Hi Glenn et. al. Today I've been revisiting the osgTerrain::DisplacementMappingTechnique, GeometryPool and associated shaders to make better use of the new #pragma(tic) shader composition. I haven't completed this work yet, but attached are the two main shaders I'm working on, these are where the bulk of the different options are for handling different numbers of colour layers, optional height fields etc. are. I have been able to replace combine two original vertex main shaders into one, and four different fragment main shaders into one. I have attached the shaders to illustrate my work in progress.
Previously the GeometryPool had to manage the selection between the different combinations of shaders and create a different osg::Program for each combination, while now I will be able to remove all this C++ code for management of shaders and replace with simply StateSet::setDefine(..) to toggle the various features on/off. This toggle on/off of features can be generic - just needing to know the name of the feature to toggle, it won't need to know about GeometryPool or where it's attached different Programs. This is big advantage as it decouples the C++ implementation details from the interface. The C++ implementation is also simpler so will be easier to understand and maintain going forward. Once I've got the DisplacementMapping/GeometryPool code sorted (hopefully by end of tomorrow) I'll check it all in and provide others a more complex illustration of how to use the new form shader composition. The work I did on osgVolume in 2013/14 managed it's own local management of different shader combinations - osg::ShaderComposition just didn't fit the problem I was trying to solve so ended up creating a local code to solve the problem. However, this work would be an ideal candidate for converting to use #pragma(tic) shader composition, implementing it should be able to remove C++ code and make the shaders easier to manage. Once I've done this it should also be an example that members of the community can use as inspiration. A note for Glenn, could you give me an example of what type of modifications to the attached shaders you'd like to add in - just sticking the GLSL code you want to add directly into the GLSL without any of the #ifdef etc. would be fine. Knowing what type of GLSL you want to inject will help me know what entry points would be useful to add to the shaders to give you the ability to customize them. Cheers, Robert.
terrain_displacement_mapping.vert
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terrain_displacement_mapping_CCC.frag
Description: Binary data
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