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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include "mainwidget.h"
#include <QMouseEvent>
#include <cmath>
MainWidget::~MainWidget()
{
// Make sure the context is current when deleting the texture
// and the buffers.
makeCurrent();
delete texture;
delete geometries;
doneCurrent();
}
//! [0]
void MainWidget::mousePressEvent(QMouseEvent *e)
{
// Save mouse press position
mousePressPosition = QVector2D(e->position());
}
void MainWidget::mouseReleaseEvent(QMouseEvent *e)
{
// Mouse release position - mouse press position
QVector2D diff = QVector2D(e->position()) - 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;
}
//! [0]
//! [1]
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();
}
}
//! [1]
void MainWidget::initializeGL()
{
initializeOpenGLFunctions();
glClearColor(0, 0, 0, 1);
initShaders();
initTextures();
geometries = new GeometryEngine;
// Use QBasicTimer because its faster than QTimer
timer.start(12, this);
}
//! [3]
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 (!program.link())
close();
// Bind shader pipeline for use
if (!program.bind())
close();
}
//! [3]
//! [4]
void MainWidget::initTextures()
{
// Load cube.png image
texture = new QOpenGLTexture(QImage(":/cube.png").flipped());
// 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);
}
//! [4]
//! [5]
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);
}
//! [5]
void MainWidget::paintGL()
{
// Clear color and depth buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//! [2]
// Enable depth buffer
glEnable(GL_DEPTH_TEST);
// Enable back face culling
glEnable(GL_CULL_FACE);
//! [2]
texture->bind();
program.bind();
//! [6]
// 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);
//! [6]
// Use texture unit 0 which contains cube.png
program.setUniformValue("texture", 0);
// Draw cube geometry
geometries->drawCubeGeometry(&program);
}
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