Hello,

doesn’t anyone know how are following attributes in p3d_LightSourceParameters structure filled in?

```
uniform struct p3d_LightSourceParameters {
// Primary light color.
vec4 color;
// Light color broken up into components, for compatibility with legacy shaders.
vec4 ambient;
vec4 diffuse;
vec4 specular;
...
}
```

It behaves very strange in my shader. I use 2 lights in Panda app (one ambient and one directional which rotates around). In my shader I’m reading 8 lights from the array and summing the results. I’m using ambient, diffuse and specular values to calculate Phong lighting model but I also added functionality for switching between ambient only, diffuse only and specular only lighting modes.

If I use both lights then the ambient and specular values are black (visually). If I disable directional light in Panda app (only ambient light is active) then the ambient value is white and specular value black. In both cases diffuse values seem to be calculated which seems a bit odd -> I would expect for ambient light the diffuse attribute to be a zero vector.

I think worth mentioning that those 2 lights illuminate the object correctly if automatic shader is used.

Here is part of the shader calculating Phong lighting model (based on the OpenGL 4.0 Shading Language Cookbook - only difference is that I’m using multiple light sources and Panda3D):

```
vec3 phongModel(vec4 pos, vec3 norm) {
// Calculate light intensity
vec3 lightIntensity = vec3(0.0);
vec3 cameraVec = normalize(-pos.xyz);
for(int i = 0; i < p3d_LightSource.length(); i++) {
// Calculation of the vector to the light source
vec3 sourceVec = normalize(vec3(p3d_LightSource[i].position - pos));
// Reflection vector calculation (r = -s + 2 * dot(s, n) * n)
vec3 reflectVec = reflect(-sourceVec, norm);
// Assistance variable
float sDotN = max(dot(sourceVec, norm), 0.0);
// Ambient light component calculation (Ia = La * Ka)
vec3 aLight = p3d_LightSource[i].ambient.xyz * p3d_Material.ambient.xyz;
// Diffuse light component calculation (Id = Ld * Kd * dot(s, n))
vec3 dLight = p3d_LightSource[i].diffuse.xyz * p3d_Material.diffuse.xyz * sDotN;
// Specular light component calculation (Is = Ls * Ks * dot(r, v)^f)
vec3 sLight = sDotN > 0.0 ? \
p3d_LightSource[i].specular.xyz * p3d_Material.specular * \
pow(max(dot(reflectVec, cameraVec), 0.0), p3d_Material.shininess) : \
vec3(0.0);
// Final light intensity calculation (I = Ia + Id + Is)
lightIntensity += aLight + dLight + sLight;
}
return lightIntensity;
}
```

Any help or explanation what am I doing wrong is appreciated.