Results 1 to 5 of 5

Thread: Do offscreen render(openGL) with Qt5

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. 25th June 2013, 05:54 #1
    saman_artorious's Avatar
    saman_artorious
    saman_artorious is offline Advanced user
    Join Date
    Feb 2012
    Location
    Armenia/Yerevan
    Posts
    400
    Thanks
    15
    Thanked 16 Times in 15 Posts
    Qt products
    Qt4 Qt5
    Platforms
    Unix/X11

    Default Re: Do offscreen render(openGL) with Qt5

    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: 
    1. void GlWidget::paintGL()
    2. {
    3.     BakeDynamicTexture();
    4.  
    5. //    RenderShapes();
    6.  
    7.     glClearColor(0, 0, 0.0f, 1.0f);
    8.     //    //! [2]
    9.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    10.     glViewport(0, 0, width(),height());
    11.  
    12.     QMatrix4x4 mMatrix;
    13.     QMatrix4x4 vMatrix;
    14.  
    15.     QMatrix4x4 cameraTransformation;
    16.     cameraTransformation.rotate(alpha, 0, 1, 0);
    17.     cameraTransformation.rotate(beta, 1, 0, 0);
    18.  
    19.     QVector3D cameraPosition = cameraTransformation * QVector3D(0, 0, distance);
    20.     QVector3D cameraUpDirection = cameraTransformation * QVector3D(0, 1, 0);
    21.     vMatrix.lookAt(cameraPosition, QVector3D(0, 0, 0), cameraUpDirection);
    22.  
    23.     QMatrix4x4 mvMatrix;
    24.     mMatrix.setToIdentity();
    25.  
    26.     mvMatrix = vMatrix * mMatrix;
    27.  
    28.     QMatrix3x3 normalMatrix;
    29.     normalMatrix = mvMatrix.normalMatrix();
    30.  
    31.     QMatrix4x4 lightTransformation;
    32.     lightTransformation.rotate(lightAngle, 0, 1, 0);
    33.  
    34.     QVector3D lightPosition = lightTransformation * QVector3D(0, 1, 1);
    35.  
    36.     //! [3]
    37.     //##########################
    38.     //    lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
    39.     //    shpFill->RenderCube       (&lightingShaderProgram, dynamicTexture);
    40.     //    lightingShaderProgram.release();
    41.     //##########################
    42.  
    43.     //! [5]
    44.     lightingShaderProgram.bind();
    45.  
    46.     lightingShaderProgram.setUniformValue("mvpMatrix", pMatrix * mvMatrix);
    47.     lightingShaderProgram.setUniformValue("mvMatrix", mvMatrix);
    48.     lightingShaderProgram.setUniformValue("normalMatrix", normalMatrix);
    49.     lightingShaderProgram.setUniformValue("lightPosition", vMatrix * lightPosition);
    50.  
    51.     shpFill->RenderLightingCube(&lightingShaderProgram, dynamicTexture);
    52.  
    53.     mMatrix.setToIdentity();
    54.     mMatrix.translate(lightPosition);
    55.     mMatrix.rotate(lightAngle, 0, 1, 0);
    56.     mMatrix.rotate(45, 1, 0, 0);
    57.     mMatrix.scale(0.1);
    58.  
    59.     coloringShaderProgram.bind();
    60.     coloringShaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix);
    61.  
    62.     shpFill->colorLightingCube(&coloringShaderProgram);
    63. }
    To copy to clipboard, switch view to plain text mode 


    Baking part:
    Qt Code: 
    1. void GlWidget::BakeDynamicTexture()
    2. {
    3.     fbo->bind();
    4.  
    5.     RenderShapes();
    6.  
    7.     fbo->release();
    8.  
    9.     dynamicTexture = fbo->texture();
    10. }
    To copy to clipboard, switch view to plain text mode 

    RenderShapes (instead of drawing a shape file here, simply draw something else, check if it draws successfully)
    Qt Code: 
    1. void GlWidget::RenderShapes()
    2. {
    3.     QMatrix4x4 sMatrix;
    4.  
    5.     glClearColor(0.1f, 0.5f, 0.0f, 1.0f);
    6.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    7.     glViewport(0, 0, 256,256);
    8.  
    9.     shaderProgram.bind();
    10.  
    11.     sMatrix.setToIdentity();
    12.  
    13.     shaderProgram.setUniformValue("mvpMatrix", sMatrix);
    14.  
    15.     shpFill->Render(&shaderProgram);
    16.  
    17.     shaderProgram.release();
    18. }
    To copy to clipboard, switch view to plain text mode 

    RenderLightingCube:
    Qt Code: 
    1. void FillShape::RenderLightingCube(QGLShaderProgram* lightingShaderProgram, GLuint cubeTexture)
    2. {
    3.     lightingShaderProgram->setUniformValue("ambientColor", QColor(32, 32, 32));
    4.     lightingShaderProgram->setUniformValue("diffuseColor", QColor(128, 128, 128));
    5.     lightingShaderProgram->setUniformValue("specularColor", QColor(255, 255, 255));
    6.     lightingShaderProgram->setUniformValue("ambientReflection", (GLfloat) 1.0);
    7.     lightingShaderProgram->setUniformValue("diffuseReflection", (GLfloat) 1.0);
    8.     lightingShaderProgram->setUniformValue("specularReflection", (GLfloat) 1.0);
    9.     lightingShaderProgram->setUniformValue("shininess", (GLfloat) 100.0);
    10.     lightingShaderProgram->setUniformValue("texture", 0);
    11.  
    12.     glActiveTexture(GL_TEXTURE0);
    13.     glBindTexture(GL_TEXTURE_2D, cubeTexture);
    14.     glActiveTexture(0);
    15.  
    16.     lightingShaderProgram->setAttributeArray("vertex", cubeVertices.constData());
    17.     lightingShaderProgram->enableAttributeArray("vertex");
    18.     lightingShaderProgram->setAttributeArray("normal", cubeNormals.constData());
    19.     lightingShaderProgram->enableAttributeArray("normal");
    20.     lightingShaderProgram->setAttributeArray("textureCoordinate", cubeTextureCoordinates.constData());
    21.     lightingShaderProgram->enableAttributeArray("textureCoordinate");
    22.  
    23.     glDrawArrays(GL_TRIANGLES, 0, cubeVertices.size());
    24.  
    25.     lightingShaderProgram->disableAttributeArray("vertex");
    26.     lightingShaderProgram->disableAttributeArray("normal");
    27.     lightingShaderProgram->disableAttributeArray("textureCoordinate");
    28.  
    29.     lightingShaderProgram->release();
    30. }
    To copy to clipboard, switch view to plain text mode 
    Reply With Quote Reply With Quote

  2. The following user says thank you to saman_artorious for this useful post:

    stereoMatching (25th June 2013)
  3. 26th June 2013, 11:34 #2
    stereoMatching
    stereoMatching is offline Intermediate user
    Join Date
    Jan 2011
    Posts
    127
    Thanks
    42
    Thanked 4 Times in 4 Posts
    Qt products
    Qt4
    Platforms
    Windows

    Default Re: Do offscreen render(openGL) with Qt5

    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?
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Similar Threads

  1. Render image on QLabel using openGl
    By vinodpaul in forum Newbie
    Replies: 2
    Last Post: 14th August 2012, 17:57
  2. QGLWidget render or QGraphicsView with GL viewport render
    By QTInfinity in forum Qt Programming
    Replies: 2
    Last Post: 28th November 2011, 11:34
  3. OpenGL render to texture
    By Nicuvëo in forum Qt Programming
    Replies: 2
    Last Post: 26th March 2011, 12:07
  4. OpenGL Render issue when using QGLWidget with QGraphicsView
    By outburstx in forum Qt Programming
    Replies: 1
    Last Post: 7th May 2010, 17:20
  5. Drawing to an offscreen buffer
    By Dutch112 in forum Qt Programming
    Replies: 5
    Last Post: 6th May 2009, 16:49

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules

Qt is a trademark of The Qt Company.