Am 14.01.2014 19:14, schrieb Daniel Schmid:
Hello Daniel,
Usually post-perspective simply means, that coordinates are already
normalized and perspective devision was applied.
So if the light view-matrix will bring you into Lightspace / lights view
space. Multiplying this with the lights projection matrix will bring you
into clip space. Which effectively is post-perspective if I'm not mistaken.
Generally in shadow mapping the approach is always the same: Calculate a
frustum, choose some projection for the shadow caster pass. Use the
Inverse of those matrices to perspectively map the resulting depth
buffer to cameras eye space.
Without digging deeper into the specialized shadow mapping techniques:
Usually they modify the matrix in the first pass to fit most into the
shadow map precision-wise. One could say they are simply choosing some
arbitrary projections/transformations and biasing. These matrices are
the usually inverted and passed to the shadow mapping pass to bring them
into camera eyespace or clipspace again.
So effectively using those shadow mapping techniques will reduce aliasing.
Maybe you can elaborate on what you are trying to accomplish a bit more,
so we can give you better answers.
Usually when I have to deal with this kind of transformation/projection
I try to implement in glsl, as I simply don't like TexGen etc.
Hope that helps.
Is there nobody who has knowledge of how to implement post perspective texture
matrix, like used in perspective shadow map (PSM) ?
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=57877#57877
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