Hey,

I am wondering what is the proper way to implement offscreen "offline" rendering with QGLWidget. By "offline", I mean without displaying any GUI. The "online" mode works well,here is the code of the offscreen render method:

Qt Code: 
  1. ///////////////////////////////
  2. // Render the scene into a png
  3. ///////////////////////////////
  4. void GlView::renderOffScreen()
  5. {
  6.  
  7.     // We need to have a valid openGL context
  8.     makeCurrent();
  9.  
  10.     QGLFramebufferObject * fb = new QGLFramebufferObject(8000,1000, GL_TEXTURE_2D);
  11.  
  12.     // bind it and let's start drawing on it....
  13.     fb->bind();
  14.  
  15.         glClear(GL_COLOR_BUFFER_BIT |GL_DEPTH_BUFFER_BIT);
  16.  
  17.         // this must be the same size as the FrameBuffer....
  18.         glViewport(0, 0, 8000, 1000);
  19.  
  20.         glMatrixMode(GL_PROJECTION);
  21.             glLoadIdentity();
  22.  
  23.             gluOrtho2D(camera->left(),
  24.                        camera->right(),
  25.                        camera->bottom(),
  26.                        camera->top());
  27.  
  28.         glMatrixMode(GL_MODELVIEW);
  29.             glLoadIdentity();
  30.  
  31.         // renderData........
  32.         renderData();
  33.  
  34.     fb->release();
  35.  
  36.     // reset the viewport to its normal self :)
  37.     glViewport(0, 0, viewport[2], viewport[3]);
  38.  
  39.     // get the fb into a QImage
  40.     QImage tempImage = fb->toImage();
  41.  
  42.     // Delete the FB
  43.     delete fb;
  44.  
  45.     // Save the image
  46.     if ( !tempImage.save( "hello.png", "PNG") )
  47.          return;
  48.  
  49. }
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To have the "offline" version, I simply deleted the call to show on the main widget...
It works on Linux (even though you clearly the something is created then deleted), but not on win32.... so I wonder if there is a more proper solution to this.....

Thanks