option HAS_DIFFUSE_TEXTURE: bool;
option HAS_ALPHA_TEXTURE: bool;
option ALPHA_TEST: bool;

const HasUV = ALPHA_TEST && (HAS_DIFFUSE_TEXTURE || HAS_ALPHA_TEXTURE);

[layout(std140)]
struct BasicSettings
{
	AlphaThreshold: f32,
	DiffuseColor: vec4<f32>
}

[layout(std140)]
struct InstanceData
{
	worldMatrix: mat4<f32>,
	invWorldMatrix: mat4<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>
}

external
{
	[set(0), binding(0)] viewerData: uniform<ViewerData>,
	[set(1), binding(0)] instanceData: uniform<InstanceData>,
	[set(2), binding(0)] settings: uniform<BasicSettings>,
	[set(2), binding(2)] MaterialAlphaMap: sampler2D<f32>,
}

// Fragment stage
struct FragIn
{
	[location(0), cond(HasUV)] uv: vec2<f32>
}

[entry(frag), cond(ALPHA_TEST)]
fn main(input: FragIn)
{
	let alpha = settings.DiffuseColor.a;
	const if (HAS_DIFFUSE_TEXTURE)
		// TODO: alpha *= MaterialDiffuseMap.Sample(input.uv).a;
		alpha = alpha * MaterialDiffuseMap.Sample(input.uv).a;

	const if (HAS_ALPHA_TEXTURE)
		// TODO: alpha *= MaterialAlphaMap.Sample(input.uv).x
		alpha = alpha * MaterialAlphaMap.Sample(input.uv).x;

	// TODO: const assert?
	if (alpha < settings.AlphaThreshold)
		discard;
}

[entry(frag), cond(!ALPHA_TEST)]
fn main() {}

// Vertex stage
struct VertIn
{
	[location(0)] pos: vec3<f32>,
	[location(1), cond(HasUV)] uv: vec2<f32>
}

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

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

	const if (HasUV)
		output.uv = input.uv;

	return output;
}