#version 330

uniform sampler2D texture0;
uniform vec4 colDiffuse;

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;

in vec2 frag_texcoord;
in vec4 frag_colour;
in vec3 frag_normal;

out vec4 finalColor;

void main() {
	vec4 texel = texture(texture0, frag_texcoord) * frag_colour;

	if (texel.a < 0.5) {
		discard;
	}

	texel.rgb += colDiffuse.rgb;

	vec3 normal = normalize(frag_normal);

	if (!gl_FrontFacing) {
		normal = -normal;
	}

	float sun_diffuse = max(dot(normal, sun_direction), 0.0);
	float moon_diffuse = max(dot(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;

	vec3 lighting = max(
		ambient_light + sun_light + moon_light,
		vec3(0.0)
	);

	finalColor = vec4(texel.rgb * lighting, 1.0);
}