From 7fb8af73bfde77edd0e71432030070c9c9a920e1 Mon Sep 17 00:00:00 2001
From: Pedro Pereira <pmh.pereira@gmail.com>
Date: Fri, 5 Nov 2021 01:08:29 +0000
Subject: [PATCH] 3DFileViewer: Add vertex normal parsing to WavefrontOBJLoader

This change allows us to parse vertex-normal lines "vn x y z"
and map them to the correct index on face lines ("f v1/vt1/vn1").
---
 Userland/Applications/3DFileViewer/Common.h   |  5 +++
 .../3DFileViewer/WavefrontOBJLoader.cpp       | 42 ++++++++++++++++---
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/Userland/Applications/3DFileViewer/Common.h b/Userland/Applications/3DFileViewer/Common.h
index 781519dcae..c84c6cf086 100644
--- a/Userland/Applications/3DFileViewer/Common.h
+++ b/Userland/Applications/3DFileViewer/Common.h
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
  * Copyright (c) 2021, Mathieu Gaillard <gaillard.mathieu.39@gmail.com>
+ * Copyright (c) 2021, Pedro Pereira <pmh.pereira@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -30,4 +31,8 @@ struct Triangle {
     GLuint tex_coord_index0;
     GLuint tex_coord_index1;
     GLuint tex_coord_index2;
+
+    GLuint normal_index0;
+    GLuint normal_index1;
+    GLuint normal_index2;
 };
diff --git a/Userland/Applications/3DFileViewer/WavefrontOBJLoader.cpp b/Userland/Applications/3DFileViewer/WavefrontOBJLoader.cpp
index 83b23c9782..bb881c333a 100644
--- a/Userland/Applications/3DFileViewer/WavefrontOBJLoader.cpp
+++ b/Userland/Applications/3DFileViewer/WavefrontOBJLoader.cpp
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
  * Copyright (c) 2021, Mathieu Gaillard <gaillard.mathieu.39@gmail.com>
+ * Copyright (c) 2021, Pedro Pereira <pmh.pereira@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -12,6 +13,7 @@
 RefPtr<Mesh> WavefrontOBJLoader::load(Core::File& file)
 {
     Vector<Vertex> vertices;
+    Vector<Vertex> normals;
     Vector<TexCoord> tex_coords;
     Vector<Triangle> triangles;
 
@@ -39,8 +41,17 @@ RefPtr<Mesh> WavefrontOBJLoader::load(Core::File& file)
             continue;
         }
 
-        // FIXME: Parse texture coordinates and vertex normals
         if (object_line.starts_with("vn")) {
+            auto normal_line = object_line.split_view(' ');
+            if (normal_line.size() != 4) {
+                dbgln("Wavefront: Malformed vertex normal line. Aborting.");
+                return nullptr;
+            }
+
+            normals.append({ static_cast<GLfloat>(atof(String(normal_line.at(1)).characters())),
+                static_cast<GLfloat>(atof(String(normal_line.at(2)).characters())),
+                static_cast<GLfloat>(atof(String(normal_line.at(3)).characters())) });
+
             continue;
         }
 
@@ -55,9 +66,12 @@ RefPtr<Mesh> WavefrontOBJLoader::load(Core::File& file)
             vertices.append({ static_cast<GLfloat>(atof(String(vertex_line.at(1)).characters())),
                 static_cast<GLfloat>(atof(String(vertex_line.at(2)).characters())),
                 static_cast<GLfloat>(atof(String(vertex_line.at(3)).characters())) });
+
+            continue;
         }
+
         // This line describes a face (a collection of 3 vertices, aka a triangle)
-        else if (object_line.starts_with("f")) {
+        if (object_line.starts_with("f")) {
             auto face_line = object_line.split_view(' ');
             if (face_line.size() != 4) {
                 dbgln("Wavefront: Malformed face line. Aborting.");
@@ -66,10 +80,18 @@ RefPtr<Mesh> WavefrontOBJLoader::load(Core::File& file)
 
             GLuint vert_index[3];
             GLuint tex_coord_index[3];
+            GLuint normal_index[3];
             if (object_line.contains("/")) {
                 for (int i = 1; i <= 3; ++i) {
-                    vert_index[i - 1] = face_line.at(i).split_view("/").at(0).to_uint().value_or(1);
-                    tex_coord_index[i - 1] = face_line.at(i).split_view("/").at(1).to_uint().value_or(1);
+                    auto vertex_data = face_line.at(i).split_view("/", true);
+
+                    vert_index[i - 1] = vertex_data.at(0).to_uint().value_or(1);
+                    tex_coord_index[i - 1] = vertex_data.at(1).to_uint().value_or(1);
+
+                    if (vertex_data.size() == 3)
+                        normal_index[i - 1] = vertex_data.at(2).to_uint().value_or(1);
+                    else
+                        normal_index[i - 1] = 1;
                 }
             } else {
                 vert_index[0] = (face_line.at(1).to_uint().value_or(1));
@@ -78,16 +100,24 @@ RefPtr<Mesh> WavefrontOBJLoader::load(Core::File& file)
                 tex_coord_index[0] = 0;
                 tex_coord_index[1] = 0;
                 tex_coord_index[2] = 0;
+                normal_index[0] = 0;
+                normal_index[1] = 0;
+                normal_index[2] = 0;
             }
 
             // Create a new triangle
             triangles.append(
-                { vert_index[0] - 1,
+                {
+                    vert_index[0] - 1,
                     vert_index[1] - 1,
                     vert_index[2] - 1,
                     tex_coord_index[0] - 1,
                     tex_coord_index[1] - 1,
-                    tex_coord_index[2] - 1 });
+                    tex_coord_index[2] - 1,
+                    normal_index[0] - 1,
+                    normal_index[1] - 1,
+                    normal_index[2] - 1,
+                });
         }
     }