#version 450

float ambient = 0.1;
vec3 light_dir = normalize(vec3(2, 2, -1));
vec3 base_colour = vec3(1.0, 0.94, 0.8);

layout(location = 0) in vec3 frag_normal;
layout(location = 1) in vec4 light_pos;

layout(location = 0) out vec4 out_colour;

layout(binding = 2) uniform sampler2DShadow shadow_map;

void main()
{
	const float lambertian = max(dot(frag_normal, light_dir), 0.0);

	const float shadow_bias = 0.005;
	const vec3 proj_coords = light_pos.xyz / light_pos.w;
	const vec3 shadow_map_pos
		= vec3(0.5 * proj_coords.xy + 0.5, proj_coords.z);
	float shadow = texture(
		shadow_map,
		vec3(shadow_map_pos.xy, shadow_map_pos.z - shadow_bias));

	const float intensity = min(shadow * lambertian + ambient, 1.0);
	out_colour = vec4(intensity * base_colour, 1.0);
}