indexing into wgsl array with a variable?

Question

i am making a compute shader to use with bevy 0.12 so im using wgsl. i want to index into an array like this:

fn is_boxed_in(x: u32, y: u32, z: u32, voxels: array<ShaderVoxel, 4096>) -> bool {
    if check_for_voxel(voxels[voxel_to_1d(min(CHUNK_SIZE - 1u, x + 1u), y, z)])
        && check_for_voxel(voxels[voxel_to_1d(max(0u, x - 1u), y, z)])
        && check_for_voxel(voxels[voxel_to_1d(x, min(CHUNK_SIZE - 1u, y + 1u), z)])
        && check_for_voxel(voxels[voxel_to_1d(x, max(0u, y - 1u), z)])
        && check_for_voxel(voxels[voxel_to_1d(x, y, min(CHUNK_SIZE - 1u, z + 1u))])
        && check_for_voxel(voxels[voxel_to_1d(x, y, max(0u, z - 1u))])
    {
        return true;
    }

    return false;
}

but im getting this error:

Function [6] 'is_boxed_in' is invalid.

WithSpan {
    inner: Function {
        handle: [6],
        name: "is_boxed_in",
        source: Expression {
            handle: [10],
            source: IndexMustBeConstant(
                [4],
            ),
        },
    },
    spans: [
        (
            Span {
                start: 2094,
                end: 2700,
            },
            "naga::Function [6]",
        ),
        (
            Span {
                start: 2201,
                end: 2256,
            },
            "naga::Expression [10]",
        ),
    ],
}

is it possible and if so how do i index into this array? this is where i am calling the function:

@compute @workgroup_size(16, 16, 1)
fn init(@builtin(global_invocation_id) global_id: vec3<u32>){
    let index = voxel_to_1d(global_id.x, global_id.y, global_id.z);

    var iter = 0u;
    while iter < arrayLength(&chunks.chunks) {
        var chunk = chunks.chunks[iter];
        var voxels = chunk.voxels;
        for (var i = 0; i < 4096; i += 1){
            var voxel = voxels[i];
            if voxel.id != 0u && !is_boxed_in(voxel_to_3d(i).x, voxel_to_3d(i).y, voxel_to_3d(i).z, voxels){
                //gen normal
            }
        }
        iter += 1u;
    }
}

any help would be super appreciated :)

Dávid Tóth · Accepted Answer · 2025-03-30 13:09:45Z

0

Sidenote: With this much data for the voxels you're better off using module_scope declaration for it. You can reach it as well, and still set the data like you normally would.

I believe what you were looking for was resolved last 25Oct; Refer to this issue.

I'd quote a relevant part but if my understanding is correct your code should work as is in latest versions!

answered Mar 30 at 13:09

Dávid Tóth

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