LVutner / ClearSkyPBS

A tiny PBS implementation for S.T.A.L.K.E.R. Clear Sky

ClearSkyPBS

A tiny PBS implementation for S.T.A.L.K.E.R. Clear Sky.

Tested on latest (1.5.10) patch. Original shading is deprecated; along with texture layout.

Features

• Physically plausible GGX + Lambert model
• Filtered importance sampling for specular IBL
• Metallic - Roughness workflow

Textures

I've decided to not complicate things with textures. The format and layout is simple to understand:

Name	Red	Green	Blue	Alpha
name.dds	Albedo.r	Albedo.g	Albedo.b	Alpha
name_bump.dds	Normal.x	Normal.y	Roughness	Metalness
name_bump#.dds	Empty	Empty	Empty	Height map

Layout for detail textures is the same. Alpha became a blending factor: data = lerp(base_layer, detail_layer, detail_alpha);

You should use good DXT5 compressor, especially for _bump textures!

G-Buffer

The following G-Buffer layout is used:

Name	Red	Green	Blue	Alpha
s_position	Position.x	Position.y	Position.z	Roughness
s_normal	Normal.x	Normal.y	Normal.z	AO
s_diffuse	Albedo.r	Albedo.g	Albedo.b	Metalness

Screenshots

Requirements

• PBR textures (see "Textures" section)
• DX10 renderer
• r3_gbuffer_opt set to off (you can do it in user.ltx file, or in console)

Known issues

• Terrain shader is not converted to new texture format (To be done)

Disclaimer

• This is a project done purely for fun. It does not implement advanced rendering techniques, nor aims to be the most accurate renderer ever.
• I've tried to cut corners everywhere, just to get somewhat physically plausible shading :)
• There is no gamma correction, HDR, and proper tonemapping.
• For more informations see tinypbs.h

Credits:

- Michal Iwanicki & Angelo Pesce (DFG approximation)
- xroo (Test map where I've been testing this shader)
- Caesar (CS port of test map from xroo)
- Blazej Kozlowski (Bunny ASCII art)

References:

- https://developer.nvidia.com/gpugems/gpugems3/part-iii-rendering/chapter-20-gpu-based-importance-sampling
- http://miciwan.com/SIGGRAPH2015/course_notes_wip.pdf
- https://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
- https://schuttejoe.github.io/post/ggximportancesamplingpart1/
- https://www.unrealengine.com/en-US/blog/physically-based-shading-on-mobile