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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
// This is a compact, minimal demo of deciding the backend at runtime while
// using the exact same shaders and rendering code without any branching
// whatsoever once the QWindow is up and the RHI is initialized.
#include <QGuiApplication>
#include <QCommandLineParser>
#include "examplewindow.h"
QString graphicsApiName(QRhi::Implementation graphicsApi);
QRhi::Implementation graphicsApiFromCmd(const QGuiApplication &app);
int main(int argc, char **argv)
{
QGuiApplication app(argc, argv);
QRhi::Implementation graphicsApi = graphicsApiFromCmd(app);
QSurfaceFormat fmt;
fmt.setDepthBufferSize(24);
fmt.setStencilBufferSize(8);
QSurfaceFormat::setDefaultFormat(fmt);
ExampleWindow w(graphicsApi);
#if QT_CONFIG(vulkan)
QVulkanInstance inst;
if (graphicsApi == QRhi::Vulkan) {
inst.setLayers({ "VK_LAYER_KHRONOS_validation" });
inst.setExtensions(QRhiVulkanInitParams::preferredInstanceExtensions());
if (!inst.create()) {
qWarning("Failed to create Vulkan instance, switching to OpenGL");
graphicsApi = QRhi::OpenGLES2;
}
}
#endif
#if QT_CONFIG(vulkan)
if (graphicsApi == QRhi::Vulkan)
w.setVulkanInstance(&inst);
#endif
w.resize(1280, 720);
w.setTitle(QCoreApplication::applicationName() + QLatin1String(" - ") + graphicsApiName(graphicsApi));
w.show();
int ret = app.exec();
// Window::event() will not get invoked when the
// PlatformSurfaceAboutToBeDestroyed event is sent during the QWindow
// destruction. That happens only when exiting via app::quit() instead of
// the more common QWindow::close(). Take care of it: if the QPlatformWindow
// is still around (there was no close() yet), get rid of the swapchain
// while it's not too late.
if (w.handle())
w.releaseSwapChain();
return ret;
}
QString graphicsApiName(QRhi::Implementation graphicsApi)
{
switch (graphicsApi) {
case QRhi::Null:
return QLatin1String("Null (no output)");
case QRhi::OpenGLES2:
return QLatin1String("OpenGL 2.x");
case QRhi::Vulkan:
return QLatin1String("Vulkan");
case QRhi::D3D11:
return QLatin1String("Direct3D 11");
case QRhi::D3D12:
return QLatin1String("Direct3D 12");
case QRhi::Metal:
return QLatin1String("Metal");
default:
break;
}
return QString();
}
QRhi::Implementation graphicsApiFromCmd(const QGuiApplication &app) {
QRhi::Implementation graphicsApi;
#if defined(Q_OS_WIN)
graphicsApi = QRhi::D3D11;
#elif QT_CONFIG(metal)
graphicsApi = QRhi::Metal;
#elif QT_CONFIG(vulkan)
graphicsApi = QRhi::Vulkan;
#else
graphicsApi = QRhi::OpenGLES2;
#endif
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"));
cmdLineParser.addOption(vkOption);
QCommandLineOption d3d11Option({ "d", "d3d11" }, QLatin1String("Direct3D 11"));
cmdLineParser.addOption(d3d11Option);
QCommandLineOption d3d12Option({ "D", "d3d12" }, QLatin1String("Direct3D 12"));
cmdLineParser.addOption(d3d12Option);
QCommandLineOption mtlOption({ "m", "metal" }, QLatin1String("Metal"));
cmdLineParser.addOption(mtlOption);
cmdLineParser.process(app);
if (cmdLineParser.isSet(nullOption))
graphicsApi = QRhi::Null;
if (cmdLineParser.isSet(glOption))
graphicsApi = QRhi::OpenGLES2;
if (cmdLineParser.isSet(vkOption))
graphicsApi = QRhi::Vulkan;
if (cmdLineParser.isSet(d3d11Option))
graphicsApi = QRhi::D3D11;
if (cmdLineParser.isSet(d3d12Option))
graphicsApi = QRhi::D3D12;
if (cmdLineParser.isSet(mtlOption))
graphicsApi = QRhi::Metal;
qDebug("Selected graphics API is %s", qPrintable(graphicsApiName(graphicsApi)));
qDebug("This is a multi-api example, use command line arguments to override:\n%s", qPrintable(cmdLineParser.helpText()));
return graphicsApi;
}
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