Galactica/crates/render/shaders/ui.wgsl

// INCLUDE: global uniform header

struct InstanceInput {
	@location(2) anchor: u32,
	@location(3) position: vec2<f32>,
	@location(4) angle: f32,
	@location(5) size: f32,
	@location(6) color_transform: vec4<f32>,
	@location(7) sprite_index: u32,
};

struct VertexInput {
	@location(0) position: vec3<f32>,
	@location(1) texture_coords: vec2<f32>,
}

struct VertexOutput {
	@builtin(position) position: vec4<f32>,
	@location(0) texture_coords: vec2<f32>,
	@location(1) texture_index: u32,
	@location(2) color_transform: vec4<f32>,
}

@group(0) @binding(0)
var texture_array: binding_array<texture_2d<f32>>;
@group(0) @binding(1)
var sampler_array: binding_array<sampler>;


// INCLUDE: animate.wgsl
// INCLUDE: anchor.wgsl

@vertex
fn vertex_main(
	vertex: VertexInput,
	instance: InstanceInput,
) -> VertexOutput {


	let window_dim = global_data.window_size / global_data.window_scale.x;
	let scale = instance.size / window_dim.y;
	let sprite_aspect = global_sprites[instance.sprite_index].aspect;

	// Apply scale and sprite aspect
	// Note that our mesh starts centered at (0, 0). This is important!
	var pos: vec2<f32> = vec2(
		vertex.position.x * scale * sprite_aspect,
		vertex.position.y * scale
	);

	// Apply rotation
	pos = mat2x2(
		vec2(cos(instance.angle), sin(instance.angle)),
		vec2(-sin(instance.angle), cos(instance.angle))
	) * pos;

	// Correct for screen aspect, preserving height
	pos = vec2(
		pos.x / global_data.window_aspect.x,
		pos.y
	);

	pos = pos + anchor(
		instance.anchor,
		instance.position,
		vec2(instance.size * sprite_aspect, instance.size)
	);

	var out: VertexOutput;
	out.position = vec4<f32>(pos, 1.0, 1.0);
	out.color_transform = instance.color_transform;



	// TODO: animate
	// Pick texture frame
	let t = global_atlas[u32(animate(instance.sprite_index, global_data.current_time.x, 0.0))];
	out.texture_index = u32(t.atlas_texture);
	out.texture_coords = vec2(t.xpos, t.ypos);
	if vertex.texture_coords.x == 1.0 {
		out.texture_coords = vec2(out.texture_coords.x + t.width, out.texture_coords.y);
	}
	if vertex.texture_coords.y == 1.0 {
		out.texture_coords = vec2(out.texture_coords.x, out.texture_coords.y + t.height);
	}

	return out;
}


@fragment
fn fragment_main(in: VertexOutput) -> @location(0) vec4<f32> {
	return textureSampleLevel(
		texture_array[in.texture_index],
		sampler_array[0],
		in.texture_coords,
		0.0
	).rgba * in.color_transform;
}