fixed panic on loading obj without normals

code/beginner/tutorial9-models/src/resources.rs

@@ -118,7 +118,19 @@ pub async fn load_model(
         .into_iter()
         .map(|m| {
             let vertices = (0..m.mesh.positions.len() / 3)
-                .map(|i| model::ModelVertex {
+            .map(|i| {
+                if m.mesh.normals.is_empty(){
+                    model::ModelVertex {
+                        position: [
+                            m.mesh.positions[i * 3],
+                            m.mesh.positions[i * 3 + 1],
+                            m.mesh.positions[i * 3 + 2],
+                        ],
+                        tex_coords: [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]],
+                        normal: [0.0, 0.0, 0.0],
+                    }
+                }else{
+                    model::ModelVertex {
                         position: [
                             m.mesh.positions[i * 3],
                             m.mesh.positions[i * 3 + 1],
@@ -130,6 +142,8 @@ pub async fn load_model(
                             m.mesh.normals[i * 3 + 1],
                             m.mesh.normals[i * 3 + 2],
                         ],
+                    }
+                }
             })
             .collect::<Vec<_>>();
 

docs/beginner/tutorial9-models/README.md

@@ -342,7 +342,19 @@ pub async fn load_model(
         .into_iter()
         .map(|m| {
                 let vertices = (0..m.mesh.positions.len() / 3)
-                .map(|i| model::ModelVertex {
+                .map(|i| {
+                    if m.mesh.normals.is_empty(){
+                        model::ModelVertex {
+                            position: [
+                                m.mesh.positions[i * 3],
+                                m.mesh.positions[i * 3 + 1],
+                                m.mesh.positions[i * 3 + 2],
+                            ],
+                            tex_coords: [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]],
+                            normal: [0.0, 0.0, 0.0],
+                        }
+                    }else{
+                        model::ModelVertex {
                             position: [
                                 m.mesh.positions[i * 3],
                                 m.mesh.positions[i * 3 + 1],
@@ -354,6 +366,8 @@ pub async fn load_model(
                                 m.mesh.normals[i * 3 + 1],
                                 m.mesh.normals[i * 3 + 2],
                             ],
+                        }
+                    }
                 })
                 .collect::<Vec<_>>();