkanInitParams::preferredInstanceExtensions());
if (inst.create()) {
QRhiVulkanInitParams params;
params.inst = &inst;
rhi.reset(QRhi::create(QRhi::Vulkan, ¶ms));
} else {
qFatal("Failed to create Vulkan instance");
}
#endif
if (rhi)
qDebug() << rhi->backendName() << rhi->driverInfo();
else
qFatal("Failed to initialize RHI");
float rotation = 0.0f;
float opacity = 1.0f;
int opacityDir = 1;
std::unique_ptr<QRhiTexture> tex(rhi->newTexture(QRhiTexture::RGBA8,
QSize(1280, 720),
1,
QRhiTexture::RenderTarget | QRhiTexture::UsedAsTransferSource));
tex->create();
std::unique_ptr<QRhiTextureRenderTarget> rt(rhi->newTextureRenderTarget({ tex.get() }));
std::unique_ptr<QRhiRenderPassDescriptor> rp(rt->newCompatibleRenderPassDescriptor());
rt->setRenderPassDescriptor(rp.get());
rt->create();
QMatrix4x4 viewProjection = rhi->clipSpaceCorrMatrix();
viewProjection.perspective(45.0f, 1280 / 720.f, 0.01f, 1000.0f);
viewProjection.translate(0, 0, -4);
static float vertexData[] = { // 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,
};
std::unique_ptr<QRhiBuffer> vbuf(rhi->newBuffer(QRhiBuffer::Immutable,
QRhiBuffer::VertexBuffer,
sizeof(vertexData)));
vbuf->create();
std::unique_ptr<QRhiBuffer> ubuf(rhi->newBuffer(QRhiBuffer::Dynamic,
QRhiBuffer::UniformBuffer,
64 + 4));
ubuf->create();
std::unique_ptr<QRhiShaderResourceBindings> srb(rhi->newShaderResourceBindings());
srb->setBindings({
QRhiShaderResourceBinding::uniformBuffer(0,
QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage,
ubuf.get())
});
srb->create();
std::unique_ptr<QRhiGraphicsPipeline> ps(rhi->newGraphicsPipeline());
QRhiGraphicsPipeline::TargetBlend premulAlphaBlend;
premulAlphaBlend.enable = true;
ps->setTargetBlends({ premulAlphaBlend });
static auto getShader = [](const QString &name) {
QFile f(name);
return f.open(QIODevice::ReadOnly) ? QShader::fromSerialized(f.readAll()) : QShader();
};
ps->setShaderStages({
{ QRhiShaderStage::Vertex, getShader(QLatin1String("color.vert.qsb")) },
{ QRhiShaderStage::Fragment, getShader(QLatin1String("color.frag.qsb")) }
});
QRhiVertexInputLayout inputLayout;
inputLayout.setBindings({
{ 5 * sizeof(float) }
});
inputLayout.setAttributes({
{ 0, 0, QRhiVertexInputAttribute::Float2, 0 },
{ 0, 1, QRhiVertexInputAttribute::Float3, 2 * sizeof(float) }
});
ps->setVertexInputLayout(inputLayout);
ps->setShaderResourceBindings(srb.get());
ps->setRenderPassDescriptor(rp.get());
ps->create();
QRhiCommandBuffer *cb;
for (int frame = 0; frame < 20; ++frame) {
rhi->beginOffscreenFrame(&cb);
QRhiResourceUpdateBatch *u = rhi->nextResourceUpdateBatch();
if (frame == 0)
u->uploadStaticBuffer(vbuf.get(), vertexData);
QMatrix4x4 mvp = viewProjection;
mvp.rotate(rotation, 0, 1, 0);
u->updateDynamicBuffer(ubuf.get(), 0, 64, mvp.constData());
rotation += 5.0f;
u->updateDynamicBuffer(ubuf.get(), 64, 4, &opacity);
opacity += opacityDir * 0.2f;
if (opacity < 0.0f || opacity > 1.0f) {
opacityDir *= -1;
opacity = qBound(0.0f, opacity, 1.0f);
}
cb->beginPass(rt.get(), Qt::green, { 1.0f, 0 }, u);
cb->setGraphicsPipeline(ps.get());
cb->setViewport({ 0, 0, 1280, 720 });
cb->setShaderResources();
const QRhiCommandBuffer::VertexInput vbufBinding(vbuf.get(), 0);
cb->setVertexInput(0, 1, &vbufBinding);
cb->draw(3);
QRhiReadbackResult readbackResult;
u = rhi->nextResourceUpdateBatch();
u->readBackTexture({ tex.get() }, &readbackResult);
cb->endPass(u);
rhi->endOffscreenFrame();
QImage image(reinterpret_cast<const uchar *>(readbackResult.data.constData()),
readbackResult.pixelSize.width(),
readbackResult.pixelSize.height(),
QImage::Format_RGBA8888_Premultiplied);
if (rhi->isYUpInFramebuffer())
image = image.mirrored();
image.save(QString::asprintf("frame%d.png", frame));
}
return 0;
}
//! [0]
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