#version 330

in vec3 vertexPosition;
in vec2 vertexTexCoord;
in vec3 vertexNormal;
in vec4 vertexColor;

uniform mat4 mvp;
uniform mat4 matNormal;

uniform vec3 sun_direction;
uniform vec3 sun_colour;
uniform float sun_intensity;

uniform vec3 moon_direction;
uniform vec3 moon_colour;
uniform float moon_intensity;

uniform vec3 ambient_colour;
uniform float ambient_intensity;

out vec2 frag_texcoord;
out vec4 frag_colour;
out vec3 frag_lighting;

void
main() {
	vec3 world_normal = normalize(
		(matNormal * vec4(vertexNormal, 0.0)).xyz
	);

	float sun_diffuse = max(
		dot(world_normal, sun_direction),
		0.0
	);

	float moon_diffuse = max(
		dot(world_normal, moon_direction),
		0.0
	);

	vec3 ambient_light =
		ambient_colour * ambient_intensity;

	vec3 sun_light =
		sun_colour *
		sun_intensity *
		sun_diffuse;

	vec3 moon_light =
		moon_colour *
		moon_intensity *
		moon_diffuse;

	frag_lighting =
		ambient_light +
		sun_light +
		moon_light;

	frag_texcoord = vertexTexCoord;
	frag_colour = vertexColor;

	gl_Position = mvp * vec4(vertexPosition, 1.0);
}