Multiple worlds

[splashdust]

Add support for multiple parallell world instances

Breaking changes:

Configuration is now supplied when adding the plugin

// First declare a config struct. It needs to derive `Resource`, `Clone` and `Default`
#[derive(Resource, Clone, Default)]
struct MyWorld;

// Then implement the `VoxelWorldConfig` trait for it:
impl VoxelWorldConfig for MyWorld {
    // All the trait methods have defaults, so you only need to add the ones you want to alter
    fn spawning_distance(&self) -> u32 {
       15
    }
}

Then when adding the plugin:

.add_plugins(VoxelWorldPlugin::with_config(MyWorld))

If you don't want to change any default config, you can simply do this:

.add_plugins(VoxelWorldPlugin::default())

Adding multiple worlds follows the same pattern. Just create different configuration structs and add a VoxelWorldPlugin for each.

.add_plugins(VoxelWorldPlugin::with_config(MyOtherWorld))

Each world instance can have it's own configuration and will keep track of it's own set of voxel data and chunks.

The VoxelWorld system param now needs a type parameter to specify which world instance you want to select

The configuration struct adds the config values and its type also acts as a marker for the world instance.

fn my_system(
  my_voxel_world: VoxelWorld<MyWorld>,
  my_other_voxel_world: VoxelWorld<MyOtherWorld>
) {
  // Set a voxel in `my_voxel_world`
  my_voxel_world.set_voxel(pos, WorldVoxel::Solid(voxel_type))

  // Set a voxel in `my_other_voxel_world`
  my_other_voxel_world.set_voxel(pos, WorldVoxel::Solid(voxel_type))
}

If you initialized the plugin with ::default(), you still need to explicitly specify the instance as DefaultWorld:

fn my_system(voxel_world: VoxelWorld<DefaultWorld>) { ... }

The VoxelWorldRaycast system param now also requires the same config type paramter as described above.