зеркало из https://github.com/mozilla/gecko-dev.git
93 строки
2.8 KiB
C++
93 строки
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_LAYERS_BSPTREE_H
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#define MOZILLA_LAYERS_BSPTREE_H
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#include "mozilla/gfx/Polygon.h"
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#include "mozilla/UniquePtr.h"
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#include "nsTArray.h"
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#include <deque>
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namespace mozilla {
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namespace layers {
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gfx::Polygon3D PopFront(std::deque<gfx::Polygon3D>& aPolygons);
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// Represents a node in a BSP tree. The node contains at least one polygon that
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// is used as a splitting plane, and at most two child nodes that represent the
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// splitting planes that further subdivide the space.
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struct BSPTreeNode {
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explicit BSPTreeNode(gfx::Polygon3D && aPolygon)
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{
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polygons.push_back(std::move(aPolygon));
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}
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const gfx::Polygon3D& First() const
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{
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return polygons[0];
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}
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UniquePtr<BSPTreeNode> front;
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UniquePtr<BSPTreeNode> back;
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std::deque<gfx::Polygon3D> polygons;
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};
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// BSPTree class takes a list of polygons as an input and uses binary space
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// partitioning algorithm to create a tree structure that can be used for
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// depth sorting.
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//
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// Sources for more information:
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// https://en.wikipedia.org/wiki/Binary_space_partitioning
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// ftp://ftp.sgi.com/other/bspfaq/faq/bspfaq.html
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class BSPTree {
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public:
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// This constructor takes the ownership of polygons in the given list.
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explicit BSPTree(std::deque<gfx::Polygon3D>& aPolygons)
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: mRoot(new BSPTreeNode(PopFront(aPolygons)))
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{
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BuildTree(mRoot, aPolygons);
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}
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// Returns the root node of the BSP tree.
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const UniquePtr<BSPTreeNode>& GetRoot() const
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{
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return mRoot;
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}
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// Builds and returns the back-to-front draw order for the created BSP tree.
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nsTArray<gfx::Polygon3D> GetDrawOrder() const
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{
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nsTArray<gfx::Polygon3D> polygons;
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BuildDrawOrder(mRoot, polygons);
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return polygons;
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}
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private:
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UniquePtr<BSPTreeNode> mRoot;
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void BuildDrawOrder(const UniquePtr<BSPTreeNode>& aNode,
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nsTArray<gfx::Polygon3D>& aPolygons) const;
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void BuildTree(UniquePtr<BSPTreeNode>& aRoot,
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std::deque<gfx::Polygon3D>& aPolygons);
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nsTArray<float> CalculateDotProduct(const gfx::Polygon3D& aFirst,
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const gfx::Polygon3D& aSecond,
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size_t& aPos, size_t& aNeg) const;
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void SplitPolygon(const gfx::Polygon3D& aSplittingPlane,
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const gfx::Polygon3D& aPolygon,
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const nsTArray<float>& dots,
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nsTArray<gfx::Point3D>& backPoints,
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nsTArray<gfx::Point3D>& frontPoints);
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};
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} // namespace layers
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} // namespace mozilla
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#endif /* MOZILLA_LAYERS_BSPTREE_H */
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