surface-shader.glsl

To create a shader resource that can be used in Substance 3D Painter, just create a glsl file containing a single function called shade with the following profile:

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void shade(V2F inputs);
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void shade(V2F inputs);

V2F input type definition:

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struct V2F {
   vec3 normal;               // interpolated normal
   vec3 tangent;              // interpolated tangent
   vec3 bitangent;            // interpolated bitangent
   vec3 position;             // interpolated position
   vec4 color[1];             // interpolated vertex colors (color0)
   vec2 tex_coord;            // interpolated texture coordinates (uv0)
   SparseCoord sparse_coord;  // interpolated sparse texture coordinates used by textureSparse() sampling function
   vec2 multi_tex_coord[8];   // interpolated texture coordinates (uv0-uv7)
 };
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struct V2F {
   vec3 normal;               // interpolated normal
   vec3 tangent;              // interpolated tangent
   vec3 bitangent;            // interpolated bitangent
   vec3 position;             // interpolated position
   vec4 color[1];             // interpolated vertex colors (color0)
   vec2 tex_coord;            // interpolated texture coordinates (uv0)
   SparseCoord sparse_coord;  // interpolated sparse texture coordinates used by textureSparse() sampling function
   vec2 multi_tex_coord[8];   // interpolated texture coordinates (uv0-uv7)
 };

Note: To obtain a SparseCoord for uv1-uv7, you have to explicitly call getSparseCoord(vec2) defined in lib-sparse.glsl

Surface shader outputs:

The following functions can be called from within the shade function to describe fragment properties:

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// fragment opacity. default value: 1.0
 void alphaOutput(float);
 // Second RGBA output (dual blending), only used with *add_multiply* blending mode. default value: vec4(1.0)
 void color1Output(vec4);
 // diffuse lighting contribution. default value: vec3(0.0)
 void diffuseShadingOutput(vec3);
 // specular lighting contribution. default value: vec3(0.0)
 void specularShadingOutput(vec3);
 // color emitted by the fragment. default value: vec3(0.0)
 void emissiveColorOutput(vec3);
 // fragment color. default value: vec3(1.0)
 void albedoOutput(vec3);
 // subsurface scattering properties, see lib-sss.glsl for details. default value: vec4(0.0)
 void sssCoefficientsOutput(vec4);
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// fragment opacity. default value: 1.0
 void alphaOutput(float);
 // Second RGBA output (dual blending), only used with *add_multiply* blending mode. default value: vec4(1.0)
 void color1Output(vec4);
 // diffuse lighting contribution. default value: vec3(0.0)
 void diffuseShadingOutput(vec3);
 // specular lighting contribution. default value: vec3(0.0)
 void specularShadingOutput(vec3);
 // color emitted by the fragment. default value: vec3(0.0)
 void emissiveColorOutput(vec3);
 // fragment color. default value: vec3(1.0)
 void albedoOutput(vec3);
 // subsurface scattering properties, see lib-sss.glsl for details. default value: vec4(0.0)
 void sssCoefficientsOutput(vec4);

As an example, the most basic rendering equation for computing the fragment color is: emissiveColor + albedo * diffuseShading + specularShading

Last updated 10/3/2024

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