mainwidget.cpp Example File

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#include "mainwidget.h" #include <QMouseEvent> #include <math.h> MainWidget::MainWidget(QWidget *parent) : QOpenGLWidget(parent), geometries(0), texture(0), angularSpeed(0) { } MainWidget::~MainWidget() { // Make sure the context is current when deleting the texture // and the buffers. makeCurrent(); delete texture; delete geometries; doneCurrent(); } void MainWidget::mousePressEvent(QMouseEvent *e) { // Save mouse press position mousePressPosition = QVector2D(e->localPos()); } void MainWidget::mouseReleaseEvent(QMouseEvent *e) { // Mouse release position - mouse press position QVector2D diff = QVector2D(e->localPos()) - mousePressPosition; // Rotation axis is perpendicular to the mouse position difference // vector QVector3D n = QVector3D(diff.y(), diff.x(), 0.0).normalized(); // Accelerate angular speed relative to the length of the mouse sweep qreal acc = diff.length() / 100.0; // Calculate new rotation axis as weighted sum rotationAxis = (rotationAxis * angularSpeed + n * acc).normalized(); // Increase angular speed angularSpeed += acc; } void MainWidget::timerEvent(QTimerEvent *) { // Decrease angular speed (friction) angularSpeed *= 0.99; // Stop rotation when speed goes below threshold if (angularSpeed < 0.01) { angularSpeed = 0.0; } else { // Update rotation rotation = QQuaternion::fromAxisAndAngle(rotationAxis, angularSpeed) * rotation; // Request an update update(); } } void MainWidget::initializeGL() { initializeOpenGLFunctions(); glClearColor(0, 0, 0, 1); initShaders(); initTextures(); // Enable depth buffer glEnable(GL_DEPTH_TEST); // Enable back face culling glEnable(GL_CULL_FACE); geometries = new GeometryEngine; // Use QBasicTimer because its faster than QTimer timer.start(12, this); } void MainWidget::initShaders() { // Compile vertex shader if (!program.addShaderFromSourceFile(QOpenGLShader::Vertex, ":/vshader.glsl")) close(); // Compile fragment shader if (!program.addShaderFromSourceFile(QOpenGLShader::Fragment, ":/fshader.glsl")) close(); // Link shader pipeline if (! close(); // Bind shader pipeline for use if (!program.bind()) close(); } void MainWidget::initTextures() { // Load cube.png image texture = new QOpenGLTexture(QImage(":/cube.png").mirrored()); // Set nearest filtering mode for texture minification texture->setMinificationFilter(QOpenGLTexture::Nearest); // Set bilinear filtering mode for texture magnification texture->setMagnificationFilter(QOpenGLTexture::Linear); // Wrap texture coordinates by repeating // f.ex. texture coordinate (1.1, 1.2) is same as (0.1, 0.2) texture->setWrapMode(QOpenGLTexture::Repeat); } void MainWidget::resizeGL(int w, int h) { // Calculate aspect ratio qreal aspect = qreal(w) / qreal(h ? h : 1); // Set near plane to 3.0, far plane to 7.0, field of view 45 degrees const qreal zNear = 3.0, zFar = 7.0, fov = 45.0; // Reset projection projection.setToIdentity(); // Set perspective projection projection.perspective(fov, aspect, zNear, zFar); } void MainWidget::paintGL() { // Clear color and depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); texture->bind(); // Calculate model view transformation QMatrix4x4 matrix; matrix.translate(0.0, 0.0, -5.0); matrix.rotate(rotation); // Set modelview-projection matrix program.setUniformValue("mvp_matrix", projection * matrix); // Use texture unit 0 which contains cube.png program.setUniformValue("texture", 0); // Draw cube geometry geometries->drawCubeGeometry(&program); }

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