DrawPolygon class with Unit Tests

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"
+#include "cc/output/bsp_compare_result.h"
+#include "cc/quads/draw_quad.h"
+#include "ui/gfx/point3_f.h"
+#include "ui/gfx/quad_f.h"
+#include "ui/gfx/vector3d_f.h"
+
+namespace cc {
+
+class DrawPolygon {
+ public:
+  DrawPolygon();
+  ~DrawPolygon();
+
+  DrawPolygon(DrawQuad* original_ref,
+              const std::vector<gfx::Point3F>& in_points,
+              int draw_order_index = 0);
+
+  bool Split(const DrawPolygon& splitter,
+             scoped_ptr<DrawPolygon>* front,
+             scoped_ptr<DrawPolygon>* back);
+  float SignedPointDistance(const gfx::Point3F& point) const;
+  void ApplyTransform(const gfx::Transform& transform);
+
+  // Normalized, necessitated by distance calculations and tests of coplanarity.
+  gfx::Vector3dF normal;
+  float area;
+  // This is an index that can be used to test whether a quad comes before or
+  // after another in document order, useful for tie-breaking when it comes
+  // to coplanar surfaces.
+  int order_index;
+
+  std::vector<gfx::Point3F> points;
+
+  // 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;
+  int NumPoints() { return points.size(); }
+  bool GetInverseTransform(gfx::Transform* transform) const;
+  unsigned int NumberOfPoints() { return points.size(); }
+  const gfx::Point3F& point(unsigned int index) { return points[index]; }
+
+  scoped_ptr<DrawPolygon> CreateCopy();
+
+  // The pointer to the original quad, which gives us all the drawing info
+  // we need.
+  // This DrawQuad is owned by the caller and its lifetime must be preserved
+  // as long as this DrawPolygon is alive.
+  DrawQuad* original_ref;
+
+  // This threshold controls how "thick" a plane is. If a point's distance is
+  // <= compare_threshold, then it is considered on the plane. Only when this
+  // boundary is crossed do we consider doing splitting.
+  static float compare_threshold;
+  static float split_threshold;
+};
+
+}  // namespace cc
+
+#endif  // CC_QUADS_DRAW_POLYGON_H_