# Objective
- Make follow-up changes from #18866
## Solution
- Switch from the on add observer to an on insert hook
- Make the component immutable
- Remove required components
## Testing
- `tilemap_chunk` example
# Objective
#19410 added support for resizing images "in place" meaning that their
data was copied into the new texture allocation on the CPU. However,
there are some scenarios where an image may be created and populated
entirely on the GPU. Using this method would cause data to disappear, as
it wouldn't be copied into the new texture.
## Solution
When an image is resized in place, if it has no data in it's asset,
we'll opt into a new flag `copy_on_resize` which will issue a
`copy_texture_to_texture` command on the old allocation.
To support this, we require passing the old asset to all `RenderAsset`
implementations. This will be generally useful in the future for
reducing things like buffer re-allocations.
## Testing
Tested using the example in the issue.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
An attempt to start building a base for first-party tilemaps (#13782).
The objective is to create a very simple tilemap chunk rendering plugin
that can be used as a building block for 3rd-party tilemap crates, and
eventually a first-party tilemap implementation.
## Solution
- Introduces two user-facing components, `TilemapChunk` and
`TilemapChunkIndices`, and a new material `TilemapChunkMaterial`.
- `TilemapChunk` holds the chunk and tile sizes, and the tileset image
- The tileset image is expected to be a layered image for use with
`texture_2d_array`, with the assumption that atlases or multiple images
would go through an asset loader/processor. Not sure if that should be
part of this PR or not..
- `TilemapChunkIndices` holds a 1d representation of all of the tile's
Option<u32> index into the tileset image.
- Indices are fixed to the size of tiles in a chunk (though maybe this
should just be an assertion instead?)
- Indices are cloned and sent to the shader through a u32 texture.
## Testing
- Initial testing done with the `tilemap_chunk` example, though I need
to include some way to update indices as part of it.
- Tested wasm with webgl2 and webgpu
- I'm thinking it would probably be good to do some basic perf testing.
---
## Showcase
```rust
let chunk_size = UVec2::splat(64);
let tile_size = UVec2::splat(16);
let indices: Vec<Option<u32>> = (0..chunk_size.x * chunk_size.y)
.map(|_| rng.gen_range(0..5))
.map(|i| if i == 0 { None } else { Some(i - 1) })
.collect();
commands.spawn((
TilemapChunk {
chunk_size,
tile_size,
tileset,
},
TilemapChunkIndices(indices),
));
```
