# Objective
- Fixes#18081
- Enable use-cases like getting UVs or texture colors for the hit point
(which are currently not possible due to this bug).
## Solution
- Return the triangle index instead of the first vertex index of the
triangle.
## Testing
Tested successfully with my project which does a raycast to get the UV
coordinates of the hit. My code:
```rust
fn get_uv(
mesh: &Mesh,
attribute: &MeshVertexAttribute,
hit: &RayMeshHit,
_gizmos: &mut Gizmos,
) -> Result<Vec2> {
let (a, b, c) = get_indices(mesh, hit)?;
let attrs = mesh
.attribute(*attribute)
.ok_or_eyre(format!("Attribute {:?} not found", &attribute))?;
let all_uvs: &Vec<[f32; 2]> = match &attrs {
VertexAttributeValues::Float32x2(positions) => positions,
_ => bail!("Unexpected types in {:?}", Mesh::ATTRIBUTE_UV_0),
};
let bary = hit.barycentric_coords;
Ok(Vec2::from_array(all_uvs[a]) * bary.x
+ Vec2::from_array(all_uvs[b]) * bary.y
+ Vec2::from_array(all_uvs[c]) * bary.z)
}
fn get_indices(mesh: &Mesh, hit: &RayMeshHit) -> Result<(usize, usize, usize)> {
let i = hit
.triangle_index
.ok_or_eyre("Intersection Index not found")?;
Ok(mesh.indices().map_or_else(
|| (i, i + 1, i + 2),
|indices| match indices {
Indices::U16(indices) => (
indices[i * 3] as usize,
indices[i * 3 + 1] as usize,
indices[i * 3 + 2] as usize,
),
Indices::U32(indices) => (
indices[i * 3] as usize,
indices[i * 3 + 1] as usize,
indices[i * 3 + 2] as usize,
),
},
))
}
```
PS: created a new PR because the old one was coming from and targeting
the wrong branches
10daca0947