[osg-users] Get current Billboard ModelView matrix?

[Philipp Meyer]

Hi,

that was my first idea as well, however, then I realized that this approach does not work.

The problem is that there is no way to know if a certain pixel still shows the same fragment. For example, if the camera view angle changes by 180 degrees in one frame, the pixel at the 0,0 texture coordinate would no longer refer to the same fragment. Therefore, the program would compute the delta between two unrelated fragments, yielding a wrong result.

However, with my approach, the program would calculate the old fragment position by using the old view matrix (pre 180 degree change) and the model matrix (unchanged in this example), compute the distance to the camera and compare it to the old distance, resulting in 0. 

Thank you!

Cheers,
Philipp

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http://forum.openscenegraph.org/viewtopic.php?p=67929#67929