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Fix loading non-TriangleList meshes without normals in gltf loader (#4376)

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# Objective
Make it so that loading in a mesh without normals that is not a `TriangleList` succeeds.

## Solution
Flat normals can only be calculated on a mesh made of triangles.
Check whether the mesh is a `TriangleList` before trying to compute missing normals.

## Additional changes
The panic condition in `duplicate_vertices` did not make sense to me. I moved it to `compute_flat_normals` where the algorithm would produce incorrect results if the mesh is not a `TriangleList`.

Co-authored-by: devil-ira <justthecooldude@gmail.com>
This commit is contained in:
devil ira 2022-03-31 20:43:01 +00:00
parent aca7fc1854
commit 48ac955afd
2 changed files with 11 additions and 10 deletions
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4
crates/bevy_gltf/src/loader.rs
View file

@ -268,7 +268,9 @@ async fn load_gltf<'a, 'b>(
mesh.set_indices(Some(Indices::U32(indices.into_u32().collect())));
};
if mesh.attribute(Mesh::ATTRIBUTE_NORMAL).is_none() {
if mesh.attribute(Mesh::ATTRIBUTE_NORMAL).is_none()
&& matches!(mesh.primitive_topology(), PrimitiveTopology::TriangleList)
{
let vertex_count_before = mesh.count_vertices();
mesh.duplicate_vertices();
mesh.compute_flat_normals();

17
crates/bevy_render/src/mesh/mesh/mod.rs
View file

@ -252,23 +252,16 @@ impl Mesh {
///
/// This can dramatically increase the vertex count, so make sure this is what you want.
/// Does nothing if no [Indices] are set.
///
/// # Panics
/// If the mesh has any other topology than [`PrimitiveTopology::TriangleList`].
pub fn duplicate_vertices(&mut self) {
fn duplicate<T: Copy>(values: &[T], indices: impl Iterator<Item = usize>) -> Vec<T> {
indices.map(|i| values[i]).collect()
}
assert!(
matches!(self.primitive_topology, PrimitiveTopology::TriangleList),
"can only duplicate vertices for `TriangleList`s"
);
let indices = match self.indices.take() {
Some(indices) => indices,
None => return,
};
for attributes in self.attributes.values_mut() {
let indices = indices.iter();
match &mut attributes.values {
@ -307,11 +300,17 @@ impl Mesh {
/// Calculates the [`Mesh::ATTRIBUTE_NORMAL`] of a mesh.
///
/// # Panics
/// Panics if [`Indices`] are set or [`Mesh::ATTRIBUTE_POSITION`] is not of type `float3`.
/// Panics if [`Indices`] are set or [`Mesh::ATTRIBUTE_POSITION`] is not of type `float3` or
/// if the mesh has any other topology than [`PrimitiveTopology::TriangleList`].
/// Consider calling [`Mesh::duplicate_vertices`] or export your mesh with normal attributes.
pub fn compute_flat_normals(&mut self) {
assert!(self.indices().is_none(), "`compute_flat_normals` can't work on indexed geometry. Consider calling `Mesh::duplicate_vertices`.");
assert!(
matches!(self.primitive_topology, PrimitiveTopology::TriangleList),
"`compute_flat_normals` can only work on `TriangleList`s"
);
let positions = self
.attribute(Mesh::ATTRIBUTE_POSITION)
.unwrap()