@group(0) @binding(0)
var<uniform> camera: mat4x4<f32>;

struct VertexInput {
	@location(0) position: vec2<f32>
}

struct InstanceInput {
	@location(1) position: vec2<f32>,
	@location(2) size: vec2<f32>,
	@location(3) rotation: f32,
	@location(4) z_layer: u32
}

struct VertexOutput {
	@builtin(position) clip_position: vec4<f32>
}

@vertex
fn vs_main(model: VertexInput, instance: InstanceInput) -> VertexOutput {
	var out: VertexOutput;

	// rotate the sprite
	let a = vec2<f32>(cos(instance.rotation), sin(instance.rotation));
	let b = vec2<f32>(-a[1], a[0]);
	let rotation = mat2x2<f32>(a, b);
	let rotated = rotation * model.position;

	// scale the sprite
	let scaled = rotated * instance.size;

	// move the sprite
	let position2d = scaled + instance.position;

	// camera stuff
	let position4d = vec4<f32>(position2d, 0.0, 1.0);
	let position = camera * position4d;

	out.clip_position = position;
	return out;
}

@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
	return vec4<f32>(1.0, 1.0, 1.0, 0.0);
}