fixed parse_object by implementing custom parsers

std::setlocale also change the parsing of floats with std::stof. It is also more
future proof to use a parser specific to Wavefront .obj files.

1 files changed, 80 insertions, 20 deletions

diff --git a/src/obj_parser.cpp b/src/obj_parser.cpp
index 7791678..ad71935 100644
--- a/src/obj_parser.cpp
+++ b/src/obj_parser.cpp
@@ -27,6 +27,66 @@ std::vector<std::string> split(const std::string& s, char sep) {
     return res;
 }
 
+float parse_float(const std::string& s) {
+    std::string::size_type ind = 0;
+    bool positive = true;
+    while (ind < s.length() && (s[ind] == '+' || s[ind] == '-'))
+        if (s[ind++] == '-')
+            positive = !positive;
+
+    // improve error checking
+    if (ind == s.length())
+        return 0.f;
+
+    int n = 0;
+    while (ind < s.length() && s[ind] >= '0' && s[ind] <= '9')
+        n = n * 10 + static_cast<int>(s[ind++]) - static_cast<int>('0');
+
+    if (ind == s.length())
+        return (positive ? 1.f : -1.f) * static_cast<float>(n);
+
+    // improve error checking
+    if (s[ind] != '.')
+        return 0.f;
+
+    ind++;
+
+    float decimal_part = 0.f;
+    float decimal_fac = .1f;
+    while (ind < s.length() && s[ind] >= '0' && s[ind] <= '9') {
+        decimal_part += decimal_fac * static_cast<float>(static_cast<int>(s[ind++]) - static_cast<int>('0'));
+        decimal_fac *= .1f;
+    }
+
+    // improve error checking
+    if (ind != s.length())
+        return 0.f;
+
+    return (positive ? 1.f : -1.f) * (static_cast<float>(n) + decimal_part);
+}
+
+float parse_int(const std::string& s) {
+    std::string::size_type ind = 0;
+    bool positive = true;
+    while (ind < s.length() && (s[ind] == '+' || s[ind] == '-'))
+        if (s[ind++] == '-')
+            positive = !positive;
+
+    // improve error checking
+    if (ind == s.length())
+        return 0.f;
+
+    int n = 0;
+    while (ind < s.length() && s[ind] >= '0' && s[ind] <= '9')
+        n = n * 10 + static_cast<int>(s[ind++]) - static_cast<int>('0');
+
+    // improve error checking
+    if (ind != s.length())
+        return 0.f;
+
+    return (positive ? 1.f : -1.f) * n;
+}
+
 }
 
 o3d::Mesh parse_object(const std::string& obj_path) {
@@ -38,40 +98,40 @@ o3d::Mesh parse_object(const std::string& obj_path) {
         if (line.length() == 0 || line[0] == '#')
             continue;
         if (line.rfind("o ", 0) == 0) {
-            std::cout << "Object: " << line.substr(2) << std::endl;
+            // std::cout << "Object: " << line.substr(2) << std::endl;
         } else if (line.rfind("v ", 0) == 0) {
             auto s_coords = split(line.substr(2), ' ');
-            math::Vector3 v{std::stof(s_coords[0]), std::stof(s_coords[1]), std::stof(s_coords[2])};
-            std::cout << "Vertex x: " << v.x << " y: " << v.y << " z: " << v.z << std::endl;
+            math::Vector4 v{parse_float(s_coords[0]), parse_float(s_coords[1]), parse_float(s_coords[2]), 1.f};
+            // std::cout << "Vertex x: " << v.x << " y: " << v.y << " z: " << v.z << std::endl;
             mesh.vertices.push_back(v);
         } else if (line.rfind("vn ", 0) == 0) {
             auto s_coords = split(line.substr(3), ' ');
-            math::Vector3 vn{std::stof(s_coords[0]), std::stof(s_coords[1]), std::stof(s_coords[2])};
-            std::cout << "Vertex normal x: " << vn.x << " y: " << vn.y << " z: " << vn.z << std::endl;
+            math::Vector3 vn{parse_float(s_coords[0]), parse_float(s_coords[1]), parse_float(s_coords[2])};
+            // std::cout << "Vertex normal x: " << vn.x << " y: " << vn.y << " z: " << vn.z << std::endl;
             mesh.normals.push_back(vn);
         } else if (line.rfind("s ", 0) == 0) {
-            auto smooth = false;
-            auto s_smooth = line.substr(2);
-            if (s_smooth == "0" || s_smooth == "off") {
-                smooth = false;
-            } else if (s_smooth == "1" || s_smooth == "on") {
-                smooth = true;
-            }
-            std::cout << "Smooth: " << std::boolalpha << smooth << std::endl;
+            // auto smooth = false;
+            // auto s_smooth = line.substr(2);
+            // if (s_smooth == "0" || s_smooth == "off") {
+            //     smooth = false;
+            // } else if (s_smooth == "1" || s_smooth == "on") {
+            //     smooth = true;
+            // }
+            // std::cout << "Smooth: " << std::boolalpha << smooth << std::endl;
         } else if (line.rfind("f ", 0) == 0) {
             std::array<std::array<std::size_t, 3>, 3> indices;
             auto line_split = split(line.substr(2), ' ');
             for (int i = 0; i < 3; i++) {
                 auto indices_s_group = split(line_split[i], '/');
-                indices[i][0] = std::stoi(indices_s_group[0]) - 1;
-                indices[i][1] = std::stoi(indices_s_group[2]) - 1;
+                indices[i][0] = parse_int(indices_s_group[0]) - 1;
+                indices[i][1] = parse_int(indices_s_group[2]) - 1;
                 indices[i][2] = 0;
             }
-            std::cout << "Face:"
-                << " 1: vertex: " << indices[0][0] << " normal: " << indices[0][1]
-                << " 2: vertex: " << indices[1][0] << " normal: " << indices[1][1]
-                << " 3: vertex: " << indices[2][0] << " normal: " << indices[2][1]
-                << std::endl;
+            // std::cout << "Face:"
+            //     << " 1: vertex: " << indices[0][0] << " normal: " << indices[0][1]
+            //     << " 2: vertex: " << indices[1][0] << " normal: " << indices[1][1]
+            //     << " 3: vertex: " << indices[2][0] << " normal: " << indices[2][1]
+            //     << std::endl;
             mesh.indices.push_back(indices);
         }
     }