[layout(std140)]
struct PointLight
{
	color: vec3<f32>,
	position: vec3<f32>,

	constant: f32,
	linear: f32,
	quadratic: f32,
}

[layout(std140)]
struct SpotLight
{
	color: vec3<f32>,
	position: vec3<f32>,
	direction: vec3<f32>,

	constant: f32,
	linear: f32,
	quadratic: f32,

	innerAngle: f32,
	outerAngle: f32,
}

external
{
	[binding(0)] colorTexture: sampler2D<f32>,
	[binding(1)] normalTexture: sampler2D<f32>,
	[binding(2)] positionTexture: sampler2D<f32>,
	[binding(3)] lightParameters: uniform<SpotLight>
	//[binding(3)] lightParameters: uniform<PointLight>
}

[layout(std140)]
struct FragOut
{
	[location(0)] color: vec4<f32>
}

[layout(std140)]
struct VertIn
{
	[location(0)] pos: vec3<f32>,
	[location(1)] uv: vec2<f32>
}

[layout(std140)]
struct VertOut
{
	[location(0)] uv: vec2<f32>,
	[builtin(position)] position: vec4<f32>
}

[entry(frag)]
fn main(input: VertOut) -> FragOut
{
	let normal = normalTexture.Sample(input.uv).xyz * 2.0 - vec3<f32>(1.0, 1.0, 1.0);
	let position = positionTexture.Sample(input.uv).xyz;

	let attenuation = compute_attenuation(position, normal);

	let output: FragOut;
	output.color = vec4<f32>(lightParameters.color, 1.0) * attenuation * colorTexture.Sample(input.uv);

	return output;
}

[entry(vert)]
fn main(input: VertIn) -> VertOut
{
	let output: VertOut;
	output.uv = input.uv;
	output.position = vec4<f32>(input.pos, 1.0);

	return output;
}

fn compute_attenuation(worldPos: vec3<f32>, normal: vec3<f32>) -> f32
{
	let distance = length(lightParameters.position - worldPos);

	let posToLight = (lightParameters.position - worldPos) / distance;
	let lambert = dot(normal, posToLight);

	let curAngle = dot(lightParameters.direction, -posToLight);
	let innerMinusOuterAngle = lightParameters.innerAngle - lightParameters.outerAngle;

	let attenuation = 1.0 / (lightParameters.constant + lightParameters.linear * distance + lightParameters.quadratic * (distance * distance));
	attenuation = attenuation * lambert * max((curAngle - lightParameters.outerAngle) / innerMinusOuterAngle, 0.0);

	return attenuation;
}