Do offscreen render(openGL) with Qt5

**stereoMatching** · 23rd June 2013, 02:06

I want to do offscreen rendering, but have no luck
These are the codes, I have no any idea why the FBO(frame buffer object)
always give me a blank image

What I want to do is, the texture after render will write to the FBO
after that, I could transfer the data of fbo into QImage by toImage()

.hpp

Qt Code:

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#ifndef OFFSCREENEXP_HPP
#define OFFSCREENEXP_HPP
 
#include <QOpenGLFunctions>
#include <QWindow>
 
class QImage;
class QOpenGLContext;
 
class offScreenExp : public QWindow, protected QOpenGLFunctions
{
public:
    explicit offScreenExp(QWindow *parent = 0);
 
    QImage render();
 
private:
    QOpenGLContext *context_;
};
 
#endif // OFFSCREENEXP_HPP

#ifndef OFFSCREENEXP_HPP
#define OFFSCREENEXP_HPP

#include <QOpenGLFunctions>
#include <QWindow>

class QImage;
class QOpenGLContext;

class offScreenExp : public QWindow, protected QOpenGLFunctions
{
public:
    explicit offScreenExp(QWindow *parent = 0);

    QImage render();

private:
    QOpenGLContext *context_;
};

#endif // OFFSCREENEXP_HPP

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.cpp

Qt Code:

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#include <QImage>
#include <QOpenGLBuffer>
#include <QOpenGLContext>
#include <QOpenGLFramebufferObject>
#include <QOpenGLShaderProgram>
#include <QString>
#include <QWidget>
 
#include <QDebug>
 
#include "offScreenExp.hpp"
 
offScreenExp::offScreenExp(QWindow *parent) :
    QWindow(parent),
    context_(nullptr)
{
    setSurfaceType(QWindow::OpenGLSurface);
    setFormat(QSurfaceFormat());
    create();
}
 
QImage offScreenExp::render()
{
    //create the context
    if (!context_) {
        context_ = new QOpenGLContext(this);
        QSurfaceFormat format;
        context_->setFormat(format);
 
        if (!context_->create())
            qFatal("Cannot create the requested OpenGL context!");
    }
 
    context_->makeCurrent(this);
    initializeOpenGLFunctions();
 
    //load image
    QString const prefix("/Users/Qt/program/experiment_apps_and_libs/openGLTest/simpleGPGPU/");
    QImage img(prefix + "images/emili.jpg");
    if(img.isNull()){
      qFatal("image is null");
    }    
 
    //if(glCheckFramebufferStatus(fbo.handle()) != GL_FRAMEBUFFER_COMPLETE){
    //    qDebug()<<"frame buffer error";
    //}
    qDebug()<<"has opengl fbo : "<<QOpenGLFramebufferObject::hasOpenGLFramebufferObjects();
 
    //use two triangles two cover whole screen
    std::vector<GLfloat> const vertex{
        -1.0f,  1.0f, 0.0f, 1.0f,
        1.0f,  1.0f, 0.0f, 1.0f,
        -1.0f, -1.0f, 0.0f, 1.0f,
        1.0f, 1.0f, 0.0f, 1.0f,
        1.0f, -1.0f, 0.0f, 1.0f,
        -1.0f, -1.0f, 0.0f, 1.0f,
    };
 
    //initialize vbo
    QOpenGLBuffer buffer(QOpenGLBuffer::VertexBuffer);
    buffer.create();
    buffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
    buffer.bind();
    buffer.allocate(&vertex[0], vertex.size() * sizeof(GLfloat) );
    buffer.release();
 
    //create texture
    GLuint rendered_texture;
    glGenTextures(1, &rendered_texture);
 
    // "Bind" the newly created texture : all future texture functions will modify this texture
    glBindTexture(GL_TEXTURE_2D, rendered_texture);
 
    //naive solution, better encapsulate the format in a function
    if(img.format() == QImage::Format_Indexed8){
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, img.width(), img.height(), 0, GL_RED, GL_UNSIGNED_BYTE, img.scanLine(0));
    }else if(img.format() == QImage::Format_RGB888){
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.width(), img.height(), 0, GL_RGB, GL_UNSIGNED_BYTE, img.scanLine(0));
    }else{
        QImage temp = img.convertToFormat(QImage::Format_RGB888);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.width(), img.height(), 0, GL_RGB, GL_UNSIGNED_BYTE, temp.scanLine(0));
    }
 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
    glBindTexture(GL_TEXTURE_2D, 0);
 
    //compile and link program
    QOpenGLShaderProgram program;
    if(!program.addShaderFromSourceCode(QOpenGLShader::Vertex,
                                        "attribute highp vec4 qt_Vertex;"
                                        "varying highp vec2 qt_TexCoord0;"
 
                                        "void main(void)"
                                        "{"
                                        "   gl_Position =  qt_Vertex;"
                                        "   qt_TexCoord0 = (qt_Vertex.xy + vec2(1.0)) * 0.5;"
                                        "}")){
        qDebug()<<"QOpenGLShader::Vertex error : " + program.log();
    }
 
    // Compile fragment shader
    if (!program.addShaderFromSourceCode(QOpenGLShader::Fragment,
                                         "uniform sampler2D source;"
                                         "varying highp vec2 qt_TexCoord0;"
 
                                         "vec3 toGray(vec3 rgb)"
                                         "{"
                                         " return vec3(rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);"
                                         "}"
 
                                         "void main(void)"
                                         "{"
                                         "vec3 gray = toGray(texture2D(source, qt_TexCoord0).rgb);"
                                         "gl_FragColor = vec4(gray, 0.0);"
                                         "}"
                                         )){
        qDebug()<<"QOpenGLShader::Fragment error : " + program.log();
    }
 
    // Link shader pipeline
    if (!program.link()){
        qDebug()<<"link error : " + program.log();
    }
 
    //render the texture as usual
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, img.width(), img.height());
 
    program.bind();
    buffer.bind();
    program.enableAttributeArray("qt_Vertex");
    program.setAttributeBuffer( "qt_Vertex", GL_FLOAT, 0, 4);
 
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, rendered_texture);
 
    //bind and create fbo
    QOpenGLFramebufferObject fbo(img.size());
    qDebug()<<"bind success? : "<<fbo.bind();
 
    glDrawArrays(GL_TRIANGLES, 0, buffer.size());
 
    program.disableAttributeArray("qt_Vertex");
    program.release();
    glActiveTexture(0);
    glBindTexture(GL_TEXTURE_2D, 0);
    buffer.release();
 
    QImage result = fbo.toImage();
    fbo.release();
    context_->doneCurrent();
 
    return result;
}

#include <QImage>
#include <QOpenGLBuffer>
#include <QOpenGLContext>
#include <QOpenGLFramebufferObject>
#include <QOpenGLShaderProgram>
#include <QString>
#include <QWidget>

#include <QDebug>

#include "offScreenExp.hpp"

offScreenExp::offScreenExp(QWindow *parent) :
    QWindow(parent),
    context_(nullptr)
{
    setSurfaceType(QWindow::OpenGLSurface);
    setFormat(QSurfaceFormat());
    create();
}

QImage offScreenExp::render()
{
    //create the context
    if (!context_) {
        context_ = new QOpenGLContext(this);
        QSurfaceFormat format;
        context_->setFormat(format);

        if (!context_->create())
            qFatal("Cannot create the requested OpenGL context!");
    }

    context_->makeCurrent(this);
    initializeOpenGLFunctions();

    //load image
    QString const prefix("/Users/Qt/program/experiment_apps_and_libs/openGLTest/simpleGPGPU/");
    QImage img(prefix + "images/emili.jpg");
    if(img.isNull()){
      qFatal("image is null");
    }    

    //if(glCheckFramebufferStatus(fbo.handle()) != GL_FRAMEBUFFER_COMPLETE){
    //    qDebug()<<"frame buffer error";
    //}
    qDebug()<<"has opengl fbo : "<<QOpenGLFramebufferObject::hasOpenGLFramebufferObjects();

    //use two triangles two cover whole screen
    std::vector<GLfloat> const vertex{
        -1.0f,  1.0f, 0.0f, 1.0f,
        1.0f,  1.0f, 0.0f, 1.0f,
        -1.0f, -1.0f, 0.0f, 1.0f,
        1.0f, 1.0f, 0.0f, 1.0f,
        1.0f, -1.0f, 0.0f, 1.0f,
        -1.0f, -1.0f, 0.0f, 1.0f,
    };

    //initialize vbo
    QOpenGLBuffer buffer(QOpenGLBuffer::VertexBuffer);
    buffer.create();
    buffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
    buffer.bind();
    buffer.allocate(&vertex[0], vertex.size() * sizeof(GLfloat) );
    buffer.release();

    //create texture
    GLuint rendered_texture;
    glGenTextures(1, &rendered_texture);

    // "Bind" the newly created texture : all future texture functions will modify this texture
    glBindTexture(GL_TEXTURE_2D, rendered_texture);

    //naive solution, better encapsulate the format in a function
    if(img.format() == QImage::Format_Indexed8){
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, img.width(), img.height(), 0, GL_RED, GL_UNSIGNED_BYTE, img.scanLine(0));
    }else if(img.format() == QImage::Format_RGB888){
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.width(), img.height(), 0, GL_RGB, GL_UNSIGNED_BYTE, img.scanLine(0));
    }else{
        QImage temp = img.convertToFormat(QImage::Format_RGB888);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.width(), img.height(), 0, GL_RGB, GL_UNSIGNED_BYTE, temp.scanLine(0));
    }

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glBindTexture(GL_TEXTURE_2D, 0);

    //compile and link program
    QOpenGLShaderProgram program;
    if(!program.addShaderFromSourceCode(QOpenGLShader::Vertex,
                                        "attribute highp vec4 qt_Vertex;"
                                        "varying highp vec2 qt_TexCoord0;"

                                        "void main(void)"
                                        "{"
                                        "   gl_Position =  qt_Vertex;"
                                        "   qt_TexCoord0 = (qt_Vertex.xy + vec2(1.0)) * 0.5;"
                                        "}")){
        qDebug()<<"QOpenGLShader::Vertex error : " + program.log();
    }

    // Compile fragment shader
    if (!program.addShaderFromSourceCode(QOpenGLShader::Fragment,
                                         "uniform sampler2D source;"
                                         "varying highp vec2 qt_TexCoord0;"

                                         "vec3 toGray(vec3 rgb)"
                                         "{"
                                         " return vec3(rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);"
                                         "}"

                                         "void main(void)"
                                         "{"
                                         "vec3 gray = toGray(texture2D(source, qt_TexCoord0).rgb);"
                                         "gl_FragColor = vec4(gray, 0.0);"
                                         "}"
                                         )){
        qDebug()<<"QOpenGLShader::Fragment error : " + program.log();
    }

    // Link shader pipeline
    if (!program.link()){
        qDebug()<<"link error : " + program.log();
    }

    //render the texture as usual
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, img.width(), img.height());

    program.bind();
    buffer.bind();
    program.enableAttributeArray("qt_Vertex");
    program.setAttributeBuffer( "qt_Vertex", GL_FLOAT, 0, 4);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, rendered_texture);

    //bind and create fbo
    QOpenGLFramebufferObject fbo(img.size());
    qDebug()<<"bind success? : "<<fbo.bind();

    glDrawArrays(GL_TRIANGLES, 0, buffer.size());

    program.disableAttributeArray("qt_Vertex");
    program.release();
    glActiveTexture(0);
    glBindTexture(GL_TEXTURE_2D, 0);
    buffer.release();

    QImage result = fbo.toImage();
    fbo.release();
    context_->doneCurrent();

    return result;
}

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**saman_artorious** · 23rd June 2013, 11:45

your fbo implementation is correct. But, may I ask why you are using 0 here:

glBindTexture(GL_TEXTURE_2D, 0);

**stereoMatching** · 23rd June 2013, 15:20

Thanks for your reply, I unbind the texture too early.

Qt Code:

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//render the texture as usual
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, img.width(), img.height());
 
    program.bind();
    buffer.bind();
    program.enableAttributeArray("qt_Vertex");
    program.setAttributeBuffer( "qt_Vertex", GL_FLOAT, 0, 4);
 
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, rendered_texture);
 
    //bind and create fbo
    QOpenGLFramebufferObject fbo(img.size());
    qDebug()<<"bind success? : "<<fbo.bind();
 
    glDrawArrays(GL_TRIANGLES, 0, buffer.size());
    QImage result = fbo.toImage();
 
    program.disableAttributeArray("qt_Vertex");
    program.release();    
    buffer.release();
 
    fbo.release();
    glActiveTexture(0);
    glBindTexture(GL_TEXTURE_2D, 0);
    context_->doneCurrent();

//render the texture as usual
    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, img.width(), img.height());

    program.bind();
    buffer.bind();
    program.enableAttributeArray("qt_Vertex");
    program.setAttributeBuffer( "qt_Vertex", GL_FLOAT, 0, 4);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, rendered_texture);

    //bind and create fbo
    QOpenGLFramebufferObject fbo(img.size());
    qDebug()<<"bind success? : "<<fbo.bind();

    glDrawArrays(GL_TRIANGLES, 0, buffer.size());
    QImage result = fbo.toImage();

    program.disableAttributeArray("qt_Vertex");
    program.release();    
    buffer.release();

    fbo.release();
    glActiveTexture(0);
    glBindTexture(GL_TEXTURE_2D, 0);
    context_->doneCurrent();

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I change the order of the line(the original can't edit), but I still get a blank image

**saman_artorious** · 25th June 2013, 05:54

can't you test your fbo instructions separately in another program? You may also have a look at my own fbo implementation sample (ignore the lighting part of the program):

Qt Code:

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void GlWidget::paintGL()
{
    BakeDynamicTexture();
 
//    RenderShapes();
 
    glClearColor(0, 0, 0.0f, 1.0f);
    //    //! [2]
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, width(),height());
 
    QMatrix4x4 mMatrix;
    QMatrix4x4 vMatrix;
 
    QMatrix4x4 cameraTransformation;
    cameraTransformation.rotate(alpha, 0, 1, 0);
    cameraTransformation.rotate(beta, 1, 0, 0);
 
    QVector3D cameraPosition = cameraTransformation * QVector3D(0, 0, distance);
    QVector3D cameraUpDirection = cameraTransformation * QVector3D(0, 1, 0);
    vMatrix.lookAt(cameraPosition, QVector3D(0, 0, 0), cameraUpDirection);
 
    QMatrix4x4 mvMatrix;
    mMatrix.setToIdentity();
 
    mvMatrix = vMatrix * mMatrix;
 
    QMatrix3x3 normalMatrix;
    normalMatrix = mvMatrix.normalMatrix();
 
    QMatrix4x4 lightTransformation;
    lightTransformation.rotate(lightAngle, 0, 1, 0);
 
    QVector3D lightPosition = lightTransformation * QVector3D(0, 1, 1);
 
    //! [3]
    //##########################
    //    lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
    //    shpFill->RenderCube       (&lightingShaderProgram, dynamicTexture);
    //    lightingShaderProgram.release();
    //##########################
 
    //! [5]
    lightingShaderProgram.bind();
 
    lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * mvMatrix);
    lightingShaderProgram.setUniformValue("mvMatrix", mvMatrix);
    lightingShaderProgram.setUniformValue("normalMatrix", normalMatrix);
    lightingShaderProgram.setUniformValue("lightPosition", vMatrix * lightPosition);
 
    shpFill->RenderLightingCube(&lightingShaderProgram, dynamicTexture);
 
    mMatrix.setToIdentity();
    mMatrix.translate(lightPosition);
    mMatrix.rotate(lightAngle, 0, 1, 0);
    mMatrix.rotate(45, 1, 0, 0);
    mMatrix.scale(0.1);
 
    coloringShaderProgram.bind();
    coloringShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
 
    shpFill->colorLightingCube(&coloringShaderProgram);
}

void GlWidget::paintGL()
{
    BakeDynamicTexture();

//    RenderShapes();

    glClearColor(0, 0, 0.0f, 1.0f);
    //    //! [2]
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, width(),height());

    QMatrix4x4 mMatrix;
    QMatrix4x4 vMatrix;

    QMatrix4x4 cameraTransformation;
    cameraTransformation.rotate(alpha, 0, 1, 0);
    cameraTransformation.rotate(beta, 1, 0, 0);

    QVector3D cameraPosition = cameraTransformation * QVector3D(0, 0, distance);
    QVector3D cameraUpDirection = cameraTransformation * QVector3D(0, 1, 0);
    vMatrix.lookAt(cameraPosition, QVector3D(0, 0, 0), cameraUpDirection);

    QMatrix4x4 mvMatrix;
    mMatrix.setToIdentity();

    mvMatrix = vMatrix * mMatrix;

    QMatrix3x3 normalMatrix;
    normalMatrix = mvMatrix.normalMatrix();

    QMatrix4x4 lightTransformation;
    lightTransformation.rotate(lightAngle, 0, 1, 0);

    QVector3D lightPosition = lightTransformation * QVector3D(0, 1, 1);

    //! [3]
    //##########################
    //    lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
    //    shpFill->RenderCube       (&lightingShaderProgram, dynamicTexture);
    //    lightingShaderProgram.release();
    //##########################

    //! [5]
    lightingShaderProgram.bind();

    lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * mvMatrix);
    lightingShaderProgram.setUniformValue("mvMatrix", mvMatrix);
    lightingShaderProgram.setUniformValue("normalMatrix", normalMatrix);
    lightingShaderProgram.setUniformValue("lightPosition", vMatrix * lightPosition);

    shpFill->RenderLightingCube(&lightingShaderProgram, dynamicTexture);

    mMatrix.setToIdentity();
    mMatrix.translate(lightPosition);
    mMatrix.rotate(lightAngle, 0, 1, 0);
    mMatrix.rotate(45, 1, 0, 0);
    mMatrix.scale(0.1);

    coloringShaderProgram.bind();
    coloringShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);

    shpFill->colorLightingCube(&coloringShaderProgram);
}

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Baking part:

Qt Code:

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void GlWidget::BakeDynamicTexture()
{
    fbo->bind();
 
    RenderShapes();
 
    fbo->release();
 
    dynamicTexture = fbo->texture();
}

void GlWidget::BakeDynamicTexture()
{
    fbo->bind();

    RenderShapes();

    fbo->release();

    dynamicTexture = fbo->texture();
}

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RenderShapes (instead of drawing a shape file here, simply draw something else, check if it draws successfully)

Qt Code:

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void GlWidget::RenderShapes()
{
    QMatrix4x4 sMatrix;
 
    glClearColor(0.1f, 0.5f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, 256,256);
 
    shaderProgram.bind();
 
    sMatrix.setToIdentity();
 
    shaderProgram.setUniformValue("mvpMatrix", sMatrix);
 
    shpFill->Render(&shaderProgram);
 
    shaderProgram.release();
}

void GlWidget::RenderShapes()
{
    QMatrix4x4 sMatrix;

    glClearColor(0.1f, 0.5f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, 256,256);

    shaderProgram.bind();

    sMatrix.setToIdentity();

    shaderProgram.setUniformValue("mvpMatrix", sMatrix);

    shpFill->Render(&shaderProgram);

    shaderProgram.release();
}

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RenderLightingCube:

Qt Code:

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void FillShape::RenderLightingCube(QGLShaderProgram* lightingShaderProgram, GLuint cubeTexture)
{
    lightingShaderProgram->setUniformValue("ambientColor", QColor(32, 32, 32));
    lightingShaderProgram->setUniformValue("diffuseColor", QColor(128, 128, 128));
    lightingShaderProgram->setUniformValue("specularColor", QColor(255, 255, 255));
    lightingShaderProgram->setUniformValue("ambientReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("diffuseReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("specularReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("shininess", (GLfloat) 100.0);
    lightingShaderProgram->setUniformValue("texture", 0);
 
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, cubeTexture);
    glActiveTexture(0);
 
    lightingShaderProgram->setAttributeArray("vertex", cubeVertices.constData());
    lightingShaderProgram->enableAttributeArray("vertex");
    lightingShaderProgram->setAttributeArray("normal", cubeNormals.constData());
    lightingShaderProgram->enableAttributeArray("normal");
    lightingShaderProgram->setAttributeArray("textureCoordinate", cubeTextureCoordinates.constData());
    lightingShaderProgram->enableAttributeArray("textureCoordinate");
 
    glDrawArrays(GL_TRIANGLES, 0, cubeVertices.size());
 
    lightingShaderProgram->disableAttributeArray("vertex");
    lightingShaderProgram->disableAttributeArray("normal");
    lightingShaderProgram->disableAttributeArray("textureCoordinate");
 
    lightingShaderProgram->release();
}

void FillShape::RenderLightingCube(QGLShaderProgram* lightingShaderProgram, GLuint cubeTexture)
{
    lightingShaderProgram->setUniformValue("ambientColor", QColor(32, 32, 32));
    lightingShaderProgram->setUniformValue("diffuseColor", QColor(128, 128, 128));
    lightingShaderProgram->setUniformValue("specularColor", QColor(255, 255, 255));
    lightingShaderProgram->setUniformValue("ambientReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("diffuseReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("specularReflection", (GLfloat) 1.0);
    lightingShaderProgram->setUniformValue("shininess", (GLfloat) 100.0);
    lightingShaderProgram->setUniformValue("texture", 0);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, cubeTexture);
    glActiveTexture(0);

    lightingShaderProgram->setAttributeArray("vertex", cubeVertices.constData());
    lightingShaderProgram->enableAttributeArray("vertex");
    lightingShaderProgram->setAttributeArray("normal", cubeNormals.constData());
    lightingShaderProgram->enableAttributeArray("normal");
    lightingShaderProgram->setAttributeArray("textureCoordinate", cubeTextureCoordinates.constData());
    lightingShaderProgram->enableAttributeArray("textureCoordinate");

    glDrawArrays(GL_TRIANGLES, 0, cubeVertices.size());

    lightingShaderProgram->disableAttributeArray("vertex");
    lightingShaderProgram->disableAttributeArray("normal");
    lightingShaderProgram->disableAttributeArray("textureCoordinate");

    lightingShaderProgram->release();
}

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**stereoMatching** · 26th June 2013, 11:34

can't you test your fbo instructions separately in another program?

Sorry but I don't get it, do you mean test it with different shader codes?

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