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

	radius: f32,
	invRadius: f32,
}

[layout(std140)]
struct SpotLight
{
	transformMatrix: mat4<f32>,

	color: vec3<f32>,
	position: vec3<f32>,
	direction: vec3<f32>,

	radius: f32,
	invRadius: f32,

	innerAngle: f32,
	outerAngle: f32
}

[layout(std140)]
struct ViewerData
{
	projectionMatrix: mat4<f32>,
	invProjectionMatrix: mat4<f32>,
	viewMatrix: mat4<f32>,
	invViewMatrix: mat4<f32>,
	viewProjMatrix: mat4<f32>,
	invViewProjMatrix: mat4<f32>,
	renderTargetSize: vec2<f32>,
	invRenderTargetSize: vec2<f32>,
	eyePosition: vec3<f32>
}

[set(0)]
external
{
	[binding(0)] viewerData: uniform<ViewerData>
}

[set(1)]
external
{
	[binding(0)] colorTexture: sampler2D<f32>,
	[binding(1)] normalTexture: sampler2D<f32>,
	[binding(2)] positionTexture: sampler2D<f32>,
}

[set(2)]
external
{
	[binding(0)] lightParameters: uniform<SpotLight>,
}

struct FragIn
{
	[builtin(fragcoord)] fragcoord: vec4<f32>
}

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

struct VertIn
{
	[location(0)] pos: vec3<f32>
}

struct VertOut
{
	[builtin(position)] position: vec4<f32>
}

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

	let attenuation = compute_attenuation(position, normal);

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

	return output;
}

[entry(vert)]
fn main(input: VertIn) -> VertOut
{
	let output: VertOut;
	output.position = viewerData.projectionMatrix * viewerData.viewMatrix * lightParameters.transformMatrix * 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 = max(1.0 - distance * lightParameters.invRadius, 0.0);
	attenuation = attenuation * lambert * max((curAngle - lightParameters.outerAngle) / innerMinusOuterAngle, 0.0);

	return attenuation;
}