Minmin Gong

- [ ] Switch to GGX - [ ] Shininess to roughness conversion - [ ] Packed metallic roughness texture as in GLTF

Ray tracing GI

1

Take DXR to implement GI effects

Try to use imgui (https://github.com/ocornut/imgui) to replace the in-engine ui system.

A text table to lookup same message in different languages.

(Migrated from [wishlist](http://klayge.org/wiki/index.php/Wishlist)) Requested by cin. Add support physics engine (PhysX, Newton, Bullet, Tokamak, ODE)

Implements checkerboard rendering, similar to PS4's, in deferred rendering layer. References: http://gamingbolt.com/sony-explains-how-checkerboard-rendering-works-on-the-ps4-pro https://www.gdcvault.com/play/1022990/Rendering-Rainbow-Six-Siege http://advances.realtimerendering.com/s2017/DecimaSiggraph2017-final.pptx

Use OpenXR (https://www.khronos.org/openxr) to handle VR and AR devices.

Compile HLSLs to D3D11/D3D12/OGL/OGLES/... shaders Related to #113

Instead of direct rendering, Renderable::Render() can return a command buffer, and submit command buffer later.

Dynamic scaling dependents on previous frame rate Dependence on #49