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50
51#include "mainwidget.h"
52
53#include <QMouseEvent>
54
55#include <cmath>
56
57MainWidget::~MainWidget()
58{
59 // Make sure the context is current when deleting the texture
60 // and the buffers.
61 makeCurrent();
62 delete texture;
63 delete geometries;
64 doneCurrent();
65}
66
67//! [0]
68void MainWidget::mousePressEvent(QMouseEvent *e)
69{
70 // Save mouse press position
71 mousePressPosition = QVector2D(e->localPos());
72}
73
74void MainWidget::mouseReleaseEvent(QMouseEvent *e)
75{
76 // Mouse release position - mouse press position
77 QVector2D diff = QVector2D(e->localPos()) - mousePressPosition;
78
79 // Rotation axis is perpendicular to the mouse position difference
80 // vector
81 QVector3D n = QVector3D(diff.y(), diff.x(), 0.0).normalized();
82
83 // Accelerate angular speed relative to the length of the mouse sweep
84 qreal acc = diff.length() / 100.0;
85
86 // Calculate new rotation axis as weighted sum
87 rotationAxis = (rotationAxis * angularSpeed + n * acc).normalized();
88
89 // Increase angular speed
90 angularSpeed += acc;
91}
92//! [0]
93
94//! [1]
95void MainWidget::timerEvent(QTimerEvent *)
96{
97 // Decrease angular speed (friction)
98 angularSpeed *= 0.99;
99
100 // Stop rotation when speed goes below threshold
101 if (angularSpeed < 0.01) {
102 angularSpeed = 0.0;
103 } else {
104 // Update rotation
105 rotation = QQuaternion::fromAxisAndAngle(axis: rotationAxis, angle: angularSpeed) * rotation;
106
107 // Request an update
108 update();
109 }
110}
111//! [1]
112
113void MainWidget::initializeGL()
114{
115 initializeOpenGLFunctions();
116
117 glClearColor(red: 0, green: 0, blue: 0, alpha: 1);
118
119 initShaders();
120 initTextures();
121
122//! [2]
123 // Enable depth buffer
124 glEnable(GL_DEPTH_TEST);
125
126 // Enable back face culling
127 glEnable(GL_CULL_FACE);
128//! [2]
129
130 geometries = new GeometryEngine;
131
132 // Use QBasicTimer because its faster than QTimer
133 timer.start(msec: 12, obj: this);
134}
135
136//! [3]
137void MainWidget::initShaders()
138{
139 // Compile vertex shader
140 if (!program.addShaderFromSourceFile(type: QOpenGLShader::Vertex, fileName: ":/vshader.glsl"))
141 close();
142
143 // Compile fragment shader
144 if (!program.addShaderFromSourceFile(type: QOpenGLShader::Fragment, fileName: ":/fshader.glsl"))
145 close();
146
147 // Link shader pipeline
148 if (!program.link())
149 close();
150
151 // Bind shader pipeline for use
152 if (!program.bind())
153 close();
154}
155//! [3]
156
157//! [4]
158void MainWidget::initTextures()
159{
160 // Load cube.png image
161 texture = new QOpenGLTexture(QImage(":/cube.png").mirrored());
162
163 // Set nearest filtering mode for texture minification
164 texture->setMinificationFilter(QOpenGLTexture::Nearest);
165
166 // Set bilinear filtering mode for texture magnification
167 texture->setMagnificationFilter(QOpenGLTexture::Linear);
168
169 // Wrap texture coordinates by repeating
170 // f.ex. texture coordinate (1.1, 1.2) is same as (0.1, 0.2)
171 texture->setWrapMode(QOpenGLTexture::Repeat);
172}
173//! [4]
174
175//! [5]
176void MainWidget::resizeGL(int w, int h)
177{
178 // Calculate aspect ratio
179 qreal aspect = qreal(w) / qreal(h ? h : 1);
180
181 // Set near plane to 3.0, far plane to 7.0, field of view 45 degrees
182 const qreal zNear = 3.0, zFar = 7.0, fov = 45.0;
183
184 // Reset projection
185 projection.setToIdentity();
186
187 // Set perspective projection
188 projection.perspective(verticalAngle: fov, aspectRatio: aspect, nearPlane: zNear, farPlane: zFar);
189}
190//! [5]
191
192void MainWidget::paintGL()
193{
194 // Clear color and depth buffer
195 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
196
197 texture->bind();
198
199//! [6]
200 // Calculate model view transformation
201 QMatrix4x4 matrix;
202 matrix.translate(x: 0.0, y: 0.0, z: -5.0);
203 matrix.rotate(quaternion: rotation);
204
205 // Set modelview-projection matrix
206 program.setUniformValue(name: "mvp_matrix", value: projection * matrix);
207//! [6]
208
209 // Use texture unit 0 which contains cube.png
210 program.setUniformValue(name: "texture", value: 0);
211
212 // Draw cube geometry
213 geometries->drawCubeGeometry(program: &program);
214}
215

source code of qtbase/examples/opengl/cube/mainwidget.cpp