From 35adad655690e5bcef417ccba68c925df9415a63 Mon Sep 17 00:00:00 2001
From: Carter Anderson <mcanders1@gmail.com>
Date: Fri, 15 May 2020 17:22:45 -0700
Subject: [PATCH] Async mesh loading works

---
 crates/bevy_render/src/mesh.rs | 50 ++++++++++++++++++----------------
 examples/3d/load_model.rs      |  3 +-
 2 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/crates/bevy_render/src/mesh.rs b/crates/bevy_render/src/mesh.rs
index 152a517056..6bb3ed422c 100644
--- a/crates/bevy_render/src/mesh.rs
+++ b/crates/bevy_render/src/mesh.rs
@@ -346,30 +346,34 @@ fn setup_mesh_resource(
             render_resources.get_asset_resource(handle, INDEX_BUFFER_ASSET_INDEX),
         )
     } else {
-        let mesh_asset = meshes.get(&handle).unwrap();
-        let vertex_bytes = mesh_asset
-            .get_vertex_buffer_bytes(&vertex_buffer_descriptor)
-            .unwrap();
-        // TODO: use a staging buffer here
-        let vertex_buffer = render_resources.create_buffer_with_data(
-            BufferInfo {
-                buffer_usage: BufferUsage::VERTEX,
-                ..Default::default()
-            },
-            &vertex_bytes,
-        );
-        let index_bytes = mesh_asset.get_index_buffer_bytes(index_format).unwrap();
-        let index_buffer = render_resources.create_buffer_with_data(
-            BufferInfo {
-                buffer_usage: BufferUsage::INDEX,
-                ..Default::default()
-            },
-            &index_bytes,
-        );
+        if let Some(mesh_asset) = meshes.get(&handle) {
+            let vertex_bytes = mesh_asset
+                .get_vertex_buffer_bytes(&vertex_buffer_descriptor)
+                .unwrap();
+            // TODO: use a staging buffer here
+            let vertex_buffer = render_resources.create_buffer_with_data(
+                BufferInfo {
+                    buffer_usage: BufferUsage::VERTEX,
+                    ..Default::default()
+                },
+                &vertex_bytes,
+            );
+            let index_bytes = mesh_asset.get_index_buffer_bytes(index_format).unwrap();
+            let index_buffer = render_resources.create_buffer_with_data(
+                BufferInfo {
+                    buffer_usage: BufferUsage::INDEX,
+                    ..Default::default()
+                },
+                &index_bytes,
+            );
 
-        render_resources.set_asset_resource(handle, vertex_buffer, VERTEX_BUFFER_ASSET_INDEX);
-        render_resources.set_asset_resource(handle, index_buffer, INDEX_BUFFER_ASSET_INDEX);
-        (vertex_buffer, Some(index_buffer))
+            render_resources.set_asset_resource(handle, vertex_buffer, VERTEX_BUFFER_ASSET_INDEX);
+            render_resources.set_asset_resource(handle, index_buffer, INDEX_BUFFER_ASSET_INDEX);
+            (vertex_buffer, Some(index_buffer))
+        } else {
+            // mesh doesn't exist. it probably hasn't loaded yet
+            return;
+        }
     };
 
     render_resource_assignments.set_vertex_buffer("Vertex", vertex_buffer, index_buffer);
diff --git a/examples/3d/load_model.rs b/examples/3d/load_model.rs
index 8e4f6f60b9..47a05c96d9 100644
--- a/examples/3d/load_model.rs
+++ b/examples/3d/load_model.rs
@@ -11,12 +11,11 @@ fn main() {
 fn setup(
     command_buffer: &mut CommandBuffer,
     asset_server: ResMut<AssetServer>,
-    mut meshes: ResMut<Assets<Mesh>>,
     mut materials: ResMut<Assets<StandardMaterial>>,
 ) {
     // load the mesh
     let mesh_handle = asset_server
-        .load_sync(&mut meshes, "assets/models/monkey/Monkey.gltf")
+        .load("assets/models/monkey/Monkey.gltf")
         .unwrap();
 
     // create a material for the mesh