enable draw_index;

struct VertexInput {
    @location(0) position: vec2<f32>,
    @builtin(instance_index) draw_id: u32,
};

struct VertexOutput {
    @location(0) albedo: vec4<f32>,
    @builtin(position) position: vec4<f32>,
};

struct Face {
    transform: u32,
    colour: u32,
};

@group(0) @binding(0)
var<storage, read> faces: array<Face>;

@vertex
fn vs_main(
    input: VertexInput
) -> VertexOutput {
    let face = faces[input.draw_id];
    let transform = face.transform;
    let direction = transform & 0x07;
    let x = f32((transform & 0x00000F8) >> 3);
    let y = f32((transform & 0x0001F00) >> 8);
    let z = f32((transform & 0x003E000) >> 13);
    let w = f32((transform & 0x07C0000) >> 18);
    let h = f32((transform & 0xF800000) >> 23);

    var result: VertexOutput;
    result.position = vec4(input.position.x + x, input.position.y + y, z, 1.0);
    result.position.x += w * f32(input.position.x != 0);
    result.position.y += h * f32(input.position.y != 0);
    result.position = vec4(result.position.xy * 0.1, result.position.zw);

    result.albedo = vec4(
        f32(face.colour & 0x000000FF) / 255,
        f32((face.colour & 0x0000FF00) >> 8) / 255,
        f32((face.colour & 0x00FF0000) >> 16) / 255,
        f32((face.colour & 0xFF000000) >> 24) / 255,
    );

    return result;
}

struct FragmentOutput {
    @location(0) albedo: vec4<f32>,
    @location(1) chunk_id: u32,
}

@fragment
fn fs_main(vertex: VertexOutput) -> FragmentOutput {
    var output: FragmentOutput;
    output.albedo = vertex.albedo;
    output.chunk_id = 0;
    return output;
}