[Terrain] Create Terrain Rendering Path

[ChaoSXDemon]

Currently we do not have a way to render terrain other than a demo one. This task captures all the effort to bring Terrain related rendering to this engine.

[T-rvw]

Hi, @ChaoSXDemon . There is an example project applied by bgfx. You can find it under ThirdParty/bgfx/examples/example27-terrain in CatDogEngine.sln. Just set it as startup project to run the demo.
It is also recommended to run other examples to be familiar with bgfx at first :)

[T-rvw]

• Terrain texturing
  • RasterTek has a basic tutorial : https://www.rastertek.com/dx11ter03.html , search TerrainClass::BuildTerrainModel in the website. The basic idea is just to treat mesh as triangles to set uv. And the final visual result depends on the actual texture size and texture tiling mode.
  • Advanced texture tiling mode : bgfx has a new example-49 about hex tiling to reduce the feeling of duplication.

[T-rvw]

• Terrain geometry
  • Not useful now. But looks interesting. GPU Gems 3 - Procedural terrain at runtime. https://developer.nvidia.com/gpugems/gpugems3/part-i-geometry/chapter-1-generating-complex-procedural-terrains-using-gpu
  • GPU Pro6 - Dynamic GPU Terrain

[T-rvw]

• Terrain rendering
  • GPU Gems 2 - gpu clipmap. https://developer.nvidia.com/gpugems/gpugems2/part-i-geometric-complexity/chapter-2-terrain-rendering-using-gpu-based-geometry
  • GPU Pro 7 - adaptive virtual texture. Another implementation different with procedural virtual texture.

[T-rvw]

• Famous Game Cases:
  • Battle Field 3 https://media.contentapi.ea.com/content/dam/eacom/frostbite/files/gdc12-terrain-in-battlefield3.pdf
  • Frostbite https://media.contentapi.ea.com/content/dam/eacom/frostbite/files/chapter5-andersson-terrain-rendering-in-frostbite.pdf

[ChaoSXDemon]

This issue is now closed as PR:
https://github.com/CatDogEngine/CatDogEngine/pull/47

has been merged. We will branch into other issues to generate different types of terrain rendering and generation.