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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include <QOpenGLWindow>
#include <QScreen>
#include <QPainter>
#include <QPainterPath>
#include <QGuiApplication>
#include <QMatrix4x4>
#include <QStaticText>
#include <QKeyEvent>
#include "background_renderer.h"
static QPainterPath painterPathForTriangle()
{
static const QPointF bottomLeft(-1.0, -1.0);
static const QPointF top(0.0, 1.0);
static const QPointF bottomRight(1.0, -1.0);
QPainterPath path(bottomLeft);
path.lineTo(top);
path.lineTo(bottomRight);
path.closeSubpath();
return path;
}
class OpenGLWindow : public QOpenGLWindow
{
Q_OBJECT
public:
OpenGLWindow();
protected:
void paintGL() override;
void resizeGL(int w, int h) override;
void keyPressEvent(QKeyEvent *e) override;
private:
void setAnimating(bool enabled);
QMatrix4x4 m_window_normalised_matrix;
QMatrix4x4 m_window_painter_matrix;
QMatrix4x4 m_projection;
QMatrix4x4 m_view;
QMatrix4x4 m_model_triangle;
QMatrix4x4 m_model_text;
FragmentToy m_fragment_toy;
QStaticText m_text_layout;
bool m_animate;
};
// Use NoPartialUpdate. This means that all the rendering goes directly to
// the window surface, no additional framebuffer object stands in the
// middle. This is fine since we will clear the entire framebuffer on each
// paint. Under the hood this means that the behavior is equivalent to the
// manual makeCurrent - perform OpenGL calls - swapBuffers loop that is
// typical in pure QWindow-based applications.
OpenGLWindow::OpenGLWindow()
: QOpenGLWindow(QOpenGLWindow::NoPartialUpdate)
, m_fragment_toy("./background.frag")
, m_text_layout("The triangle and this text is rendered with QPainter")
, m_animate(true)
{
setGeometry(300, 300, 500, 500);
m_view.lookAt(QVector3D(3,1,1),
QVector3D(0,0,0),
QVector3D(0,1,0));
setAnimating(m_animate);
}
void OpenGLWindow::paintGL()
{
m_fragment_toy.draw(size());
QPainter p(this);
p.setWorldTransform(m_window_normalised_matrix.toTransform());
QMatrix4x4 mvp = m_projection * m_view * m_model_triangle;
p.setTransform(mvp.toTransform(), true);
p.fillPath(painterPathForTriangle(), QBrush(QGradient(QGradient::NightFade)));
QTransform text_transform = (m_window_painter_matrix * m_view * m_model_text).toTransform();
p.setTransform(text_transform, false);
p.setPen(QPen(Qt::black));
m_text_layout.prepare(text_transform);
qreal x = - (m_text_layout.size().width() / 2);
qreal y = 0;
p.drawStaticText(x, y, m_text_layout);
m_model_triangle.rotate(-1, 0, 1, 0);
m_model_text.rotate(1, 0, 1, 0);
}
void OpenGLWindow::resizeGL(int w, int h)
{
m_window_normalised_matrix.setToIdentity();
m_window_normalised_matrix.translate(w / 2.0, h / 2.0);
m_window_normalised_matrix.scale(w / 2.0, -h / 2.0);
m_window_painter_matrix.setToIdentity();
m_window_painter_matrix.translate(w / 2.0, h / 2.0);
m_text_layout.setTextWidth(std::max(w * 0.2, 80.0));
m_projection.setToIdentity();
m_projection.perspective(45.f, qreal(w) / qreal(h), 0.1f, 100.f);
}
void OpenGLWindow::keyPressEvent(QKeyEvent *e)
{
if (e->key() == Qt::Key_P) { // pause
m_animate = !m_animate;
setAnimating(m_animate);
}
}
void OpenGLWindow::setAnimating(bool enabled)
{
if (enabled) {
// Animate continuously, throttled by the blocking swapBuffers() call the
// QOpenGLWindow internally executes after each paint. Once that is done
// (frameSwapped signal is emitted), we schedule a new update. This
// obviously assumes that the swap interval (see
// QSurfaceFormat::setSwapInterval()) is non-zero.
connect(this, &QOpenGLWindow::frameSwapped,
this, QOverload<>::of(&QPaintDeviceWindow::update));
update();
} else {
disconnect(this, &QOpenGLWindow::frameSwapped,
this, QOverload<>::of(&QPaintDeviceWindow::update));
}
}
int main(int argc, char **argv)
{
QGuiApplication app(argc, argv);
OpenGLWindow window;
QSurfaceFormat fmt;
fmt.setDepthBufferSize(24);
fmt.setStencilBufferSize(8);
window.setFormat(fmt);
window.show();
return app.exec();
}
#include "main.moc"
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