// global uniform sampler2D diffuse_curve: repeat_disable;
// global uniform float specular_smoothness;
// global uniform float fresnel_smoothness;
uniform float specular_smoothness = 0.05;
uniform float fresnel_smoothness = 0.05;

float diffuse_sample(vec3 light, vec3 normal) {
	// float remapped = (dot(light, normal) - (-1.0))/(1.0 - (-1.0));
	// return texture(diffuse_curve, vec2(remapped, 1.0)).r;
	return (dot(light, normal) - (-1.0))/(1.0 - (-1.0));
}

float is_lit(vec3 light, vec3 normal, float attenuation) {
	return attenuation * diffuse_sample(light, normal);
}

vec3 diffuse_light(
		vec3 albedo,
		vec3 light_color,
		vec3 light,
		vec3 normal,
		float attenuation
) {
	// return albedo * light_color * is_lit(light, normal, attenuation);
	return light_color * is_lit(light, normal, attenuation);
}

vec3 specular_light(
		vec3 light_color,
		vec3 specular_color,
		float specular_strength,
		vec3 normal,
		vec3 view,
		vec3 light,
		float attenuation
) {
	vec3 half = normalize(view + light);
	float gloss = pow(2.0, 8.0 * (1.0 - specular_strength));
	float intensity = pow(dot(normal, half), gloss * gloss);
	return light_color
			* specular_color
			* is_lit(light, normal, attenuation)
			* smoothstep(
					0.05,
					0.05 + specular_smoothness,
					intensity
			);
}

vec3 fresnel_light(
		vec3 light_color,
		vec3 fresnel_color,
		float fresnel_strength,
		vec3 normal,
		vec3 view,
		vec3 light,
		float attenuation
) {
	float fresnel_dot = 1.0 - dot(normal, view);
	float fresnel_threshold = pow((1.0 - fresnel_strength), dot(light, normal));
	return light_color
			* fresnel_color
			* is_lit(light, normal, attenuation)
			* smoothstep(
					fresnel_threshold - fresnel_smoothness / 2.0,
					fresnel_threshold + fresnel_smoothness / 2.0,
					fresnel_dot
			);
}