From 363779f80918fabcdbc09ca4b4b0ee417de1a453 Mon Sep 17 00:00:00 2001
From: Muaz Ahmad <m.ahmed_2000@hotmail.com>
Date: Wed, 3 May 2023 14:39:35 +0500
Subject: [PATCH] Added .obj loader

---
 obj.cpp        | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 obj.h          | 10 ++++++----
 opglwidget.cpp |  1 +
 3 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/obj.cpp b/obj.cpp
index 14cd47e..e449a7d 100644
--- a/obj.cpp
+++ b/obj.cpp
@@ -3,6 +3,7 @@
 #include <vector>
 #include <string>
 #include <cstring>
+#include <regex>
 
 void ObjectLoader::load_mtl(string filename) {
 	string tmp;
@@ -43,6 +44,51 @@ void ObjectLoader::load_obj(string filename) {
 	string tmp;
 	ifstream f(filename);
 	while (getline(f, tmp)) {
+		Material* mtl_ptr;
+		if (tmp[0] == 'v') {
+			float* target_list;
+			switch (tmp[1]) {
+				case ' ':
+					vertices.push_back(*(new Vertex));
+					target_list = vertices.back().pos;
+					break;
+				case 'n':
+					normals.push_back(*(new Normal));
+					target_list = normals.back().dir;
+					break;
+				default:
+					continue;
+			};
+			char delim = ' ';
+			char *token = strtok(const_cast<char*>(tmp.c_str()), &delim);
+			for (int i = 0; i < 3; i++) {
+				token = strtok(NULL, &delim);
+				target_list[i] = atof(token);
+			};
 
-	}
-}
+		} else if (tmp.rfind("usemtl", 0) == 0) {
+			mtl_ptr = get_mtl_ptr(tmp.substr(tmp.find(' ') + 1));
+		} else if (tmp[0] == 'f') {
+			faces.push_back(*(new Face));
+			faces.back().mtl = mtl_ptr;
+			regex re("f (\\d*)//(\\d*) (\\d*)//(\\d*) (\\d*)//(\\d*)");
+			smatch match;
+			regex_search(tmp, match, re);
+			for (int i = 1; i < 7; i++) {
+				if (i % 2 == 0) {
+					faces.back().normals.push_back(&(normals[stoi(match.str(i))]));
+				} else {
+					faces.back().vertices.push_back(&(vertices[stoi(match.str(i))]));
+				};
+			};
+		};
+	};
+};
+
+Material*  ObjectLoader::get_mtl_ptr(string mtl_name) {
+	for (int i = 0; i < mtls.size(); i++) {
+		if (mtls[i].name == mtl_name) {
+			return &(mtls[i]);
+		};
+	};
+};
diff --git a/obj.h b/obj.h
index f2a3ac9..2a8e0c9 100644
--- a/obj.h
+++ b/obj.h
@@ -6,7 +6,7 @@ struct Vertex {
 };
 
 struct Normal {
-	float pos[3];
+	float dir[3];
 };
 
 struct Material {
@@ -18,9 +18,9 @@ struct Material {
 };
 
 struct Face {
-	vector<Vertex> vertices;
-	Normal normal;
-	Material mtl;
+	vector<Vertex*> vertices;
+	vector<Normal*> normals;
+	Material* mtl;
 };
 
 class ObjectLoader 
@@ -32,6 +32,8 @@ public:
 	vector<Face> faces;
 
 protected:
+	Material* get_mtl_ptr(string mtl_name);
+
 	vector<Vertex> vertices;
 	vector<Normal> normals;
 	vector<Material> mtls;
diff --git a/opglwidget.cpp b/opglwidget.cpp
index 9e137bd..f62c61f 100644
--- a/opglwidget.cpp
+++ b/opglwidget.cpp
@@ -24,6 +24,7 @@ void OPGLWidget::initializeGL() {
 
 	ObjectLoader obj;
 	obj.load_mtl("untitled.mtl");
+	obj.load_obj("untitled.obj");
 }
 
 void OPGLWidget::paintGL() {