Update example code in README. (#301)

1 files changed, 42 insertions, 24 deletions

diff --git a/README.md b/README.md
index 1fda8ae..ce5ab1b 100644
--- a/README.md
+++ b/README.md
@@ -274,24 +274,33 @@ 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[s].mesh.num_face_vertices.size(); f++) {
-    int fv = shapes[s].mesh.num_face_vertices[f];
+    size_t fv = size_t(shapes[s].mesh.num_face_vertices[f]);
 
     // Loop over vertices in the face.
     for (size_t v = 0; v < fv; v++) {
       // access to vertex
       tinyobj::index_t idx = shapes[s].mesh.indices[index_offset + v];
-      tinyobj::real_t vx = attrib.vertices[3*idx.vertex_index+0];
-      tinyobj::real_t vy = attrib.vertices[3*idx.vertex_index+1];
-      tinyobj::real_t vz = attrib.vertices[3*idx.vertex_index+2];
-      tinyobj::real_t nx = attrib.normals[3*idx.normal_index+0];
-      tinyobj::real_t ny = attrib.normals[3*idx.normal_index+1];
-      tinyobj::real_t nz = attrib.normals[3*idx.normal_index+2];
-      tinyobj::real_t tx = attrib.texcoords[2*idx.texcoord_index+0];
-      tinyobj::real_t ty = attrib.texcoords[2*idx.texcoord_index+1];
+
+      tinyobj::real_t vx = attrib.vertices[3*size_t(idx.vertex_index)+0];
+      tinyobj::real_t vy = attrib.vertices[3*size_t(idx.vertex_index)+1];
+      tinyobj::real_t vz = attrib.vertices[3*size_t(idx.vertex_index)+2];
+
+      // Check if `normal_index` is zero or positive. negative = no normal data
+      if (idx.normal_index >= 0) {
+        tinyobj::real_t nx = attrib.normals[3*size_t(idx.normal_index)+0];
+        tinyobj::real_t ny = attrib.normals[3*size_t(idx.normal_index)+1];
+        tinyobj::real_t nz = attrib.normals[3*size_t(idx.normal_index)+2];
+      }
+
+      // Check if `texcoord_index` is zero or positive. negative = no texcoord data
+      if (idx.texcoord_index >= 0) {
+        tinyobj::real_t tx = attrib.texcoords[2*size_t(idx.texcoord_index)+0];
+        tinyobj::real_t ty = attrib.texcoords[2*size_t(idx.texcoord_index)+1];
+      }
       // Optional: vertex colors
-      // tinyobj::real_t red = attrib.colors[3*idx.vertex_index+0];
-      // tinyobj::real_t green = attrib.colors[3*idx.vertex_index+1];
-      // tinyobj::real_t blue = attrib.colors[3*idx.vertex_index+2];
+      // tinyobj::real_t red   = attrib.colors[3*size_t(idx.vertex_index)+0];
+      // tinyobj::real_t green = attrib.colors[3*size_t(idx.vertex_index)+1];
+      // tinyobj::real_t blue  = attrib.colors[3*size_t(idx.vertex_index)+2];
     }
     index_offset += fv;
 
@@ -335,24 +344,33 @@ 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[s].mesh.num_face_vertices.size(); f++) {
-    int fv = shapes[s].mesh.num_face_vertices[f];
+    size_t fv = size_t(shapes[s].mesh.num_face_vertices[f]);
 
     // Loop over vertices in the face.
     for (size_t v = 0; v < fv; v++) {
       // access to vertex
       tinyobj::index_t idx = shapes[s].mesh.indices[index_offset + v];
-      tinyobj::real_t vx = attrib.vertices[3*idx.vertex_index+0];
-      tinyobj::real_t vy = attrib.vertices[3*idx.vertex_index+1];
-      tinyobj::real_t vz = attrib.vertices[3*idx.vertex_index+2];
-      tinyobj::real_t nx = attrib.normals[3*idx.normal_index+0];
-      tinyobj::real_t ny = attrib.normals[3*idx.normal_index+1];
-      tinyobj::real_t nz = attrib.normals[3*idx.normal_index+2];
-      tinyobj::real_t tx = attrib.texcoords[2*idx.texcoord_index+0];
-      tinyobj::real_t ty = attrib.texcoords[2*idx.texcoord_index+1];
+      tinyobj::real_t vx = attrib.vertices[3*size_t(idx.vertex_index)+0];
+      tinyobj::real_t vy = attrib.vertices[3*size_t(idx.vertex_index)+1];
+      tinyobj::real_t vz = attrib.vertices[3*size_t(idx.vertex_index)+2];
+ 
+      // Check if `normal_index` is zero or positive. negative = no normal data
+      if (idx.normal_index >= 0) {
+        tinyobj::real_t nx = attrib.normals[3*size_t(idx.normal_index)+0];
+        tinyobj::real_t ny = attrib.normals[3*size_t(idx.normal_index)+1];
+        tinyobj::real_t nz = attrib.normals[3*size_t(idx.normal_index)+2];
+      }
+
+      // Check if `texcoord_index` is zero or positive. negative = no texcoord data
+      if (idx.texcoord_index >= 0) {
+        tinyobj::real_t tx = attrib.texcoords[2*size_t(idx.texcoord_index)+0];
+        tinyobj::real_t ty = attrib.texcoords[2*size_t(idx.texcoord_index)+1];
+      }
+
       // Optional: vertex colors
-      // tinyobj::real_t red = attrib.colors[3*idx.vertex_index+0];
-      // tinyobj::real_t green = attrib.colors[3*idx.vertex_index+1];
-      // tinyobj::real_t blue = attrib.colors[3*idx.vertex_index+2];
+      // tinyobj::real_t red   = attrib.colors[3*size_t(idx.vertex_index)+0];
+      // tinyobj::real_t green = attrib.colors[3*size_t(idx.vertex_index)+1];
+      // tinyobj::real_t blue  = attrib.colors[3*size_t(idx.vertex_index)+2];
     }
     index_offset += fv;