OpenGl 2d

[Lele]

Thanks for the sample code,
I think that for having a good comparision with real system it would be necessary to load a different buffer everytime, I mean not from a file but from a sample buffer just like camera acquisition, so we could also check the memory transfer rate from RAM to the board.

Anyway, I'm also looking at qpaintengine_opengl.cpp like Glitch suggested (Arthur painting system) and there the drawImage is implemented using textures and not glDrawPixels.

In conclusion, Arthur painting system could be the solution for who wants to take advantage of using harware acceleration without learning OpenGL directly, unfortunately I can't find good examples for that and the documentations is not helpful.

[firas]

I'm trying to understand the best way to do such a 2d display,
your use of glDrawPixels is interesting and very fast, and most of all doesn't need to have width and heigh power of 2.
But unfortunately it seems to work differently than other OpenGL rendering, so it's not possible to zoom or resize like when using Texture.

actually it is possible to use the zoom capability. check the QT documentation:

void QGLWidget::resizeGL ( int width, int height ) [virtual protected]
This virtual function is called whenever the widget has been resized. The new size is passed in width and height. Reimplement it in a subclass.
There is no need to call makeCurrent() because this has already been done when this function is called.

So now I'm using
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,
GL_RGB, GL_UNSIGNED_BYTE, data );

and it's ok even because it automatically resize the width and heigh to be power of 2, but it's very slow if you do that at every frame

re-implement resizeGL(newWidth,newHeight), and it should be ok.

So I just wanted to know if you're using drawpixel for showing a buffer without working on it (zoom, resize, overlays) or it was just a test.

thanks

there are different ways to do (zoom, resize, overlays), like some stuff could be easily done as QImage then you convert that to openGL and do some other stuff and so on..

my inetntion of the test was to find the fastest way of rendering video frames (image sequences) after processing them, e.i. to find the fastest way of displaying the images.