# glsl-specular-cook-torrance Computes the specular power in the Cook-Torrance model. # Example ```glsl #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-phong ``` Then use with [glslify](https://github.com/stackgl/glslify). # API ```glsl #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 * `lightDir` is a *unit length* `vec3` pointing from the surface point toward the light * `eyeDir` is a *unit length* `vec3` pointing from the surface point toward the camera * `normal` is the *unit length* surface normal at the sample point * `roughness` is the surface roughness parameter, between 0 and 1. 0 means surface is perfectly smooth, 1 means surface is matte * `fresnel` the 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