source: data/branches/powerups/shaders/bump.frag @ 3593

 uniform sampler2D BumpTex; //The bump-map 
 uniform sampler2D DecalTex; //The texture
 varying vec4 passcolor; //Receiving the vertex color from the vertex shader
 varying vec3 LightDir; //Receiving the transformed light direction 
 void main() 
 {
   //Get the color of the bump-map
   vec3 BumpNorm = vec3(texture2D(BumpTex, gl_TexCoord[0].xy));
   //Get the color of the texture
   vec3 DecalCol = vec3(texture2D(DecalTex, gl_TexCoord[0].xy));
   //Expand the bump-map into a normalized unsigned vector float
   BumpNorm = (BumpNorm -0.5) * 2.0;
   //Find the dot product between the light direction and the normal
   NdotL = max(dot(BumpNorm, LightDir), 0.0);
   //Calculate the final color gl_FragColor
   vec3 diffuse = NdotL * passcolor.xyz * DecalCol;
   //Set the color of the fragment...  If you want specular lighting or other types add it here
   vec4(diffuse, passcolor.w);
 }