bevy/crates/bevy_sprite/src/mesh2d/mesh2d_functions.wgsl

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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
#define_import_path bevy_sprite::mesh2d_functions
fn mesh2d_position_local_to_world(model: mat4x4<f32>, vertex_position: vec4<f32>) -> vec4<f32> {
return model * vertex_position;
}
fn mesh2d_position_world_to_clip(world_position: vec4<f32>) -> vec4<f32> {
return view.view_proj * world_position;
}
// NOTE: The intermediate world_position assignment is important
// for precision purposes when using the 'equals' depth comparison
// function.
fn mesh2d_position_local_to_clip(model: mat4x4<f32>, vertex_position: vec4<f32>) -> vec4<f32> {
let world_position = mesh2d_position_local_to_world(model, vertex_position);
return mesh2d_position_world_to_clip(world_position);
}
fn mesh2d_normal_local_to_world(vertex_normal: vec3<f32>) -> vec3<f32> {
return mat3x3<f32>(
mesh.inverse_transpose_model[0].xyz,
mesh.inverse_transpose_model[1].xyz,
mesh.inverse_transpose_model[2].xyz
) * vertex_normal;
}
fn mesh2d_tangent_local_to_world(model: mat4x4<f32>, vertex_tangent: vec4<f32>) -> vec4<f32> {
return vec4<f32>(
mat3x3<f32>(
model[0].xyz,
model[1].xyz,
model[2].xyz
) * vertex_tangent.xyz,
vertex_tangent.w
);
}