Correct normal computation for inverted polygons.

ui/gfx/transform.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/gfx/transform.h"
 
 #include <cmath>
@@ skipping 389 matching lines @@
 void Transform::TransformPoint(Point* point) const {
   DCHECK(point);
   TransformPointInternal(matrix_, point);
 }
 
 void Transform::TransformPoint(Point3F* point) const {
   DCHECK(point);
   TransformPointInternal(matrix_, point);
 }
 
+void Transform::TransformVector(Vector3dF* vector) const {
+  DCHECK(vector);
+  TransformVectorInternal(matrix_, vector);
+}
+
 bool Transform::TransformPointReverse(Point* point) const {
   DCHECK(point);
 
   // TODO(sad): Try to avoid trying to invert the matrix.
   SkMatrix44 inverse(SkMatrix44::kUninitialized_Constructor);
   if (!matrix_.invert(&inverse))
     return false;
 
   TransformPointInternal(inverse, point);
   return true;
@@ skipping 93 matching lines @@
   xform.mapMScalars(p);
 
   if (p[3] != SK_MScalar1 && p[3] != 0.f) {
     float w_inverse = SK_MScalar1 / p[3];
     point->SetPoint(p[0] * w_inverse, p[1] * w_inverse, p[2] * w_inverse);
   } else {
     point->SetPoint(p[0], p[1], p[2]);
   }
 }
 
+void Transform::TransformVectorInternal(const SkMatrix44& xform,
+                                        Vector3dF* vector) const {
+  if (xform.isIdentity())
+    return;
+
+  SkMScalar p[4] = {SkFloatToMScalar(vector->x()),
+                    SkFloatToMScalar(vector->y()),
+                    SkFloatToMScalar(vector->z()), 0};
+
+  xform.mapMScalars(p);
+
+  vector->set_x(p[0]);
+  vector->set_y(p[1]);
+  vector->set_z(p[2]);
+}
+
 void Transform::TransformPointInternal(const SkMatrix44& xform,
                                        Point* point) const {
   if (xform.isIdentity())
     return;
 
   SkMScalar p[4] = {SkIntToMScalar(point->x()), SkIntToMScalar(point->y()),
                     0, 1};
 
   xform.mapMScalars(p);
 
@@ skipping 39 matching lines @@
       matrix_.get(2, 1),
       matrix_.get(2, 2),
       matrix_.get(2, 3),
       matrix_.get(3, 0),
       matrix_.get(3, 1),
       matrix_.get(3, 2),
       matrix_.get(3, 3));
 }
 
 }  // namespace gfx