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i'm new to OpenGL and i need to use a QGLFrameBufferObject for off-screen rendering (or solve my problem with grabFrameBuffer, see below). I read the example in Qt Documentation, but there are too many things at once, it is kind of difficult for me. Could someone explain me the different steps to use a QGLFrameBufferObject. I'd like to create a buffer and add several images inside (with setTransform() also) and then save just a part of it into a PNG image with transparency.

How to proceed ?

I've read several topic about people having trouble with different points for this kind of thing, so I guess it is gonna be tough ...

In fact i've already done all this into a QGraphicsView with a QGLWidget as Viewport, but using grabFrameBuffer to save the scene doesn't work (transparency problem and I can't use grabFrameBuffer if I want to .hide() the scene ... do I ?).

RyuKa
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  • Me again. I'm getting somewhere with `QGLFrameBufferObject`. I succeeded to render images of size 7574*2303 for example, but when i go to over around 8000*2700, i got **"Framebuffer incomplete attachment"**. So, is there a **size limit for QGLFramebufferObject** and if so, what is it ? Thank you in advance. – RyuKa Mar 01 '12 at 14:54
  • I decided to cut into several images when it's too big. Is there any faster way to the **QGLFramebufferObject content**, than `.toImage().save("name","png");` ? – RyuKa Mar 02 '12 at 14:07
  • there is a limit in the graphics card's memory. On my NVidia card the max texture dim is 8192 for example – Martin Beckett Apr 13 '12 at 23:05

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