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struct Camera {
scale: vec2f,
centre: vec2f,
};
struct Instance {
centre: vec2f,
cos_sin: vec2f,
half_size: vec2f,
dims: vec2u,
cell_offset: u32,
};
@group(0) @binding(0) var<uniform> camera: Camera;
@group(0) @binding(1) var<storage, read> palette: array<vec4f>;
@group(0) @binding(2) var<storage, read> instances: array<Instance>;
@group(0) @binding(3) var<storage, read> cells: array<u32>;
struct VertexOutput {
@builtin(position) clip_position: vec4<f32>,
@location(0) world: vec2<f32>,
@location(1) @interpolate(flat) instance: u32,
};
@vertex
fn vs_main(
@builtin(vertex_index) i: u32,
@builtin(instance_index) n: u32,
) -> VertexOutput {
let instance = instances[n];
// (-1,-1),(1,-1),(-1,1),(1,1)
let corner = vec2f(f32(i & 1u), f32(i >> 1u)) * 2.0 - 1.0;
let local = corner * (instance.half_size + 2.0);
let world = instance.centre + vec2f(
local.x * instance.cos_sin.x - local.y * instance.cos_sin.y,
local.x * instance.cos_sin.y + local.y * instance.cos_sin.x,
);
var out: VertexOutput;
out.clip_position = vec4f((world - camera.centre) * camera.scale, 0.0, 1.0);
out.world = world;
out.instance = n;
return out;
}
@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
let instance = instances[in.instance];
let d = in.world - instance.centre;
let q = floor(d) + vec2f(0.5);
let local = vec2f(
q.x * instance.cos_sin.x + q.y * instance.cos_sin.y,
-q.x * instance.cos_sin.y + q.y * instance.cos_sin.x,
) + instance.half_size;
let cell = vec2i(floor(local));
if any(cell < vec2i(0)) || any(cell >= vec2i(instance.dims)) {
discard;
}
let idx = instance.cell_offset + u32(cell.y) * instance.dims.x + u32(cell.x);
let material = (cells[idx >> 2u] >> ((idx & 3u) * 8u)) & 0xFFu;
if material == 0u {
discard;
}
return palette[material];
}
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