#version 330

layout(location = 0) in vec3 v_position;
layout(location = 1) in vec3 v_normal;
layout(location = 2) in vec2 v_texture_coord;

// Uniform properties
uniform mat4 Model;
uniform mat4 View;
uniform mat4 Projection;

// Uniforms for light properties
uniform vec3 light_position;
uniform vec3 eye_position;
uniform float material_kd;
uniform float material_ks;
uniform int material_shininess;

uniform vec3 object_color;

// Output value to fragment shader
out vec3 color;

void main()
{
	// TODO: compute world space vectors
	vec3 world_pos = (Model * vec4(v_position,1)).xyz;
	vec3 Npos = normalize( mat3(Model) * v_normal );

	vec3 Lpos = normalize( light_position - world_pos );
	vec3 Vpos = normalize( eye_position - world_pos );
	vec3 Hpos = normalize( Lpos + Vpos );

	// TODO: define ambient light component
	float ambient_light = 0.25;

	// TODO: compute diffuse light component
	float dotNL = dot(Npos,Lpos);
	float diffuse_light;
	diffuse_light = max(dotNL, 0);

	// TODO: compute specular light component
	float _specular_light = 0;

	if (dotNL > 0)
	{
		_specular_light = pow(dotNL, material_shininess);
	}

	float specular_light = (dotNL > 0 ? _specular_light : 0);

	float light = ambient_light + diffuse_light + specular_light;

	float look = distance(world_pos, eye_position);
	const float x = .01, y = .02, z = 1;
	float atten = 1 / (x * look * look + y * look + z);
	color = light * object_color * atten;

	gl_Position = Projection * View * Model * vec4(v_position, 1.0);
}