A generic OSGB loader for VSG and more

[xarray]

I am very pleased to tell you that a lightweight OSGB format reading project is initially implemented and managed at https://gitee.com/xarray/generic-osgb.
The core part DOES NOT depend on OSG or any other thirdparty libraries, and only requires the C++ standard library. At present, integration examples with VSG has already been implemented, and I have initially tested the reading of general OSGB/OSGT models and oblique photography data (the latter requires the vsg_plugin_integration example).

This project will continue to be updated. The next step in the plan is to support Web 3D engines in loading OSGB data through WASM, as well as examples for Unity and Unreal. I look forward to your help in finding issues and submitting code, and to using it in your commercial and open-source projects.

[robertosfield]

Congrats @xarray, looks like an awesome library and capability. I'm just back from a trip so haven't had a chance to review code yet other like follow the link to the repo.

I'm thinking this would be useful dependency for vsgXchange to link to rather than osg2vsg which is well out of date now. Thoughts?

You mention phong shaders, how did you go about creating and managing the shaders?

Since the introduction of vsg::ShaderSet I've planned rewriting osg2vsg to use a ShaderSet for it, and have one or more uber shaders that are specialized by #define to provide the equivalent to OpenGL modes. I still think this approach has merit, and potentially having such a OSG/OpenGL specific ShaderSet could be a nice addition to the VSG built-in ShaderSets.

Seems like potential for merging/adding to the VSG and vsgXchange to facilitate generic-osgb integration. Thoughts?

[xarray]

I can also incorporate the deprecated osgwrappers into the generic-osgb project, so that it will subsequently have the ability to convert .osg format as well. This project is entirely under the MIT license, so I'm fine with either having vsgXchange depend on it or merging it directly. Of course, since it has a large number of serializer files built in, I think it's better to keep it relatively independent; I'll sync a copy to GitHub in the next couple of days.

The current material and shader setup is still very primitive—it can only use 2D textures from texture unit 0, and by default only one VsgSceneBuilder::_shaderSet is created; see https://gitee.com/xarray/generic-osgb/blob/master/examples/vsg_scene_builder.h. I think an uber shader set is definitely necessary, mainly to accommodate multiple texture units and non-2D textures. Many other fixed-pipeline features also can't be converted for now; I've listed them all in the comments at the top of vsg_scene_builder.h—see "osg classes that are NOT converted."