QGLBuffer::PixelUnpackBuffer

[mikecarlos]

Hi,
Is there any one having experience on Pixelunpackbuffers. There is too little info on the web about it. THe code below results in NULL for variable ptr. Any ideas why?

regards

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bool success = mPixelBuffer->create();
mPixelBuffer->allocate(sizeof(imageData));
mPixelBuffer->setUsagePattern(QGLBuffer::DynamicDraw);
mPixelBuffer->bind();
GLubyte ptr =(GLubyte)mPixelBuffer->map(QGLBuffer::ReadWrite);
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