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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include "rhisquircle.h"
#include <QtQuick/QQuickWindow>
#include <QtCore/QFile>
#include <QtCore/QRunnable>
#include <rhi/qrhi.h>
class SquircleRenderer : public QObject
{
Q_OBJECT
public:
void setT(qreal t) { m_t = t; }
void setWindow(QQuickWindow *window) { m_window = window; }
public slots:
void frameStart();
void mainPassRecordingStart();
private:
qreal m_t = 0;
QQuickWindow *m_window;
QShader m_vertexShader;
QShader m_fragmentShader;
std::unique_ptr<QRhiBuffer> m_vertexBuffer;
std::unique_ptr<QRhiBuffer> m_uniformBuffer;
std::unique_ptr<QRhiShaderResourceBindings> m_srb;
std::unique_ptr<QRhiGraphicsPipeline> m_pipeline;
};
//! [init]
RhiSquircle::RhiSquircle()
{
connect(this, &QQuickItem::windowChanged, this, &RhiSquircle::handleWindowChanged);
}
void RhiSquircle::handleWindowChanged(QQuickWindow *win)
{
if (win) {
connect(win, &QQuickWindow::beforeSynchronizing, this, &RhiSquircle::sync, Qt::DirectConnection);
connect(win, &QQuickWindow::sceneGraphInvalidated, this, &RhiSquircle::cleanup, Qt::DirectConnection);
// Ensure we start with cleared to black. The squircle's blend mode relies on this.
win->setColor(Qt::black);
}
}
//! [init]
// The safe way to release custom graphics resources is to both connect to
// sceneGraphInvalidated() and implement releaseResources(). To support
// threaded render loops the latter performs the SquircleRenderer destruction
// via scheduleRenderJob(). Note that the RhiSquircle may be gone by the time
// the QRunnable is invoked.
void RhiSquircle::cleanup()
{
// This function is invoked on the render thread, if there is one.
delete m_renderer;
m_renderer = nullptr;
}
class CleanupJob : public QRunnable
{
public:
CleanupJob(SquircleRenderer *renderer) : m_renderer(renderer) { }
void run() override { delete m_renderer; }
private:
SquircleRenderer *m_renderer;
};
void RhiSquircle::releaseResources()
{
window()->scheduleRenderJob(new CleanupJob(m_renderer), QQuickWindow::BeforeSynchronizingStage);
m_renderer = nullptr;
}
void RhiSquircle::setT(qreal t)
{
if (t == m_t)
return;
m_t = t;
emit tChanged();
if (window())
window()->update();
}
//! [sync]
void RhiSquircle::sync()
{
// This function is invoked on the render thread, if there is one.
if (!m_renderer) {
m_renderer = new SquircleRenderer;
// Initializing resources is done before starting to record the
// renderpass, regardless of wanting an underlay or overlay.
connect(window(), &QQuickWindow::beforeRendering, m_renderer, &SquircleRenderer::frameStart, Qt::DirectConnection);
// Here we want an underlay and therefore connect to
// beforeRenderPassRecording. Changing to afterRenderPassRecording
// would render the squircle on top (overlay).
connect(window(), &QQuickWindow::beforeRenderPassRecording, m_renderer, &SquircleRenderer::mainPassRecordingStart, Qt::DirectConnection);
}
m_renderer->setT(m_t);
m_renderer->setWindow(window());
}
//! [sync]
static QShader getShader(const QString &name)
{
QFile f(name);
if (f.open(QIODevice::ReadOnly))
return QShader::fromSerialized(f.readAll());
return QShader();
}
static const float vertices[] = {
-1, -1,
1, -1,
-1, 1,
1, 1
};
//! [frame-start]
void SquircleRenderer::frameStart()
{
// This function is invoked on the render thread, if there is one.
QRhi *rhi = m_window->rhi();
if (!rhi) {
qWarning("QQuickWindow is not using QRhi for rendering");
return;
}
QRhiSwapChain *swapChain = m_window->swapChain();
if (!swapChain) {
qWarning("No QRhiSwapChain?");
return;
}
QRhiResourceUpdateBatch *resourceUpdates = rhi->nextResourceUpdateBatch();
if (!m_pipeline) {
m_vertexShader = getShader(QLatin1String(":/scenegraph/rhiunderqml/squircle_rhi.vert.qsb"));
if (!m_vertexShader.isValid())
qWarning("Failed to load vertex shader; rendering will be incorrect");
m_fragmentShader = getShader(QLatin1String(":/scenegraph/rhiunderqml/squircle_rhi.frag.qsb"));
if (!m_fragmentShader.isValid())
qWarning("Failed to load fragment shader; rendering will be incorrect");
m_vertexBuffer.reset(rhi->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, sizeof(vertices)));
m_vertexBuffer->create();
resourceUpdates->uploadStaticBuffer(m_vertexBuffer.get(), vertices);
const quint32 UBUF_SIZE = 4 + 4; // 2 floats
m_uniformBuffer.reset(rhi->newBuffer(QRhiBuffer::Dynamic, QRhiBuffer::UniformBuffer, UBUF_SIZE));
m_uniformBuffer->create();
float yDir = rhi->isYUpInNDC() ? 1.0f : -1.0f;
resourceUpdates->updateDynamicBuffer(m_uniformBuffer.get(), 4, 4, &yDir);
m_srb.reset(rhi->newShaderResourceBindings());
const auto visibleToAll = QRhiShaderResourceBinding::VertexStage | QRhiShaderResourceBinding::FragmentStage;
m_srb->setBindings({
QRhiShaderResourceBinding::uniformBuffer(0, visibleToAll, m_uniformBuffer.get())
});
m_srb->create();
QRhiVertexInputLayout inputLayout;
inputLayout.setBindings({
{ 2 * sizeof(float) }
});
inputLayout.setAttributes({
{ 0, 0, QRhiVertexInputAttribute::Float2, 0 }
});
m_pipeline.reset(rhi->newGraphicsPipeline());
m_pipeline->setTopology(QRhiGraphicsPipeline::TriangleStrip);
QRhiGraphicsPipeline::TargetBlend blend;
blend.enable = true;
blend.srcColor = QRhiGraphicsPipeline::SrcAlpha;
blend.srcAlpha = QRhiGraphicsPipeline::SrcAlpha;
blend.dstColor = QRhiGraphicsPipeline::One;
blend.dstAlpha = QRhiGraphicsPipeline::One;
m_pipeline->setTargetBlends({ blend });
m_pipeline->setShaderStages({
{ QRhiShaderStage::Vertex, m_vertexShader },
{ QRhiShaderStage::Fragment, m_fragmentShader }
});
m_pipeline->setVertexInputLayout(inputLayout);
m_pipeline->setShaderResourceBindings(m_srb.get());
m_pipeline->setRenderPassDescriptor(swapChain->currentFrameRenderTarget()->renderPassDescriptor());
m_pipeline->create();
}
float t = m_t;
resourceUpdates->updateDynamicBuffer(m_uniformBuffer.get(), 0, 4, &t);
swapChain->currentFrameCommandBuffer()->resourceUpdate(resourceUpdates);
}
//! [frame-start]
//! [frame-render]
void SquircleRenderer::mainPassRecordingStart()
{
// This function is invoked on the render thread, if there is one.
QRhi *rhi = m_window->rhi();
QRhiSwapChain *swapChain = m_window->swapChain();
if (!rhi || !swapChain)
return;
const QSize outputPixelSize = swapChain->currentFrameRenderTarget()->pixelSize();
QRhiCommandBuffer *cb = m_window->swapChain()->currentFrameCommandBuffer();
cb->setViewport({ 0.0f, 0.0f, float(outputPixelSize.width()), float(outputPixelSize.height()) });
cb->setGraphicsPipeline(m_pipeline.get());
cb->setShaderResources();
const QRhiCommandBuffer::VertexInput vbufBinding(m_vertexBuffer.get(), 0);
cb->setVertexInput(0, 1, &vbufBinding);
cb->draw(4);
}
//! [frame-render]
#include "rhisquircle.moc"
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