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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include "openglwindow.h"
#include <QGuiApplication>
#include <QMatrix4x4>
#include <QOpenGLShaderProgram>
#include <QScreen>
#include <QtMath>
//! [1]
class TriangleWindow : public OpenGLWindow
{
public:
using OpenGLWindow::OpenGLWindow;
void initialize() override;
void render() override;
private:
GLint m_posAttr = 0;
GLint m_colAttr = 0;
GLint m_matrixUniform = 0;
QOpenGLShaderProgram *m_program = nullptr;
int m_frame = 0;
};
//! [1]
//! [2]
int main(int argc, char **argv)
{
QGuiApplication app(argc, argv);
QSurfaceFormat format;
format.setSamples(16);
TriangleWindow window;
window.setFormat(format);
window.resize(640, 480);
window.show();
window.setAnimating(true);
return app.exec();
}
//! [2]
//! [3]
static const char *vertexShaderSource =
"attribute highp vec4 posAttr;\n"
"attribute lowp vec4 colAttr;\n"
"varying lowp vec4 col;\n"
"uniform highp mat4 matrix;\n"
"void main() {\n"
" col = colAttr;\n"
" gl_Position = matrix * posAttr;\n"
"}\n";
static const char *fragmentShaderSource =
"varying lowp vec4 col;\n"
"void main() {\n"
" gl_FragColor = col;\n"
"}\n";
//! [3]
//! [4]
void TriangleWindow::initialize()
{
m_program = new QOpenGLShaderProgram(this);
m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
m_program->link();
m_posAttr = m_program->attributeLocation("posAttr");
Q_ASSERT(m_posAttr != -1);
m_colAttr = m_program->attributeLocation("colAttr");
Q_ASSERT(m_colAttr != -1);
m_matrixUniform = m_program->uniformLocation("matrix");
Q_ASSERT(m_matrixUniform != -1);
}
//! [4]
//! [5]
void TriangleWindow::render()
{
const qreal retinaScale = devicePixelRatio();
glViewport(0, 0, width() * retinaScale, height() * retinaScale);
glClear(GL_COLOR_BUFFER_BIT);
m_program->bind();
QMatrix4x4 matrix;
matrix.perspective(60.0f, 4.0f / 3.0f, 0.1f, 100.0f);
matrix.translate(0, 0, -2);
matrix.rotate(100.0f * m_frame / screen()->refreshRate(), 0, 1, 0);
m_program->setUniformValue(m_matrixUniform, matrix);
static const GLfloat vertices[] = {
0.0f, 0.707f,
-0.5f, -0.5f,
0.5f, -0.5f
};
static const GLfloat colors[] = {
1.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 1.0f
};
glVertexAttribPointer(m_posAttr, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glVertexAttribPointer(m_colAttr, 3, GL_FLOAT, GL_FALSE, 0, colors);
glEnableVertexAttribArray(m_posAttr);
glEnableVertexAttribArray(m_colAttr);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(m_colAttr);
glDisableVertexAttribArray(m_posAttr);
m_program->release();
++m_frame;
}
//! [5]
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