Switch to built-in G-Buffer generator

[Looooong]

Fixes

• 25

• 21

• 17

Change

• Change from custom G-Buffer generator to Unity builtin G-Buffer generator.
• Add VXGI/Standard and VXGI/Standard (Specular setup) that mimics Unity counterparts.
• Rename G-Buffer textures to match Unity counterparts.
• Support render texture generation for Camera.depthTextureMode.
• Support PostProcessing.PostProcessDebug script to render debug overlay.
• Add options to VXGIRenderPipelineAsset to enable/disable environment lighting and environment reflection.
• Change light intensity value from gamma to linear.
• Change all render texture read/write mode to linear.
• Use ARGBHalf texture for screen buffer.

Deprecate

• Deprecate Voxel-based Shader/Basic shader. Recommend switching to VXGI/Standard and VXGI/Standard (Specular setup).

Details

Change from custom G-Buffer generator to Unity builtin G-Buffer generator

At the time of implementing deferred rendering path, I didn't take account of energy conservation of light transport over metallic surface and other properties. This results in custom shader lighting properties not matching Unity counterparts. Hence, the custom material converted from the one using Standard Shader or the one from Unity Asset Store doesn't look identical and often look unrealistic. This change uses Unity builtin shader pass to generate G-Buffers.

Side effects:

• The 4th G-Buffer used to only contain emission value, now can also contain environment lighting (must be enabled on render pipeline asset), which can be configured in Lighting Setting.
• Enable parallax map and details map.

Rename G-Buffer textures to match Unity counterparts

This allow other image effect libraries, such as Post Processing, to make use of G-Buffer textures.

Support depth texture generation for Camera.depthTextureMode

Also supports image effect libraries. Currently supports DepthTextureMode.Depth (_CameraDepthTexture - always generated) and DepthTextureMode.DepthNormals (_CameraDepthNormalsTexture)

Add VXGI/Standard and VXGI/Standard (Specular setup) that mimics Unity counterparts

With the use of builtin Unity shader for G-Buffer generation, VXGI/Standard and VXGI/Standard (Specular setup) shader are introduced to mimics Unity counterparts. This deprecates Voxel-based Shader/Basic shader.

Support PostProcessing.PostProcessDebug script to render debug overlay

As the title says.

Add options to VXGIRenderPipelineAsset to enable/disable environment lighting and environment reflection

It is recommended to disable environment lighting as it is replaced by voxel-based global illumination. On the other hand, environment reflection can be enabled to reflect skybox on reflective surface.

Change light intensity value from gamma to linear

To ensure physically correct output (reference).

Change all render texture read/write mode to linear

Technical stuffs.