GLSL translation of this fake sub-surface scattering shader by InvalidPointer.
I’m always amazed when these things actually work…
Vertex Shader:
////////////////////////////
// SUB-SURFACE SCATTER VS //
////////////////////////////
/* --------------------------
SubScatter Vertex Shader:
Fake sub-surface scatter lighting shader by InvalidPointer 2008.
Found at
http://www.gamedev.net/community/forums/topic.asp?topic_id=481494
HLSL > GLSL translation
toneburst 2008
-------------------------- */
// Set light-position
uniform vec3 LightPosition;
// Varying variables to be sent to Fragment Shader
varying vec3 worldNormal, eyeVec, lightVec, vertPos, lightPos;
void subScatterVS(in vec4 ecVert)
{
lightVec = LightPosition - ecVert.xyz;
eyeVec = -ecVert.xyz;
vertPos = ecVert.xyz;
lightPos = LightPosition;
}
////////////////
// MAIN LOOP //
////////////////
void main()
{
worldNormal = gl_NormalMatrix * gl_Normal;
vec4 ecPos = gl_ModelViewProjectionMatrix * gl_Vertex;
// Call function to set varyings for subscatter FS
subScatterVS(ecPos);
//Transform vertex by modelview and projection matrices
gl_Position = ecPos;
//Forward current texture coordinates after applying texture matrix
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
}
Fragment Shader:
////////////////////////////
// SUB-SURFACE SCATTER FS //
////////////////////////////
/* --------------------------
SubScatter Fragment Shader:
Fake sub-surface scatter lighting shader by InvalidPointer 2008.
Found at
http://www.gamedev.net/community/forums/topic.asp?topic_id=481494
HLSL > GLSL translation
toneburst 2008
-------------------------- */
// Variables for lighting properties
uniform float MaterialThickness;
uniform vec3 ExtinctionCoefficient; // Will show as X Y and Z ports in QC, but actually represent RGB values.
uniform vec4 LightColor;
uniform vec4 BaseColor;
uniform vec4 SpecColor;
uniform float SpecPower;
uniform float RimScalar;
//uniform sampler2D Texture;
// Varying variables to be sent to Fragment Shader
varying vec3 worldNormal, eyeVec, lightVec, vertPos, lightPos;
float halfLambert(in vec3 vect1, in vec3 vect2)
{
float product = dot(vect1,vect2);
return product * 0.5 + 0.5;
}
float blinnPhongSpecular(in vec3 normalVec, in vec3 lightVec, in float specPower)
{
vec3 halfAngle = normalize(normalVec + lightVec);
return pow(clamp(0.0,1.0,dot(normalVec,halfAngle)),specPower);
}
// Main fake sub-surface scatter lighting function
vec4 subScatterFS()
{
float attenuation = 10.0 * (1.0 / distance(lightPos,vertPos));
vec3 eVec = normalize(eyeVec);
vec3 lVec = normalize(lightVec);
vec3 wNorm = normalize(worldNormal);
vec4 dotLN = vec4(halfLambert(lVec,wNorm) * attenuation);
//dotLN *= texture2D(Texture, gl_TexCoord[0].xy);
dotLN *= BaseColor;
vec3 indirectLightComponent = vec3(MaterialThickness * max(0.0,dot(-wNorm,lVec)));
indirectLightComponent += MaterialThickness * halfLambert(-eVec,lVec);
indirectLightComponent *= attenuation;
indirectLightComponent.r *= ExtinctionCoefficient.r;
indirectLightComponent.g *= ExtinctionCoefficient.g;
indirectLightComponent.b *= ExtinctionCoefficient.b;
vec3 rim = vec3(1.0 - max(0.0,dot(wNorm,eVec)));
rim *= rim;
rim *= max(0.0,dot(wNorm,lVec)) * SpecColor.rgb;
vec4 finalCol = dotLN + vec4(indirectLightComponent,1.0);
finalCol.rgb += (rim * RimScalar * attenuation * finalCol.a);
finalCol.rgb += vec3(blinnPhongSpecular(wNorm,lVec,SpecPower) * attenuation * SpecColor * finalCol.a * 0.05);
finalCol.rgb *= LightColor.rgb;
return finalCol;
}
////////////////
// MAIN LOOP //
////////////////
void main()
{
gl_FragColor = subScatterFS();
}
