OpenGL w/ Qt5

mainwindow.cpp

#include "mainwindow.h"

#include <QtGui/QMatrix4x4>
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QScreen>
#include <QGLContext>

MainWindow::MainWindow() :
    m_program(0)
  , m_frame(0)
{
}

MainWindow::~MainWindow()
{
    if ( m_texture )
    {
        glDeleteTextures( 1, &m_texture );
        m_texture = 0;
    }
}

/*static const char *vertexShaderSource =
    "attribute highp vec4 posAttr;\n"
    "attribute lowp vec4 colAttr;\n"
    "varying lowp vec4 col;\n"
    "uniform highp mat4 matrix;\n"
    "void main() {\n"
    "   col = colAttr;\n"
    "   gl_Position = matrix * posAttr;\n"
    "}\n";*/

static const char *vertexTxtShaderSource =
    "attribute highp vec4 posAttr;\n"
    "attribute mediump vec4 texCoord;\n"
    "varying mediump vec4 texc;\n"
    "uniform highp mat4 matrix;\n"
    "void main() {\n"
    "   texc = texCoord;\n"
    "   gl_Position = matrix * posAttr;\n"
    "}\n";

/*static const char *fragmentShaderSource =
    "varying lowp vec4 col;\n"
    "void main() {\n"
    "   gl_FragColor = col;\n"
    "}\n";*/

static const char *fragmentTxtShaderSource =
    "uniform sampler2D texture;\n"
    "varying mediump vec4 texc;\n"
    "void main() {\n"
    "   gl_FragColor = texture2D(texture, texc.st);\n"
    "}\n";

GLuint MainWindow::loadShader(GLenum type, const char *source)
{
    GLuint shader = glCreateShader(type);
    glShaderSource(shader, 1, &source, 0);
    glCompileShader(shader);
    return shader;
}

void MainWindow::initialize()
{

    glEnable(GL_TEXTURE_2D);
    m_program = new QOpenGLShaderProgram(this);
    //m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexShaderSource);
    //m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentShaderSource);
    m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexTxtShaderSource);
    m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentTxtShaderSource);
    m_program->link();
    m_posAttr = m_program->attributeLocation("posAttr");
    //m_colAttr = m_program->attributeLocation("colAttr");
    m_texCoord = m_program->attributeLocation("texCoord");
    m_matrixUniform = m_program->uniformLocation("matrix");

    m_program->setUniformValue("texture", 0);
    m_texture = QGLContext::fromOpenGLContext(getContext())->bindTexture(QImage("Caisse.jpg"), GL_TEXTURE_2D);
}

void MainWindow::render()
{
    const qreal retinaScale = devicePixelRatio();
    glViewport(0, 0, width() * retinaScale, height() * retinaScale);

    glClear(GL_COLOR_BUFFER_BIT);

    m_program->bind();

    QMatrix4x4 matrix;
    matrix.perspective(60, 4.0/3.0, 0.1, 100.0);
    matrix.translate(0, 0, -2);
    matrix.rotate(100.0f * m_frame / screen()->refreshRate(), 0, 1, 0.1f);

    m_program->setUniformValue(m_matrixUniform, matrix);

    GLfloat vertices[] = {
        0.0f, 0.707f,
        -0.5f, -0.5f,
        0.5f, -0.5f,
    };

    /*GLfloat colors[] = {
        1.0f, 0.0f, 0.0f,
        0.0f, 1.0f, 0.0f,
        0.0f, 0.0f, 1.0f
    };*/

    glVertexAttribPointer(m_posAttr, 2, GL_FLOAT, GL_FALSE, 0, vertices);
    glVertexAttribPointer(m_texCoord, 2, GL_FLOAT, GL_FALSE, 0, vertices);
    //glVertexAttribPointer(m_colAttr, 3, GL_FLOAT, GL_FALSE, 0, colors);

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);

    glBindTexture(GL_TEXTURE_2D, m_texture);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    glBindTexture(GL_TEXTURE_2D, 0);

    glDisableVertexAttribArray(1);
    glDisableVertexAttribArray(0);

    m_program->release();

    ++m_frame;
}