source: java/client_3D/static/shared/res/shaders/old_diffuse_light.glsl @ 65

//name diffuse_light
//vert
varying vec3 ecPos;
varying vec3 ecNormal;                  
void main()
{       
        gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * gl_Vertex;
        gl_TexCoord[0].st = gl_MultiTexCoord0.ts;
        ecNormal = gl_NormalMatrix * gl_Normal;
        vec4 ecPos4 = gl_ModelViewMatrix * gl_Vertex;
        ecPos = ecPos4.xyz/ecPos4.w;
}

//frag
uniform sampler2D diffuseMap;
varying vec3 ecPos;
varying vec3 ecNormal;
vec3 ecEye;
vec3 ecLight;

float diffuse(int lightId)
{
        ecLight = gl_LightSource[lightId].position.xyz - ecPos;
        return max(0.2, dot(normalize(ecNormal), normalize(ecLight)));
}

void main()
{                                       
        ecEye = normalize(-ecPos);                              
        gl_FragColor = diffuse(0) * texture2D(diffuseMap, gl_TexCoord[0].st);
}