glsl-light-attenuation

GLSL function for computing light attenuation. Designed for use as a shader component with glslify and glsl-light.

install

To make avaialble in your project

npm install glsl-light-attenuation --save

example

Define a light in your shader

pragma glslify: Light = require('glsl-light')
uniform Light light;

Then use this function alongside glsl-light-direction to compute attenuation

pragma glslify: attenuation = require('glsl-light-attenuation')
pragma glslify: direction = require('glsl-light-direction')

vec3 dir = direction(light, position);
float attn = attenuation(light, dir);

algorithm

Attenuation is computed treating the light as either point or directional depending on its properties. For a good overview, see this tutorial.

The primary parameter of the light is the position, a vec4 in homogenous coordinates. The fourth element determines whether the light is directional or not.

• If the fourth element is 0.0, it will produce directional light, and attenuation is 1.0.
• If the fourth element is 1.0, it will be treated as a point light source, and attenuation will falloff as governed by the radius parameter, with the function pow(clamp(1.0 - distance / radius, 0.0, 1.0), 2.0).

API

attenuation(light, direction)

Parameters

• light : struct instance of glsl-scene-light
• direction : vec3 direction of the light

Returns

• float the computed color intensity for the material