From 039d4a6c54f7650a55b53a2fd68c38765867ad80 Mon Sep 17 00:00:00 2001
From: Syoyo Fujita <syoyo@lighttransport.com>
Date: Tue, 18 Oct 2016 17:33:28 +0900
Subject: [PATCH] Fix a shape is lost if obj ends with a 'usemtl'. Fixes #104

---
 models/usemtl-issue-104.obj | 30 ++++++++++++++++++++++++++++++
 tests/tester.cc             | 16 ++++++++++++++++
 tiny_obj_loader.h           | 11 +++++++++--
 3 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 models/usemtl-issue-104.obj

diff --git a/models/usemtl-issue-104.obj b/models/usemtl-issue-104.obj
new file mode 100644
index 0000000..5183676
--- /dev/null
+++ b/models/usemtl-issue-104.obj
@@ -0,0 +1,30 @@
+# cornell_box.obj and cornell_box.mtl are grabbed from Intel's embree project.
+# original cornell box data
+  # comment
+
+# empty line including some space
+   
+
+mtllib cornell_box.mtl
+
+o floor
+v 552.8 0.0   0.0
+v 0.0   0.0   0.0
+v 0.0   0.0 559.2
+v 549.6 0.0 559.2
+
+v 130.0 0.0  65.0
+v  82.0 0.0 225.0
+v 240.0 0.0 272.0
+v 290.0 0.0 114.0
+
+v 423.0 0.0 247.0
+v 265.0 0.0 296.0
+v 314.0 0.0 456.0
+v 472.0 0.0 406.0
+
+f 1 2 3 4 
+f 8 7 6 5
+f 12 11 10 9
+
+usemtl white
diff --git a/tests/tester.cc b/tests/tester.cc
index 5573bb6..f38238d 100644
--- a/tests/tester.cc
+++ b/tests/tester.cc
@@ -402,6 +402,7 @@ TEST_CASE("transmittance_filter_Tf", "[Issue95-Tf]") {
   REQUIRE(0.2 == Approx(materials[0].transmittance[1]));
   REQUIRE(0.3 == Approx(materials[0].transmittance[2]));
 }
+
 TEST_CASE("transmittance_filter_Kt", "[Issue95-Kt]") {
   tinyobj::attrib_t attrib;
   std::vector<tinyobj::shape_t> shapes;
@@ -420,6 +421,21 @@ TEST_CASE("transmittance_filter_Kt", "[Issue95-Kt]") {
   REQUIRE(0.3 == Approx(materials[0].transmittance[2]));
 }
 
+TEST_CASE("usemtl_at_last_line", "[Issue104]") {
+  tinyobj::attrib_t attrib;
+  std::vector<tinyobj::shape_t> shapes;
+  std::vector<tinyobj::material_t> materials;
+
+  std::string err;
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, "../models/usemtl-issue-104.obj", gMtlBasePath);
+
+  if (!err.empty()) {
+    std::cerr << err << std::endl;
+  }
+  REQUIRE(true == ret);
+  REQUIRE(1 == shapes.size());
+}
+
 #if 0
 int
 main(
diff --git a/tiny_obj_loader.h b/tiny_obj_loader.h
index 0200ff5..6ee59c1 100644
--- a/tiny_obj_loader.h
+++ b/tiny_obj_loader.h
@@ -23,6 +23,7 @@ THE SOFTWARE.
 */
 
 //
+// version 1.0.1 : Fixes a shape is lost if obj ends with a 'usemtl'(#104)
 // version 1.0.0 : Change data structure. Change license from BSD to MIT.
 //
 
@@ -1161,7 +1162,9 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
       }
 
       if (newMaterialId != material) {
-        // Create per-face material
+        // Create per-face material. Thus we don't add `shape` to `shapes` at
+        // this time.
+        // just clear `faceGroup` after `exportFaceGroupToShape()` call.
         exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                triangulate);
         faceGroup.clear();
@@ -1307,7 +1310,11 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
 
   bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
                                     triangulate);
-  if (ret) {
+  // exportFaceGroupToShape return false when `usemtl` is called in the last
+  // line.
+  // we also add `shape` to `shapes` when `shape.mesh` has already some
+  // faces(indices)
+  if (ret || shape.mesh.indices.size()) {
     shapes->push_back(shape);
   }
   faceGroup.clear();  // for safety