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