Rename varialble for better understanding.

Write some API usage in README.md.

README.md

@@ -79,9 +79,9 @@ Features
 TODO
 ----
 
-* [ ] Read .obj/.mtl from memory.
 * [ ] Fix Python binding.
-* [ ] Unit test codes.
+* [ ] Fix obj_sticker example.
+* [ ] More unit test codes.
 
 License
 -------
@@ -91,6 +91,10 @@ Licensed under MIT license.
 Usage
 -----
 
+`attrib_t` contains single and linear array of vertex data(position, normal and texcoord).
+Each `shape_t` does not contain vertex data but contains array index to `attrib_t`.
+See `loader_example.cc` for more details.
+
 ```c++
 #define TINYOBJLOADER_IMPLEMENTATION // define this in only *one* .cc
 #include "tiny_obj_loader.h"
@@ -111,7 +115,33 @@ if (!ret) {
   exit(1);
 }
 
-// See loader_example.cc for more details.
+// Loop over shapes
+for (size_t s = 0; s < shapes.size(); s++) {
+  // Loop over faces(polygon)
+  size_t index_offset = 0;
+  for (size_t f = 0; f < shapes[i].mesh.num_face_vertices; f++) {
+    int fv = shapes[i].mesh.num_face_vertices[f];
+
+    // Loop over vertices in the face.
+    for (size_t v = 0; v < fv; f++) {
+      // access to vertex
+      tinyobj::index_t idx = shapes[i].mesh.indices[index_offset + v];
+      float vx = attrib.positions[3*idx.vertex_index+0];
+      float vy = attrib.positions[3*idx.vertex_index+1];
+      float vz = attrib.positions[3*idx.vertex_index+2];
+      float nx = attrib.normals[3*idx.normal_index+0];
+      float ny = attrib.normals[3*idx.normal_index+1];
+      float nz = attrib.normals[3*idx.normal_index+2];
+      float tx = attrib.texcoords[2*idx.texcoord_index+0];
+      float ty = attrib.texcoords[2*idx.texcoord_index+1];
+    }
+    index_offset += fv;
+
+    // per-face material
+    shapes[i].mesh.material_ids[f];
+  }
+}
+
 ```
 
 

loader_example.cc

@@ -65,7 +65,7 @@ static void PrintInfo(const tinyobj::attrib_t &attrib, const std::vector<tinyobj
       }
 
       printf("Size of shape[%ld].material_ids: %ld\n", i, shapes[i].mesh.material_ids.size());
-      assert(shapes[i].mesh.material_ids.size() == shapes[i].mesh.num_vertices.size());
+      assert(shapes[i].mesh.material_ids.size() == shapes[i].mesh.num_face_vertices.size());
       for (size_t m = 0; m < shapes[i].mesh.material_ids.size(); m++) {
         printf("  material_id[%ld] = %d\n", m,
           shapes[i].mesh.material_ids[m]);
@@ -73,10 +73,10 @@ static void PrintInfo(const tinyobj::attrib_t &attrib, const std::vector<tinyobj
 
     }
 
-    printf("shape[%ld].num_faces: %ld\n", i, shapes[i].mesh.num_vertices.size());
+    printf("shape[%ld].num_faces: %ld\n", i, shapes[i].mesh.num_face_vertices.size());
-    for (size_t v = 0; v < shapes[i].mesh.num_vertices.size(); v++) {
+    for (size_t v = 0; v < shapes[i].mesh.num_face_vertices.size(); v++) {
-      printf("  num_vertices[%ld] = %ld\n", v,
+      printf("  num_face_vertices[%ld] = %ld\n", v,
-        static_cast<long>(shapes[i].mesh.num_vertices[v]));
+        static_cast<long>(shapes[i].mesh.num_face_vertices[v]));
     }
 
     //printf("shape[%ld].vertices: %ld\n", i, shapes[i].mesh.positions.size());

tests/tester.cc

@@ -65,7 +65,7 @@ static void PrintInfo(const tinyobj::attrib_t &attrib, const std::vector<tinyobj
       }
 
       printf("Size of shape[%ld].material_ids: %ld\n", i, shapes[i].mesh.material_ids.size());
-      assert(shapes[i].mesh.material_ids.size() == shapes[i].mesh.num_vertices.size());
+      assert(shapes[i].mesh.material_ids.size() == shapes[i].mesh.num_face_vertices.size());
       for (size_t m = 0; m < shapes[i].mesh.material_ids.size(); m++) {
         printf("  material_id[%ld] = %d\n", m,
           shapes[i].mesh.material_ids[m]);
@@ -73,10 +73,10 @@ static void PrintInfo(const tinyobj::attrib_t &attrib, const std::vector<tinyobj
 
     }
 
-    printf("shape[%ld].num_faces: %ld\n", i, shapes[i].mesh.num_vertices.size());
+    printf("shape[%ld].num_faces: %ld\n", i, shapes[i].mesh.num_face_vertices.size());
-    for (size_t v = 0; v < shapes[i].mesh.num_vertices.size(); v++) {
+    for (size_t v = 0; v < shapes[i].mesh.num_face_vertices.size(); v++) {
       printf("  num_vertices[%ld] = %ld\n", v,
-        static_cast<long>(shapes[i].mesh.num_vertices[v]));
+        static_cast<long>(shapes[i].mesh.num_face_vertices[v]));
     }
 
     //printf("shape[%ld].vertices: %ld\n", i, shapes[i].mesh.positions.size());

tiny_obj_loader.h

@@ -113,7 +113,7 @@ typedef struct {
 typedef struct {
   std::vector<index_t> indices;
   std::vector<unsigned char>
-      num_vertices;               // The number of vertices per face. Up to 255.
+      num_face_vertices;               // The number of vertices per face. 3 = polygon, 4 = quad, ... Up to 255.
   std::vector<int> material_ids;  // per-face material ID
   std::vector<tag_t> tags;        // SubD tag
 } mesh_t;
@@ -604,7 +604,7 @@ static bool exportFaceGroupToShape(
         shape->mesh.indices.push_back(idx1);
         shape->mesh.indices.push_back(idx2);
 
-        shape->mesh.num_vertices.push_back(3);
+        shape->mesh.num_face_vertices.push_back(3);
         shape->mesh.material_ids.push_back(material_id);
       }
     } else {
@@ -615,7 +615,7 @@ static bool exportFaceGroupToShape(
         idx.texcoord_index = face[k].vt_idx;
       }
 
-      shape->mesh.num_vertices.push_back(static_cast<unsigned char>(npolys));
+      shape->mesh.num_face_vertices.push_back(static_cast<unsigned char>(npolys));
       shape->mesh.material_ids.push_back(material_id);  // per face
     }
   }