Problem 1 :
With GLSL, multi pass to apply each shadow map is not required.
Problem 2 :
GLSL code use "shadow2DProj" build-in function to look up in shadow texture.
Projection is orthogonal so "shadow2D" build-in function is sufficient.
Problem 3:
Bad calcul in
osgShadow::ParallelSplitShadowMap::calculateLightViewProjectionFormFrustum(..)
provide some visual error in specific configuration.
to reproduce pssm_bug.jpg, you need to add a light direction in osgshadow.cpp example (done in joint osgshadow.cpp file)
then "osgshadow --noUpdate --pssm --maxFarDist 500 --minNearSplit 500 --mapcount 6 --debug-color model_test.3ds"
As you can see in pssm_bug.jpg and pssm_fix.jpg, performance is really better when Problem 1 is fixed.
"
modifications of the osgShadow header naming styles as well. The
osgDB::Serializer header is also changed to add new Vec2 serializer
macros because of the needs of osgShadow classes. It should compile
fine on both Windows and Linux. But I have only done a few tests to
generate .osgb, .osgt and .osgx formats with these new wrappers."
polygon offset complicate. so i looked for a solution to remove this offset.
i changed the shader, also the filtering (default: on) use now a correct 3x3 filter:
1 0 1
0 2 0
1 0 1
div: 6
of course a better one would be
1 2 1
2 4 2
1 2 1
div: 16
but this isn't as performant as the simple filter above is. because we need only 5 texture lookups instead of 9, and the result is still good, if you wish we can add a enum to change the pcf filter type once, if there is a need.
testet on NVidia Quatro 570M and on ATI Radeon X1600
"
unfort. i couldn't test it on any ATI system. may there will be still another problem there. if there are still some artefacts. we should try out better fZOffSet value
"
(a) some objects behind the camera can cast shadow
(b) object aboive the camera can cast shadow
then i fixed the shadow map orientation, now screen x coordinate alinged which improve the quality"
