# Objective
- Reduce the number of rebindings to enable batching of draw commands
## Solution
- Use the new `GpuArrayBuffer` for `MeshUniform` data to store all
`MeshUniform` data in arrays within fewer bindings
- Sort opaque/alpha mask prepass, opaque/alpha mask main, and shadow
phases also by the batch per-object data binding dynamic offset to
improve performance on WebGL2.
---
## Changelog
- Changed: Per-object `MeshUniform` data is now managed by
`GpuArrayBuffer` as arrays in buffers that need to be indexed into.
## Migration Guide
Accessing the `model` member of an individual mesh object's shader
`Mesh` struct the old way where each `MeshUniform` was stored at its own
dynamic offset:
```rust
struct Vertex {
@location(0) position: vec3<f32>,
};
fn vertex(vertex: Vertex) -> VertexOutput {
var out: VertexOutput;
out.clip_position = mesh_position_local_to_clip(
mesh.model,
vec4<f32>(vertex.position, 1.0)
);
return out;
}
```
The new way where one needs to index into the array of `Mesh`es for the
batch:
```rust
struct Vertex {
@builtin(instance_index) instance_index: u32,
@location(0) position: vec3<f32>,
};
fn vertex(vertex: Vertex) -> VertexOutput {
var out: VertexOutput;
out.clip_position = mesh_position_local_to_clip(
mesh[vertex.instance_index].model,
vec4<f32>(vertex.position, 1.0)
);
return out;
}
```
Note that using the instance_index is the default way to pass the
per-object index into the shader, but if you wish to do custom rendering
approaches you can pass it in however you like.
---------
Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com>
Co-authored-by: Elabajaba <Elabajaba@users.noreply.github.com>
# Objective
- Add a type for uploading a Rust `Vec<T>` to a GPU `array<T>`.
- Makes progress towards https://github.com/bevyengine/bevy/issues/89.
## Solution
- Port @superdump's `BatchedUniformBuffer` to bevy main, as a fallback
for WebGL2, which doesn't support storage buffers.
- Rather than getting an `array<T>` in a shader, you get an `array<T,
N>`, and have to rebind every N elements via dynamic offsets.
- Add `GpuArrayBuffer` to abstract over
`StorageBuffer<Vec<T>>`/`BatchedUniformBuffer`.
## Future Work
Add a shader macro kinda thing to abstract over the following
automatically:
https://github.com/bevyengine/bevy/pull/8204#pullrequestreview-1396911727
---
## Changelog
* Added `GpuArrayBuffer`, `GpuComponentArrayBufferPlugin`,
`GpuArrayBufferable`, and `GpuArrayBufferIndex` types.
* Added `DynamicUniformBuffer::new_with_alignment()`.
---------
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Teodor Tanasoaia <28601907+teoxoy@users.noreply.github.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
Co-authored-by: Vincent <9408210+konsolas@users.noreply.github.com>
Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com>
