bevy/assets
Robert Swain e6405bb7b4
Use GpuArrayBuffer for MeshUniform (#9254)
# 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>
2023-07-30 13:17:08 +00:00
..
android-res/mipmap-mdpi android example polish (#845) 2020-11-11 16:31:16 -08:00
branding Minor Dark/Light Logo Tweak (#4051) 2022-02-27 02:09:42 +00:00
data Asset system rework and GLTF scene loading (#693) 2020-10-18 13:48:15 -07:00
environment_maps EnvironmentMapLight, BRDF Improvements (#7051) 2023-02-09 16:46:32 +00:00
fonts Add the license for the FiraMono font (#3589) 2022-05-06 19:29:43 +00:00
models Add morph targets (#8158) 2023-06-22 20:00:01 +00:00
pixel Add pixelated Bevy to assets and an example (#6408) 2022-11-14 22:15:46 +00:00
scenes (De) serialize resources in scenes (#6846) 2023-03-20 21:17:02 +00:00
shaders Use GpuArrayBuffer for MeshUniform (#9254) 2023-07-30 13:17:08 +00:00
sounds Add simple collision sound to breakout (#4331) 2022-04-14 20:20:38 +00:00
textures Add parallax mapping to bevy PBR (#5928) 2023-04-15 10:25:14 +00:00