Revert of Perform BSP polygon splitting and orientation selection in a single step.

cc/quads/draw_polygon.h

 // Copyright 2014 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.
 
 #ifndef CC_QUADS_DRAW_POLYGON_H_
 #define CC_QUADS_DRAW_POLYGON_H_
 
 #include <vector>
 
 #include "cc/base/math_util.h"
@@ skipping 22 matching lines @@
               const gfx::Transform& transform,
               int draw_order_index = 0);
 
   // Split takes this DrawPolygon and splits it into two pieces that are on
   // either side of |splitter|. Any edges of this polygon that cross the plane
   // of |splitter| will have an intersection point that is shared by both
   // polygons on either side.
   // Split will only return true if it determines that we got back 2
   // intersection points. Only when it returns true will front and back both be
   // valid new polygons that are on opposite sides of the splitting plane.
-  void SplitPolygon(std::unique_ptr<DrawPolygon> polygon,
-                    std::unique_ptr<DrawPolygon>* front,
-                    std::unique_ptr<DrawPolygon>* back,
-                    bool* is_coplanar) const;
+  bool Split(const DrawPolygon& splitter,
+             std::unique_ptr<DrawPolygon>* front,
+             std::unique_ptr<DrawPolygon>* back);
   float SignedPointDistance(const gfx::Point3F& point) const;
+  // Checks polygon a against polygon b and returns which side it lies on, or
+  // whether it crosses (necessitating a split in the BSP tree).
+  static BspCompareResult SideCompare(const DrawPolygon& a,
+                                      const DrawPolygon& b);
   void ToQuads2D(std::vector<gfx::QuadF>* quads) const;
   void TransformToScreenSpace(const gfx::Transform& transform);
   void TransformToLayerSpace(const gfx::Transform& inverse_transform);
 
   const std::vector<gfx::Point3F>& points() const { return points_; }
   const gfx::Vector3dF& normal() const { return normal_; }
   const DrawQuad* original_ref() const { return original_ref_; }
   int order_index() const { return order_index_; }
   bool is_split() const { return is_split_; }
   std::unique_ptr<DrawPolygon> CreateCopy();
@@ skipping 17 matching lines @@
   // we need.
   // This DrawQuad is owned by the caller and its lifetime must be preserved
   // as long as this DrawPolygon is alive.
   const DrawQuad* original_ref_;
   bool is_split_;
 };
 
 }  // namespace cc
 
 #endif  // CC_QUADS_DRAW_POLYGON_H_