uniform vec4 U_AmbientMaterial;
uniform vec4 U_AmbientLight;
uniform vec4 U_DiffuseMaterial;
uniform vec4 U_DiffuseLight;
uniform vec4 U_SpecularMaterial;
uniform vec4 U_SpecularLight;
uniform vec4 U_LightPos;
uniform vec4 U_CameraPos;
varying vec4 V_Normal;
varying vec4 V_WorldPos;

void main(){
	//ambient
	vec4 ambientColor = U_AmbientMaterial * U_AmbientLight;

	//diffuse
	vec3 n = normalize(V_Normal.xyz);
	vec3 l = normalize(U_LightPos - vec3(0));
	float duffuseIntensity = max(0.0, dot(l,n));
	vec4 duffuseColor = U_DiffuseMaterial * U_DiffuseLight * duffuseIntensity;

	//specular
	vec4 specularColor = vec4(0);
	if(duffuseIntensity > 0){
		vec3 rd = normalize(reflect(-l,n));
		vec3 vd = normalize((U_CameraPos - V_WorldPos).xyz);
		float specularIntensity = pow(max(0.0,dot(vd,rd)), 128);
		specularColor = U_SpecularMaterial * U_SpecularLight * specularIntensity;
	}

	gl_FragColor = ambientColor + duffuseColor + specularColor;
}