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const AMBIENT_LIGHT = vec4f(0.4, 0.4, 0.4, 1.0);
const LIGHT_RESOLUTION = 1.0;
struct Camera {
scale: vec2f,
centre: vec2f,
};
struct Lighting {
origin: vec2f,
_padding: 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>;
@group(0) @binding(4) var lighting: texture_2d_array<f32>;
@group(0) @binding(5) var light_sampler: sampler;
@group(0) @binding(6) var<uniform> light_params: Lighting;
struct VertexOutput {
@builtin(position) clip_position: vec4f,
@location(0) world: vec2f,
@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) vec4f {
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;
}
var total = vec3f(0.0);
let light_dims = vec2f(textureDimensions(lighting));
let light_texel = (in.world - light_params.origin) * LIGHT_RESOLUTION;
let light_uv = light_texel / light_dims;
for (var d = 0u; d < 4u; d++) {
total += textureSample(lighting, light_sampler, light_uv, d).rgb;
}
let light = vec4f(total.r, total.g, total.b, 1.0);
return palette[material] * (light + AMBIENT_LIGHT);
}
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