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);
  }