"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."
I think I may have discovered a bug in osgShadow/ShadowMap.cpp that results in incomplete shadows being generated.
The problem seems to caused by an incorrect interpretation of the spot light cutoff angle. The valid ranges for spot cutoff are 0-90 and 180, i.e half the 'field of view' for the spotlight. Whereas the shadow map code seems to assume the the spot cutoff is equal to the field of view. This results in the shadows generated by the spotlight getting clipped at half the spot cutoff angle.
I have fixed this in my copy of ShadowMap.cpp:
===============================
//Original code from OSG 2.6:
if(selectLight->getSpotCutoff() < 180.0f) // spotlight, then we don't need the bounding box
{
osg::Vec3 position(lightpos.x(), lightpos.y(), lightpos.z());
float spotAngle = selectLight->getSpotCutoff();
_camera->setProjectionMatrixAsPerspective(spotAngle, 1.0, 0.1, 1000.0);
_camera->setViewMatrixAsLookAt(position,position+lightDir,osg::Vec3(0.0f,1.0f,0.0f));
}
===============================
// My modifications:
float fov = selectLight->getSpotCutoff() * 2;
if(fov < 180.0f) // spotlight, then we don't need the bounding box
{
osg::Vec3 position(lightpos.x(), lightpos.y(), lightpos.z());
_camera->setProjectionMatrixAsPerspective(fov, 1.0, 0.1, 1000.0);
_camera->setViewMatrixAsLookAt(position,position+lightDir,osg::Vec3(0.0f,1.0f,0.0f));
}
This change seems correct for spot cutoff in the range 0, 90, but since OpenGL doesn't claim to support cutoffs >90 && <180, I'm not sure how shadow map should deal with those cases, but ignoring spot cut off greater than 90 here seems reasonable to me.
"
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
"
1:
Shadow map camera sets ABSOLUTE_RF_INHERIT_VIEWPOINT refernce frame.
2:
Light Direction by matrix multiplications replaced with transform3x3 multiplication.
3:
I made DebugingHUD functional by adding special draw callback. Former version was simply drawing pale square.
4:
I was tempted to make 4 th change but decided to not do it. Instead I put it whith #if VIEW_DEPNDENT_TEXGEN. If you decide you may let it go.
When objects are not centered at 0,0,0 coord but in some distant location (for example at surface of earth ellipsoid) shadow texgen suffers from inadequate precision of float matrices. I changed that by premultiplying Texgen matrix (using OSG double matrices) with inverse modelview and applying it later with ModelView identity matrix. This tweak may be appropriate for OverlayNode texgen as well.
I left former version because I suspect that this change will make osgShadow::ShadowMap view dependant. Currently texgen matrix remains the same no matter what View displays it. With my change it wuld be different for each view. This touches the subject of View Dependent Shadow Techniques that J-S asked recently."
File osgShadow/Version.cpp, Line 25:
const char* osgShaodowGetLibraryName()
should be:
const char* osgShadowGetLibraryName()
File CMakeModules/OsgMacroUtils.cmake, Line 224:
SET_TARGET_PROPERTIES(${TARGET_TARGETNAME} PROPERTIES DEBUG_POSTFIX ${CMAKE_DEBUG_POSTFIX})
should be:
SET_TARGET_PROPERTIES(${TARGET_TARGETNAME} PROPERTIES DEBUG_POSTFIX "${CMAKE_DEBUG_POSTFIX}")
Otherwise setting CMAKE_DEBUG_POSTFIX to an empty string instead of "d" in
the main CMakeLists.txt does not work under Linux.
"
with the shader for textured objects. This works very well in cases
where there could be a mix of textured and non-textured objects in the
scene, and it makes the initialization more robust.
The idea is from PSSM, to add a 1pixel texture to the main rendering as
to provide white for any objects missing textures."
- 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"
precise, the shader does not compile on os x because of some
type-conflicts ala "can not convert from const int to const float"
So I changed the offending lines to force the type of the vars. It works
now on OS X (albeit very slowly, 3fps on a 7300), perhaps you find the
changes useful. Note: perhaps there is a better way in shaders to
cast/convert from int to float and viceversa."
"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)."
so I' ve set up a macro that uses the variable name expanded for linking, and test if a variable ${LINK_VAR_NAME}_DEBUG
like OPENTHREADS_LIBRARY_DEBUG exists and in case uses it for linking in debug mode.
I' ve also set up FindOpenThreads to set up these variables.
I had to edit the core libraries CMakeLists to add the calls to the macros used.
I' ve tested under MSVC"
