Add initial iter_meshes()

src/mesh/group.rs

@@ -80,4 +80,13 @@ impl MeshGroup {
 
         Ok((handle, copies))
     }
+
+    /// Gets a [MeshHandle's][MeshHandle] [MeshAlloc].
+    pub fn get_alloc(&self, handle: &MeshHandle) -> Option<&MeshAlloc> {
+        if handle.group != self.id {
+            None
+        } else {
+            self.meshes.get(handle.sub)
+        }
+    }
 }

src/mesh/mod.rs

@@ -142,4 +142,37 @@ impl MeshPool {
         self.staging.queue_copies(copies);
         Ok(handle)
     }
+
+    pub fn iter_meshes<T: HasMeshHandle>(
+        &self,
+        meshes: impl IntoIterator<Item = T>,
+    ) -> Vec<(&MeshGroup, Vec<(&MeshAlloc, T)>)> {
+        let group_num = self.groups.len();
+        let mut by_group = Vec::with_capacity(group_num);
+        for index in 0..group_num {
+            let group = self.groups.get(index);
+            let meshes = Vec::new();
+            by_group.push((group, meshes));
+        }
+
+        for mesh in meshes {
+            let handle = mesh.get_mesh_handle();
+            let (group, meshes) = match by_group.get_mut(handle.group) {
+                Some((Some(group), meshes)) => (group, meshes),
+                _ => continue,
+            };
+
+            let alloc = match group.get_alloc(handle) {
+                Some(alloc) => alloc,
+                None => continue, // TODO err out on invalid handle?
+            };
+
+            meshes.push((alloc, mesh));
+        }
+
+        by_group
+            .into_iter()
+            .filter_map(|(group, meshes)| group.map(|group| (group, meshes)))
+            .collect()
+    }
 }