glwidget.cpp Example File

textures/glwidget.cpp
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#include "glwidget.h" #include <QOpenGLShaderProgram> #include <QOpenGLTexture> #include <QMouseEvent> GLWidget::GLWidget(QWidget *parent) : QOpenGLWidget(parent), clearColor(Qt::black), xRot(0), yRot(0), zRot(0), program(0) { memset(textures, 0, sizeof(textures)); } GLWidget::~GLWidget() { makeCurrent(); vbo.destroy(); for (int i = 0; i < 6; ++i) delete textures[i]; delete program; doneCurrent(); } QSize GLWidget::minimumSizeHint() const { return QSize(50, 50); } QSize GLWidget::sizeHint() const { return QSize(200, 200); } void GLWidget::rotateBy(int xAngle, int yAngle, int zAngle) { xRot += xAngle; yRot += yAngle; zRot += zAngle; update(); } void GLWidget::setClearColor(const QColor &color) { clearColor = color; update(); } void GLWidget::initializeGL() { initializeOpenGLFunctions(); makeObject(); glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); #define PROGRAM_VERTEX_ATTRIBUTE 0 #define PROGRAM_TEXCOORD_ATTRIBUTE 1 QOpenGLShader *vshader = new QOpenGLShader(QOpenGLShader::Vertex, this); const char *vsrc = "attribute highp vec4 vertex;\n" "attribute mediump vec4 texCoord;\n" "varying mediump vec4 texc;\n" "uniform mediump mat4 matrix;\n" "void main(void)\n" "{\n" " gl_Position = matrix * vertex;\n" " texc = texCoord;\n" "}\n"; vshader->compileSourceCode(vsrc); QOpenGLShader *fshader = new QOpenGLShader(QOpenGLShader::Fragment, this); const char *fsrc = "uniform sampler2D texture;\n" "varying mediump vec4 texc;\n" "void main(void)\n" "{\n" " gl_FragColor = texture2D(texture, texc.st);\n" "}\n"; fshader->compileSourceCode(fsrc); program = new QOpenGLShaderProgram; program->addShader(vshader); program->addShader(fshader); program->bindAttributeLocation("vertex", PROGRAM_VERTEX_ATTRIBUTE); program->bindAttributeLocation("texCoord", PROGRAM_TEXCOORD_ATTRIBUTE); program->link(); program->bind(); program->setUniformValue("texture", 0); } void GLWidget::paintGL() { glClearColor(clearColor.redF(), clearColor.greenF(), clearColor.blueF(), clearColor.alphaF()); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); QMatrix4x4 m; m.ortho(-0.5f, +0.5f, +0.5f, -0.5f, 4.0f, 15.0f); m.translate(0.0f, 0.0f, -10.0f); m.rotate(xRot / 16.0f, 1.0f, 0.0f, 0.0f); m.rotate(yRot / 16.0f, 0.0f, 1.0f, 0.0f); m.rotate(zRot / 16.0f, 0.0f, 0.0f, 1.0f); program->setUniformValue("matrix", m); program->enableAttributeArray(PROGRAM_VERTEX_ATTRIBUTE); program->enableAttributeArray(PROGRAM_TEXCOORD_ATTRIBUTE); program->setAttributeBuffer(PROGRAM_VERTEX_ATTRIBUTE, GL_FLOAT, 0, 3, 5 * sizeof(GLfloat)); program->setAttributeBuffer(PROGRAM_TEXCOORD_ATTRIBUTE, GL_FLOAT, 3 * sizeof(GLfloat), 2, 5 * sizeof(GLfloat)); for (int i = 0; i < 6; ++i) { textures[i]->bind(); glDrawArrays(GL_TRIANGLE_FAN, i * 4, 4); } } void GLWidget::resizeGL(int width, int height) { int side = qMin(width, height); glViewport((width - side) / 2, (height - side) / 2, side, side); } void GLWidget::mousePressEvent(QMouseEvent *event) { lastPos = event->pos(); } void GLWidget::mouseMoveEvent(QMouseEvent *event) { int dx = event->x() - lastPos.x(); int dy = event->y() - lastPos.y(); if (event->buttons() & Qt::LeftButton) { rotateBy(8 * dy, 8 * dx, 0); } else if (event->buttons() & Qt::RightButton) { rotateBy(8 * dy, 0, 8 * dx); } lastPos = event->pos(); } void GLWidget::mouseReleaseEvent(QMouseEvent * /* event */) { emit clicked(); } void GLWidget::makeObject() { static const int coords[6][4][3] = { { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } }, { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } }, { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } }, { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } }, { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } }, { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } } }; for (int j = 0; j < 6; ++j) textures[j] = new QOpenGLTexture(QImage(QString(":/images/side%1.png").arg(j + 1)).mirrored()); QVector<GLfloat> vertData; for (int i = 0; i < 6; ++i) { for (int j = 0; j < 4; ++j) { // vertex position vertData.append(0.2 * coords[i][j][0]); vertData.append(0.2 * coords[i][j][1]); vertData.append(0.2 * coords[i][j][2]); // texture coordinate vertData.append(j == 0 || j == 3); vertData.append(j == 0 || j == 1); } } vbo.create(); vbo.bind(); vbo.allocate(vertData.constData(), vertData.count() * sizeof(GLfloat)); }