osgShadow

The osgShadow NodeKit is now underway and will be integrated into core OpenSceneGraph and all going well will be part of the next release - OpenSceneGraph-1.3. We don't have a release date for this release, so if your impatient, check up on progress by sending a querry to the osg-users mailing list. The code will first be available in the CVS version of the OpenSceneGraph.

Deliverables for the first release of osgShadow are:

MUST HAVE

• NodeKit containing nodes and helper classes for specify: - light sources - the parts of the scene being shadowed - the parts of the scene which cast shadows - a mechansim for specifying the shadow techniques/implementations - a mechansim for specifying the options required to configure the different shadow techniques
• Shadow techniques: - stencil volume shadows

Could have

• Shadow techniques: - shadow textures - shadow maps - parallel split shadow maps

Existing implementations that can be used as source material

Stencil Shadow Volumes implementations:

• ChangzhiLi's osgShadow implementation
• Shi Jazheng and Anders Backman´s (VRlab) Shadow Volume Thesis and osgShadowVolume implementation

Parallel Split Shadow Map implementations:

• Terry Welsh's Parallel Split Shadow Map implementation
• Adrian Egli's Parallel Split Shadow Map implementation

Simple Depth Shadow implementations:

• osgdepthshadow from OpenSceneGraph/examples/osgdepthshadow
• Mihai Radu's version of the above, separated in classes and added a small scene manager [[Attach:depthShadow.zip implementation]

Online resource that are a good source of information about the various shadow techniques

• GameDev Parallel-Split Shadow Maps demo
• The Theory of Stencil Shadow Volumes (GameDev)
• An Introduction to Stencil Shadow Volumes (DevMaster)
• Practical and Robust Shadow Volumes (Nvidia)
• Fase Shadow Volumes (NVidia)
• Shadow volume (Wikipedia)
• ZP+: correct Z-pass stencil shadows
• Accelerated Stencil Shadow Extrusion via Vertex Blending (flipcode)
  - note Shi Jazheng's work above suggest that GPU compute of the shadow volume is slower than CPU..

Recent mailing list threads on shadows

• Terry Welsh - osg-users Parallel-Split Shadow Map with osg PSSM
• Terry Welsh - osg-users Parallel-Split Shadow Map with osg PSSM
• Adrian Egli - osg-users Parallel-Split Shadow Map with osg PSSM