cc/output/bsp_tree.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_OUTPUT_BSP_TREE_H_
   6 #define CC_OUTPUT_BSP_TREE_H_
   7
   8 #include <vector>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "cc/base/scoped_ptr_deque.h"
  12 #include "cc/base/scoped_ptr_vector.h"
  13 #include "cc/output/bsp_compare_result.h"
  14 #include "cc/quads/draw_polygon.h"
  15
  16 namespace cc {
  17
  18 struct BspNode {
  19   // This represents the splitting plane.
  20   scoped_ptr<DrawPolygon> node_data;
  21   // This represents any coplanar geometry we found while building the BSP.
  22   ScopedPtrVector<DrawPolygon> coplanars_front;
  23   ScopedPtrVector<DrawPolygon> coplanars_back;
  24
  25   scoped_ptr<BspNode> back_child;
  26   scoped_ptr<BspNode> front_child;
  27
  28   explicit BspNode(scoped_ptr<DrawPolygon> data);
  29   ~BspNode();
  30 };
  31
  32 class CC_EXPORT BspTree {
  33  public:
  34   explicit BspTree(ScopedPtrDeque<DrawPolygon>* list);
  35   scoped_ptr<BspNode>& root() { return root_; }
  36
  37   template <typename ActionHandlerType>
  38   void TraverseWithActionHandler(ActionHandlerType* action_handler) const {
  39     if (root_) {
  40       WalkInOrderRecursion<ActionHandlerType>(action_handler, root_.get());
  41     }
  42   }
  43
  44   ~BspTree();
  45
  46  private:
  47   scoped_ptr<BspNode> root_;
  48
  49   void FromList(ScopedPtrVector<DrawPolygon>* list);
  50   void BuildTree(BspNode* node, ScopedPtrDeque<DrawPolygon>* data);
  51
  52   template <typename ActionHandlerType>
  53   void WalkInOrderAction(ActionHandlerType* action_handler,
  54                          DrawPolygon* item) const {
  55     (*action_handler)(item);
  56   }
  57
  58   template <typename ActionHandlerType>
  59   void WalkInOrderVisitNodes(
  60       ActionHandlerType* action_handler,
  61       const BspNode* node,
  62       const BspNode* first_child,
  63       const BspNode* second_child,
  64       const ScopedPtrVector<DrawPolygon>& first_coplanars,
  65       const ScopedPtrVector<DrawPolygon>& second_coplanars) const {
  66     if (first_child) {
  67       WalkInOrderRecursion(action_handler, first_child);
  68     }
  69     for (size_t i = 0; i < first_coplanars.size(); i++) {
  70       WalkInOrderAction(action_handler, first_coplanars[i]);
  71     }
  72     WalkInOrderAction(action_handler, node->node_data.get());
  73     for (size_t i = 0; i < second_coplanars.size(); i++) {
  74       WalkInOrderAction(action_handler, second_coplanars[i]);
  75     }
  76     if (second_child) {
  77       WalkInOrderRecursion(action_handler, second_child);
  78     }
  79   }
  80
  81   template <typename ActionHandlerType>
  82   void WalkInOrderRecursion(ActionHandlerType* action_handler,
  83                             const BspNode* node) const {
  84     // If our view is in front of the the polygon
  85     // in this node then walk back then front.
  86     if (GetCameraPositionRelative(*(node->node_data)) == BSP_FRONT) {
  87       WalkInOrderVisitNodes<ActionHandlerType>(action_handler,
  88                                                node,
  89                                                node->back_child.get(),
  90                                                node->front_child.get(),
  91                                                node->coplanars_front,
  92                                                node->coplanars_back);
  93     } else {
  94       WalkInOrderVisitNodes<ActionHandlerType>(action_handler,
  95                                                node,
  96                                                node->front_child.get(),
  97                                                node->back_child.get(),
  98                                                node->coplanars_back,
  99                                                node->coplanars_front);
 100     }
 101   }
 102
 103   // Returns whether or not nodeA is on one or the other side of nodeB,
 104   // coplanar, or whether it crosses nodeB's plane and needs to be split
 105   static BspCompareResult GetNodePositionRelative(const DrawPolygon& node_a,
 106                                                   const DrawPolygon& node_b);
 107   // Returns whether or not our viewer is in front of or behind the plane
 108   // defined by this polygon/node
 109   static BspCompareResult GetCameraPositionRelative(const DrawPolygon& node);
 110 };
 111
 112 }  // namespace cc
 113
 114 #endif  // CC_OUTPUT_BSP_TREE_H_