Here is my first draft on real time stroke based rendering : NPR Gallery
I have some problems with implementation, as the whole stuff is done in software.
First pass render the scene in 160*120, glReadPixel it and then process this buffer (gradient and box filter). Tangent to the gradient gives the orientation of the stroke. But … it seems like I process the buffer before the glReadPixel has finished its work. So I tried glFinish() and glFlush() all around, but it had no impact. The weird behaviour is that you see the gradient buffer refining itself over time.
Secondly, I’d like to hardware accelerate this stuff. Any suggestions ? The first problem will come with the box filter that needs multiple iterations until all 0-length vectors are overwritten.
Credits goes to Karl-Anders Johansson from the yodel team. This is a pale copy of their demo “32 degrees in the shade”.
Suggestions and critics and flames welcome.
SeskaPeel.