Manipulating gl_LightSource[gl_MaxLights]

The The OpenGL ® Shading Language Spec version 1.20 shows the following:

struct gl_LightSourceParameters {
    vec4  ambient;             // Acli
    vec4  diffuse;             // Dcli
    vec4  specular;            // Scli
    vec4  position;            // Ppli
    vec4  halfVector;          // Derived: Hi
    vec3  spotDirection;       // Sdli
    float spotExponent;        // Srli
    float spotCutoff;          // Crli
                               // (range: [0.0,90.0], 180.0)
    float spotCosCutoff;       // Derived: cos(Crli)
                               // (range: [1.0,0.0],-1.0)
    float constantAttenuation; // K0
    float linearAttenuation;   // K1
    float quadraticAttenuation;// K2
uniform gl_LightSourceParameters  gl_LightSource[gl_MaxLights];

Also, shows the following code snippets:

lightDir = normalize(vec3(gl_LightSource[0].position)); shows many uniform* functions but nothing seems to deal with an array of uniform variable like gl_LightSource[0].

How do we set the gl_LightSource[0] fields in JavaScript? For example, (gl_LightSource[0].position

Thanks in advance for your help.

Hi pion,

WebGL is based on OpenGL ES 2.0 – that is, the version of OpenGL designed for restricted hardware like cellphones – and doesn’t support lighting out of the box; you have to code it yourself. The version of the spec you’re looking at and the lighthouse3d example are for the full desktop OpenGL, which has more features.

I think you’ve already seen the tutorials I’ve been putting together (or someone else called pion has :wink: but if you take a look at lessons 7 and 12 you’ll probably get some useful pointers.


To be honest - even in desktop OpenGL, you’re better off ignoring all of those built-in variables. They are just an ugly transition mechanism for people edging gradually from fixed-function pipelines to full-on shader rendering. You might as well pick your own uniforms, name them what you want - and optimize your lighting to do exactly what you need.

But, indeed, in OpenGL-ES 2.x and WebGL, those variables are gone.