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Shading Model

What is a Shading Model

Shading Models determines how a surface will interact with light.

They dictate how the Material's input data is utilized to produce the final visual output.

Not only can you use one of these pre-defined shading models, but you can also create your own shading model to shade your surface the way you want.

S&box currently ships with one shading model ShadingModelStandard which should be what most people would use.

Using built-in shading models

PS { #include "common/pixel.hlsl" float4 MainPs( PixelInput i ) : SV_Target0 { Material m = Material::From( i ); /* m.Metalness = 1.0f; // Forces the object to be metalic */ return ShadingModelStandard::Shade( i, m ); } }

Creating a shading model

Structure

Light Structure

We provide the following light types to be used from shader code:

  • DynamicLight
  • StaticLight
  • EnvironmentMapLight
  • AmbientLight

All can be created with Light::From() and all but AmbientLight can be iterated with Light::Count(), Light types already handle everything from tiled rendering to shadowing seamlessly, for example:

// // Shade direct lighting for dynamic lights // for ( uint index = 0; index < DynamicLight::Count( material.ScreenPosition ); index++ ) { Light light = DynamicLight::From( material.ScreenPosition, material.WorldPosition, index ); vResult += light.Color * dot( material.Normal, light.Direction ); }

Each light structure gives you the following data to be consumed:

//----------------------------------------------------------------------------- // Light structure //----------------------------------------------------------------------------- struct Light { // The color is an RGB value in the linear sRGB color space. float3 Color; // The normalized light vector, in world space (direction from the // current fragment's position to the light). // Skipped by Ambient Light float3 Direction; // The position of the light in world space. This value is the same as // Direction for directional lights. float3 Position; // Attenuation of the light based on the distance from the current // fragment to the light in world space. This value between 0.0 and 1.0 // is computed differently for each type of light (it's always 1.0 for // directional lights). // Skipped by Ambient Light float Attenuation; // Visibility factor computed from shadow maps or other occlusion data // specific to the light being evaluated. This value is between 0.0 and // 1.0. (It's always 1.0 for ambient lights) float Visibility; };

Note that ambient lights skip some of this data.

Applying Fog

You can apply fog to shaders by using DoAtmospherics()

vColor = DoAtmospherics( material.WorldPosition, material.ScreenPosition.xy, vColor ); return vColor;

Usage

Example ShadingModel

Here's an example of doing a simple Toon shader from the structure you get from lights

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