glwindow.cpp Example File

hellogles3/glwindow.cpp
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 #include "glwindow.h"
 #include <QImage>
 #include <QOpenGLTexture>
 #include <QOpenGLShaderProgram>
 #include <QOpenGLBuffer>
 #include <QOpenGLContext>
 #include <QOpenGLVertexArrayObject>
 #include <QOpenGLExtraFunctions>
 #include <QPropertyAnimation>
 #include <QPauseAnimation>
 #include <QSequentialAnimationGroup>
 #include <QTimer>

 GLWindow::GLWindow()
     : m_texture(0),
       m_program(0),
       m_vbo(0),
       m_vao(0),
       m_target(0, 0, -1),
       m_uniformsDirty(true),
       m_r(0),
       m_r2(0)
 {
     m_world.setToIdentity();
     m_world.translate(0, 0, -1);
     m_world.rotate(180, 1, 0, 0);

     QSequentialAnimationGroup *animGroup = new QSequentialAnimationGroup(this);
     animGroup->setLoopCount(-1);
     QPropertyAnimation *zAnim0 = new QPropertyAnimation(this, QByteArrayLiteral("z"));
     zAnim0->setStartValue(1.5f);
     zAnim0->setEndValue(10.0f);
     zAnim0->setDuration(2000);
     animGroup->addAnimation(zAnim0);
     QPropertyAnimation *zAnim1 = new QPropertyAnimation(this, QByteArrayLiteral("z"));
     zAnim1->setStartValue(10.0f);
     zAnim1->setEndValue(50.0f);
     zAnim1->setDuration(4000);
     zAnim1->setEasingCurve(QEasingCurve::OutElastic);
     animGroup->addAnimation(zAnim1);
     QPropertyAnimation *zAnim2 = new QPropertyAnimation(this, QByteArrayLiteral("z"));
     zAnim2->setStartValue(50.0f);
     zAnim2->setEndValue(1.5f);
     zAnim2->setDuration(2000);
     animGroup->addAnimation(zAnim2);
     animGroup->start();

     QPropertyAnimation* rAnim = new QPropertyAnimation(this, QByteArrayLiteral("r"));
     rAnim->setStartValue(0.0f);
     rAnim->setEndValue(360.0f);
     rAnim->setDuration(2000);
     rAnim->setLoopCount(-1);
     rAnim->start();

     QTimer::singleShot(4000, this, &GLWindow::startSecondStage);
 }

 GLWindow::~GLWindow()
 {
     makeCurrent();
     delete m_texture;
     delete m_program;
     delete m_vbo;
     delete m_vao;
 }

 void GLWindow::startSecondStage()
 {
     QPropertyAnimation* r2Anim = new QPropertyAnimation(this, QByteArrayLiteral("r2"));
     r2Anim->setStartValue(0.0f);
     r2Anim->setEndValue(360.0f);
     r2Anim->setDuration(20000);
     r2Anim->setLoopCount(-1);
     r2Anim->start();
 }

 void GLWindow::setZ(float v)
 {
     m_eye.setZ(v);
     m_uniformsDirty = true;
     update();
 }

 void GLWindow::setR(float v)
 {
     m_r = v;
     m_uniformsDirty = true;
     update();
 }

 void GLWindow::setR2(float v)
 {
     m_r2 = v;
     m_uniformsDirty = true;
     update();
 }

 static const char *vertexShaderSource =
     "layout(location = 0) in vec4 vertex;\n"
     "layout(location = 1) in vec3 normal;\n"
     "out vec3 vert;\n"
     "out vec3 vertNormal;\n"
     "out vec3 color;\n"
     "uniform mat4 projMatrix;\n"
     "uniform mat4 camMatrix;\n"
     "uniform mat4 worldMatrix;\n"
     "uniform mat4 myMatrix;\n"
     "uniform sampler2D sampler;\n"
     "void main() {\n"
     "   ivec2 pos = ivec2(gl_InstanceID % 32, gl_InstanceID / 32);\n"
     "   vec2 t = vec2(float(-16 + pos.x) * 0.8, float(-18 + pos.y) * 0.6);\n"
     "   float val = 2.0 * length(texelFetch(sampler, pos, 0).rgb);\n"
     "   mat4 wm = myMatrix * mat4(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, t.x, t.y, val, 1) * worldMatrix;\n"
     "   color = texelFetch(sampler, pos, 0).rgb * vec3(0.4, 1.0, 0.0);\n"
     "   vert = vec3(wm * vertex);\n"
     "   vertNormal = mat3(transpose(inverse(wm))) * normal;\n"
     "   gl_Position = projMatrix * camMatrix * wm * vertex;\n"
     "}\n";

 static const char *fragmentShaderSource =
     "in highp vec3 vert;\n"
     "in highp vec3 vertNormal;\n"
     "in highp vec3 color;\n"
     "out highp vec4 fragColor;\n"
     "uniform highp vec3 lightPos;\n"
     "void main() {\n"
     "   highp vec3 L = normalize(lightPos - vert);\n"
     "   highp float NL = max(dot(normalize(vertNormal), L), 0.0);\n"
     "   highp vec3 col = clamp(color * 0.2 + color * 0.8 * NL, 0.0, 1.0);\n"
     "   fragColor = vec4(col, 1.0);\n"
     "}\n";

 QByteArray versionedShaderCode(const char *src)
 {
     QByteArray versionedSrc;

     if (QOpenGLContext::currentContext()->isOpenGLES())
         versionedSrc.append(QByteArrayLiteral("#version 300 es\n"));
     else
         versionedSrc.append(QByteArrayLiteral("#version 330\n"));

     versionedSrc.append(src);
     return versionedSrc;
 }

 void GLWindow::initializeGL()
 {
     QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();

     if (m_texture) {
         delete m_texture;
         m_texture = 0;
     }
     QImage img(":/qtlogo.png");
     Q_ASSERT(!img.isNull());
     m_texture = new QOpenGLTexture(img.scaled(32, 36).mirrored());

     if (m_program) {
         delete m_program;
         m_program = 0;
     }
     m_program = new QOpenGLShaderProgram;
     // Prepend the correct version directive to the sources. The rest is the
     // same, thanks to the common GLSL syntax.
     m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, versionedShaderCode(vertexShaderSource));
     m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, versionedShaderCode(fragmentShaderSource));
     m_program->link();

     m_projMatrixLoc = m_program->uniformLocation("projMatrix");
     m_camMatrixLoc = m_program->uniformLocation("camMatrix");
     m_worldMatrixLoc = m_program->uniformLocation("worldMatrix");
     m_myMatrixLoc = m_program->uniformLocation("myMatrix");
     m_lightPosLoc = m_program->uniformLocation("lightPos");

     // Create a VAO. Not strictly required for ES 3, but it is for plain OpenGL.
     if (m_vao) {
         delete m_vao;
         m_vao = 0;
     }
     m_vao = new QOpenGLVertexArrayObject;
     if (m_vao->create())
         m_vao->bind();

     if (m_vbo) {
         delete m_vbo;
         m_vbo = 0;
     }
     m_program->bind();
     m_vbo = new QOpenGLBuffer;
     m_vbo->create();
     m_vbo->bind();
     m_vbo->allocate(m_logo.constData(), m_logo.count() * sizeof(GLfloat));
     f->glEnableVertexAttribArray(0);
     f->glEnableVertexAttribArray(1);
     f->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), 0);
     f->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat),
                              reinterpret_cast<void *>(3 * sizeof(GLfloat)));
     m_vbo->release();

     f->glEnable(GL_DEPTH_TEST);
     f->glEnable(GL_CULL_FACE);
 }

 void GLWindow::resizeGL(int w, int h)
 {
     m_proj.setToIdentity();
     m_proj.perspective(45.0f, GLfloat(w) / h, 0.01f, 100.0f);
     m_uniformsDirty = true;
 }

 void GLWindow::paintGL()
 {
     // Now use QOpenGLExtraFunctions instead of QOpenGLFunctions as we want to
     // do more than what GL(ES) 2.0 offers.
     QOpenGLExtraFunctions *f = QOpenGLContext::currentContext()->extraFunctions();

     f->glClearColor(0, 0, 0, 1);
     f->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

     m_program->bind();
     m_texture->bind();

     if (m_uniformsDirty) {
         m_uniformsDirty = false;
         QMatrix4x4 camera;
         camera.lookAt(m_eye, m_eye + m_target, QVector3D(0, 1, 0));
         m_program->setUniformValue(m_projMatrixLoc, m_proj);
         m_program->setUniformValue(m_camMatrixLoc, camera);
         QMatrix4x4 wm = m_world;
         wm.rotate(m_r, 1, 1, 0);
         m_program->setUniformValue(m_worldMatrixLoc, wm);
         QMatrix4x4 mm;
         mm.setToIdentity();
         mm.rotate(-m_r2, 1, 0, 0);
         m_program->setUniformValue(m_myMatrixLoc, mm);
         m_program->setUniformValue(m_lightPosLoc, QVector3D(0, 0, 70));
     }

     // Now call a function introduced in OpenGL 3.1 / OpenGL ES 3.0. We
     // requested a 3.3 or ES 3.0 context, so we know this will work.
     f->glDrawArraysInstanced(GL_TRIANGLES, 0, m_logo.vertexCount(), 32 * 36);
 }