Depth buffer and Display co-ordinates

[Damini Dey]

Hi,

    I am trying to compare the distance of a PolyData point from the
camera to the corresponding
depth buffer value. I convert the world co-ordinates of the point to
Display co-ordinates.
However, I have a problem - the depth buffer values range from 0 to 1
(they are read
from the OpenGL render window with glReadPixels) and do not match the
Display co-ordinates.

How can I convert the depth buffer values to Display co-ordinates ?  I
tried simple
scaling using the camera clipping range but it does not work correctly.
Has anyone
solved this problem before ?

Thanks,

    Damini.




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