From e4c33b5c5fb51668be59116c5a3a172154c1d0d1 Mon Sep 17 00:00:00 2001
From: Sam <scr145@student.bham.ac.uk>
Date: Thu, 28 Dec 2023 00:28:23 +0000
Subject: [PATCH] fixed panic on loading obj without normals

---
 .../tutorial9-models/src/resources.rs         | 42 ++++++++++++-------
 docs/beginner/tutorial9-models/README.md      | 40 ++++++++++++------
 2 files changed, 55 insertions(+), 27 deletions(-)

diff --git a/code/beginner/tutorial9-models/src/resources.rs b/code/beginner/tutorial9-models/src/resources.rs
index fd8738aae..cc5fa73b8 100644
--- a/code/beginner/tutorial9-models/src/resources.rs
+++ b/code/beginner/tutorial9-models/src/resources.rs
@@ -118,20 +118,34 @@ pub async fn load_model(
         .into_iter()
         .map(|m| {
             let vertices = (0..m.mesh.positions.len() / 3)
-                .map(|i| 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: [
-                        m.mesh.normals[i * 3],
-                        m.mesh.normals[i * 3 + 1],
-                        m.mesh.normals[i * 3 + 2],
-                    ],
-                })
-                .collect::<Vec<_>>();
+            .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],
+                            m.mesh.positions[i * 3 + 2],
+                        ],
+                        tex_coords: [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]],
+                        normal: [
+                            m.mesh.normals[i * 3],
+                            m.mesh.normals[i * 3 + 1],
+                            m.mesh.normals[i * 3 + 2],
+                        ],
+                    }
+                }
+            })
+            .collect::<Vec<_>>();
 
             let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                 label: Some(&format!("{:?} Vertex Buffer", file_name)),
diff --git a/docs/beginner/tutorial9-models/README.md b/docs/beginner/tutorial9-models/README.md
index f12566329..ebc7b2793 100644
--- a/docs/beginner/tutorial9-models/README.md
+++ b/docs/beginner/tutorial9-models/README.md
@@ -341,19 +341,33 @@ pub async fn load_model(
     let meshes = models
         .into_iter()
         .map(|m| {
-            let vertices = (0..m.mesh.positions.len() / 3)
-                .map(|i| 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: [
-                        m.mesh.normals[i * 3],
-                        m.mesh.normals[i * 3 + 1],
-                        m.mesh.normals[i * 3 + 2],
-                    ],
+                let vertices = (0..m.mesh.positions.len() / 3)
+                .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],
+                                m.mesh.positions[i * 3 + 2],
+                            ],
+                            tex_coords: [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]],
+                            normal: [
+                                m.mesh.normals[i * 3],
+                                m.mesh.normals[i * 3 + 1],
+                                m.mesh.normals[i * 3 + 2],
+                            ],
+                        }
+                    }
                 })
                 .collect::<Vec<_>>();