#version 440
out vec4 FragColor;

in vec2 uv;

uniform sampler2D pos_tex;
uniform sampler2D normal_tex;
uniform sampler2D color_tex;

struct Light {
    vec3 Position;
    vec3 Color;       
};

uniform int NLights;
uniform Light lights[64];

uniform vec3 view_pos;

void main()
{ 
   vec3 FragPos = texture(pos_tex, uv).rgb;
   vec3 Normal = texture(normal_tex, uv).rgb;
   vec3 Albedo = texture(color_tex, uv).rgb;
   float Specular = 0.5f;
    
   // then calculate lighting as usual
   vec3 lighting = Albedo * 0.1; // hard-coded ambient component
   vec3 viewDir = normalize(view_pos - FragPos);
   for (int i = 0; i < NLights; ++i)
   {
		vec3 L = normalize(lights[i].Position.xyz - FragPos);
		vec3 V = normalize(view_pos - FragPos);
		vec3 H = normalize(V + L);
        
        vec3 diffuse = max(dot(Normal, L), 0.0) * Albedo * lights[i].Color;
        // specular        
        float spec = pow(max(dot(Normal, H), 0.0), 16.0);
        vec3 specular = lights[i].Color * spec * Specular;        
        lighting += diffuse + specular;   
    }
    
    FragColor = vec4(lighting, 1.0);
}