JarCastingglsl-specular-cook-torrance
Computes the specular power in the Cook-Torrance model.
Example
#pragma glslify: cookTorranceSpec = require(glsl-specular-cook-torrance)
uniform vec3 eyePosition;
uniform vec3 lightPosition;
uniform float roughness, fresnel;
varying vec3 surfacePosition, surfaceNormal;
void main() {
//Light and view geometry
vec3 viewDirection = normalize(eyePosition - surfacePosition);
vec3 lightDirection = normalize(lightPosition - surfacePosition);
//Surface properties
vec3 normal = normalize(surfaceNormal);
//Compute specular power
float power = cookTorranceSpec(
lightDirection,
viewDirection,
normal,
roughness,
fresnel);
gl_FragColor = vec4(power,power,power,1.0);
}
Usage
Install with npm:
npm install glsl-specular-cook-torrance
Then use with glslify.
API
#pragma glslify: cookTorrance = require(glsl-specular-cook-torrance)
float cookTorrance(vec3 lightDir, vec3 eyeDir, vec3 normal, float roughness, float fresnel)
Computes the specular power in the Cook-Torrance
lightDiris a unit lengthvec3pointing from the surface point toward the lighteyeDiris a unit lengthvec3pointing from the surface point toward the cameranormalis the unit length surface normal at the sample pointroughnessis the surface roughness parameter, between 0 and 1. 0 means surface is perfectly smooth, 1 means surface is mattefresnelthe Fresnel exponent. 0 = no Fresnel, higher values create a rim effect around objects
Returns A float representing the specular power
Note Unlike the usual Cook-Torrance model, the light power is not scaled by 1/(normal . lightDirection). This avoids an unnecessary numerically unstable division, but requires modifying how diffuse light is calculated.
License
(c) 2014 Mikola Lysenko. MIT License
