Opposite Z order than expected for iso/hex tiles that extend past grid height

[gak]

The rendered tiles:

The lower tiles should render above the higher tiles, right? Not sure if this is a bug or my set up. I'm using the current main branch, and the same happens on 0.7.0.

Here's the atlas. I've picked out the 3 different coloured cubes. These are 32x32 tiles with a grid size of 32x16:

I looked at the shader and there is the Z axis being set from 0..1 depending on the Y axis, which to me seems like the right thing to do to.

bevy_ecs_tilemap/src/render/shaders/staggered_iso.wgsl

Line 30 in 6a6fb43

out.world_position = mesh.model * vec4<f32>(vec3<f32>(positions[v_index % 4u], 1.0 - (tile_z.y / tilemap_data.map_size.y)), 1.0);

Specifically this argument: 1.0 - (tile_z.y / tilemap_data.map_size.y).

I wasn't sure if Y was going the wrong direction along with Z, so I reversed the ordering by trying just tile_z.y / tilemap_data.map_size.y with the same result. I also messed around with bigger Z values with interesting results (where Z left view frustum) but nothing how I wanted.

Also tried messing with Camera.depth_calculation and Orthographic.depth_calculation without any luck.

I copied the basic example with a few changes. Here's the startup system:

pub fn init(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn_bundle(Camera2dBundle {
        ..Default::default()
    });

    let texture_handle: Handle<Image> =
        asset_server.load("isometric-sandbox-32x32/isometric-sandbox-sheet.png");

    let tilemap_size = TilemapSize { x: 4, y: 4 };
    let tilemap_entity = commands.spawn().id();
    let mut tile_storage = TileStorage::empty(tilemap_size);

    for x in 0..tilemap_size.x {
        for y in 0..tilemap_size.y {
            let tile_pos = TilePos { x, y };

            let texture = match thread_rng().gen_range(0..3) {
                0 => 0,
                1 => 18,
                2 => 36,
                _ => unreachable!(),
            };

            let tile_entity = commands
                .spawn()
                .insert_bundle(TileBundle {
                    position: tile_pos,
                    tilemap_id: TilemapId(tilemap_entity),
                    texture: TileTexture(texture),
                    visible: Default::default(),
                    color: Default::default(),
                    ..Default::default()
                })
                .id();
            tile_storage.set(&tile_pos, Some(tile_entity));
        }
    }

    let tile_size = TilemapTileSize { x: 32.0, y: 32.0 };
    let grid_size = TilemapGridSize { x: 32.0, y: 16.0 };

    commands
        .entity(tilemap_entity)
        .insert_bundle(TilemapBundle {
            grid_size,
            size: tilemap_size,
            storage: tile_storage,
            texture: TilemapTexture(texture_handle),
            tile_size,
            map_type: TilemapType::Isometric {
                neighbors_include_diagonals: true,
                coord_system: IsoCoordSystem::Staggered,
            },
            ..Default::default()
        });
}

[Affinator]

And to add another point: The tiles are always centered on the grid. If I look at this tileset/atlas, it may be wanted that the top of the cube aligns with the grid. It has the same shape as a 2D-Tile at least.

[bzm3r]

@gak We have made some changes to the renderer now. Can you try again and tell me what happens? (I don't think the issue is fixed, but I want to see what has changed, and I want to try and better understand the troubles you were running into, in the context of the current state of the code.)

[bzm3r]

@gak Oh, also, I just realized...the tiles do not have z-position at all. It is ignored. It is not used in any meaningful way. If you want to stack tiles, you have to use separate tilemaps. All tiles in the same tilemap have the same z-value.

[gak]

Thanks, I suspected as much after my futile attempts. :)

[bzm3r]

@gak yeah, sorry about this. We'll be working on implementing this feature next! #200 (comment)