Identify files as .obj instead of OBJ.

geometry/proximity_engine.cc

@@ -717,7 +717,7 @@ class ProximityEngine<T>::Impl : public ShapeReifier {
  }
 
  void ImplementGeometry(const Convex& convex, void* user_data) override {
- // We use tiny_obj_loader to read Obj file of the convex shape.
+ // We use tiny_obj_loader to read the .obj file of the convex shape.
  tinyobj::attrib_t attrib;
  std::vector<tinyobj::shape_t> shapes;
  std::vector<tinyobj::material_t> materials;
@@ -745,8 +745,8 @@ class ProximityEngine<T>::Impl : public ShapeReifier {
  //
 
  if (shapes.size() != 1) {
- throw std::runtime_error("For Convex geometry, the OBJ file must have one"
- " and only one object defined in it");
+ throw std::runtime_error("For Convex geometry, the .obj file must have "
+ "one and only one object defined in it.");
  }
 
  std::vector<Vector3d> vertices =

geometry/shape_specification.h

@@ -201,14 +201,14 @@ class Convex final : public Shape {
  given _absolute_ file path. Optionally uniformly scaled by the given scale
  factor.
  @param absolute_filename The file name with absolute path. We only
- support an OBJ file with only one polyhedron.
+ support an .obj file with only one polyhedron.
  We assume that the polyhedron is convex.
  @param scale An optional scale to coordinates.
 
- @throws std::runtime_error if the OBJ file doesn't define a single object.
+ @throws std::runtime_error if the .obj file doesn't define a single object.
  This can happen if it is empty, if there are
- multiple object-name statements (e.g., o
- object name), or if there are faces defined
+ multiple object-name statements (e.g.,
+ "o object_name"), or if there are faces defined
  outside a single object-name statement.
  */
  explicit Convex(const std::string& absolute_filename, double scale = 1.0);

geometry/test/proximity_engine_test.cc

@@ -91,9 +91,9 @@ GTEST_TEST(ProximityEngineTests, AddMixedGeometry) {
  EXPECT_EQ(engine.num_dynamic(), 1);
 }
 
-// Tests for reading OBJ files. ------------------------------------------------
+// Tests for reading .obj files.------------------------------------------------
 
-// Tests exception when we read an OBJ file with two objects into Convex
+// Tests exception when we read an .obj file with two objects into Convex
 GTEST_TEST(ProximityEngineTests, ExceptionTwoObjectsInObjFileForConvex) {
  ProximityEngine<double> engine;
  Convex convex{drake::FindResourceOrThrow(