Commit graph

1 commit

Author SHA1 Message Date
Robert Swain
b333386271 Add reusable shader functions for transforming position/normal/tangent (#4901)
# Objective

- Add reusable shader functions for transforming positions / normals / tangents between local and world / clip space for 2D and 3D so that they are done in a simple and correct way
- The next step in #3969 so check there for more details.

## Solution

- Add `bevy_pbr::mesh_functions` and `bevy_sprite::mesh2d_functions` shader imports
  - These contain `mesh_` and `mesh2d_` versions of the following functions:
    - `mesh_position_local_to_world`
    - `mesh_position_world_to_clip`
    - `mesh_position_local_to_clip`
    - `mesh_normal_local_to_world`
    - `mesh_tangent_local_to_world`
- Use them everywhere where it is appropriate
  - Notably not in the sprite and UI shaders where `mesh2d_position_world_to_clip` could have been used, but including all the functions depends on the mesh binding so I chose to not use the function there
- NOTE: The `mesh_` and `mesh2d_` functions are currently identical. However, if I had defined only `bevy_pbr::mesh_functions` and used that in bevy_sprite, then bevy_sprite would have a runtime dependency on bevy_pbr, which seems undesirable. I also expect that when we have a proper 2D rendering API, these functions will diverge between 2D and 3D.

---

## Changelog

- Added: `bevy_pbr::mesh_functions` and `bevy_sprite::mesh2d_functions` shader imports containing `mesh_` and `mesh2d_` versions of the following functions:
  - `mesh_position_local_to_world`
  - `mesh_position_world_to_clip`
  - `mesh_position_local_to_clip`
  - `mesh_normal_local_to_world`
  - `mesh_tangent_local_to_world`

## Migration Guide

- The `skin_tangents` function from the `bevy_pbr::skinning` shader import has been replaced with the `mesh_tangent_local_to_world` function from the `bevy_pbr::mesh_functions` shader import
2022-06-14 00:32:33 +00:00