float light = 0;
for(; light < iLights; light += 1.0) {
	// light ray
	float3 ray = vtx.wpos - vecLightPos[light].xyz;
	
	// spotlight factor
	float depth = saturate(dot(vecLightDir[light].xyz, ray) / vecLightPos[light].w);
	float spot = 1.0 - saturate(length(cross(vecLightDir[light].xyz, ray)) / (vecLightPos[light].w * depth));
	
	// normalize the light ray
	float dist = length(ray);
	ray /= dist; 
	
	// attenuation
	float att = 1.0 - saturate(dist / vecLightPos[light].w);
	
	// final light factor
	att *= vecLightDir[light].w ? spot : 1.0;
	
	// diffuse term
	diffuse += vecLightColor[light].rgb * saturate(-dot(ray, vtx.normal.xyz)) * att;
	
	// specular term
	refl = reflect(ray, vtx.normal.xyz);
	specular += vecLightColor[light].rgb * pow(saturate(-dot(refl, vecViewDir.xyz)), fPower) * att;
}