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50
51#include "openglwindow.h"
52
53#include <QGuiApplication>
54#include <QMatrix4x4>
55#include <QOpenGLShaderProgram>
56#include <QScreen>
57#include <QtMath>
58
59
60//! [1]
61class TriangleWindow : public OpenGLWindow
62{
63public:
64 using OpenGLWindow::OpenGLWindow;
65
66 void initialize() override;
67 void render() override;
68
69private:
70 GLint m_posAttr = 0;
71 GLint m_colAttr = 0;
72 GLint m_matrixUniform = 0;
73
74 QOpenGLShaderProgram *m_program = nullptr;
75 int m_frame = 0;
76};
77//! [1]
78
79//! [2]
80int main(int argc, char **argv)
81{
82 QGuiApplication app(argc, argv);
83
84 QSurfaceFormat format;
85 format.setSamples(16);
86
87 TriangleWindow window;
88 window.setFormat(format);
89 window.resize(w: 640, h: 480);
90 window.show();
91
92 window.setAnimating(true);
93
94 return app.exec();
95}
96//! [2]
97
98
99//! [3]
100static const char *vertexShaderSource =
101 "attribute highp vec4 posAttr;\n"
102 "attribute lowp vec4 colAttr;\n"
103 "varying lowp vec4 col;\n"
104 "uniform highp mat4 matrix;\n"
105 "void main() {\n"
106 " col = colAttr;\n"
107 " gl_Position = matrix * posAttr;\n"
108 "}\n";
109
110static const char *fragmentShaderSource =
111 "varying lowp vec4 col;\n"
112 "void main() {\n"
113 " gl_FragColor = col;\n"
114 "}\n";
115//! [3]
116
117//! [4]
118void TriangleWindow::initialize()
119{
120 m_program = new QOpenGLShaderProgram(this);
121 m_program->addShaderFromSourceCode(type: QOpenGLShader::Vertex, source: vertexShaderSource);
122 m_program->addShaderFromSourceCode(type: QOpenGLShader::Fragment, source: fragmentShaderSource);
123 m_program->link();
124 m_posAttr = m_program->attributeLocation(name: "posAttr");
125 Q_ASSERT(m_posAttr != -1);
126 m_colAttr = m_program->attributeLocation(name: "colAttr");
127 Q_ASSERT(m_colAttr != -1);
128 m_matrixUniform = m_program->uniformLocation(name: "matrix");
129 Q_ASSERT(m_matrixUniform != -1);
130}
131//! [4]
132
133//! [5]
134void TriangleWindow::render()
135{
136 const qreal retinaScale = devicePixelRatio();
137 glViewport(x: 0, y: 0, width: width() * retinaScale, height: height() * retinaScale);
138
139 glClear(GL_COLOR_BUFFER_BIT);
140
141 m_program->bind();
142
143 QMatrix4x4 matrix;
144 matrix.perspective(verticalAngle: 60.0f, aspectRatio: 4.0f / 3.0f, nearPlane: 0.1f, farPlane: 100.0f);
145 matrix.translate(x: 0, y: 0, z: -2);
146 matrix.rotate(angle: 100.0f * m_frame / screen()->refreshRate(), x: 0, y: 1, z: 0);
147
148 m_program->setUniformValue(location: m_matrixUniform, value: matrix);
149
150 static const GLfloat vertices[] = {
151 0.0f, 0.707f,
152 -0.5f, -0.5f,
153 0.5f, -0.5f
154 };
155
156 static const GLfloat colors[] = {
157 1.0f, 0.0f, 0.0f,
158 0.0f, 1.0f, 0.0f,
159 0.0f, 0.0f, 1.0f
160 };
161
162 glVertexAttribPointer(indx: m_posAttr, size: 2, GL_FLOAT, GL_FALSE, stride: 0, ptr: vertices);
163 glVertexAttribPointer(indx: m_colAttr, size: 3, GL_FLOAT, GL_FALSE, stride: 0, ptr: colors);
164
165 glEnableVertexAttribArray(index: m_posAttr);
166 glEnableVertexAttribArray(index: m_colAttr);
167
168 glDrawArrays(GL_TRIANGLES, first: 0, count: 3);
169
170 glDisableVertexAttribArray(index: m_colAttr);
171 glDisableVertexAttribArray(index: m_posAttr);
172
173 m_program->release();
174
175 ++m_frame;
176}
177//! [5]
178

source code of qtbase/examples/gui/openglwindow/main.cpp