"Soft shadow mapping is basically the same as hard shadow mapping beside that
it uses a different fragment shader.
So for me it makes sense that osgShadow::SoftShadowMap is derived from
osgShadow::ShadowMap, this makes it easier to maintain the two classes.
Additional SoftShadowMap also provides the same Debug methods as ShadowMap."
- set the resolution of the shadow map; it calls dirty() to
re-initialize at next update
- keep a list of Shader objects to use instead of the default ones, if
the list is empty, the default shaders are used
- explicitly create the Uniform variables, so that subsequent additions
that require more Uniforms can put them in a central place
- set a Light or LightSource to use explicitly for shadow casting,
allows multiple lights in the scene, with one casting shadows
There are two additions that do not ( yet ) function correctly, but in
the present usage they do not interfere with the regular usage of the
techique:
- support for using spotlights, it's using Light.spotCutoff to determine
if it's a spot-light and not point-light,
there is an error in the setup of either the shadow camera or the
texgen, most likely due to the direction of the spotlight, since the
position is being used just like in point or directional lights.
- creation of a debugHUD
the hud is created properly, ( the example included shows it ), but
it displays only white, there has been some discussion of displaying the
shadow map, but I could not find it, the addition of a simple fragment
shader with the appropriate color transform should get this going."
(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"
"I have adapted to osgShadow the soft shadow map technique described in "Efficient Soft-Edged Shadows Using Pixel Shader Branching" by Yury Uralsky, Chapter 17 of GPU Gems 2 (Matt Pharr ed. Addison-Wesley).
Here is my code in attachment: basically, it works in the same way as osgShadow/ShadowMap (core code is copied from it) but implements a specific GLSL shader for the soft rendering of penumbra.
I have tested it under Linux with a NVidia graphic card, but there should be no dependency on platform nor on the graphics driver (as far as they support GLSL 2). Screenshots attached show the current results (frame rate bound to v-sync, but the shader takes actually not much time)."
