e89a55d154
I didn't apply the changes to a few macro-heavy files as Visual Studio removes all indentation from macros, whereas the indentation can be handy to see nesting.
353 lines
14 KiB
C++
353 lines
14 KiB
C++
/*******************************************************************************
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 David Williams and Matthew Williams
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*******************************************************************************/
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#include "Impl/ErrorHandling.h"
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namespace PolyVox
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{
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////////////////////////////////////////////////////////////////////////////////
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/// Using this function, a voxel is considered valid for the path if it is inside the
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/// volume and if its density is below that returned by the voxel's getDensity() function.
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/// \return true is the voxel is valid for the path
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////////////////////////////////////////////////////////////////////////////////
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template<typename VolumeType>
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bool aStarDefaultVoxelValidator(const VolumeType* volData, const Vector3DInt32& v3dPos)
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{
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//Voxels are considered valid candidates for the path if they are inside the volume...
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if (volData->getEnclosingRegion().containsPoint(v3dPos) == false)
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{
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return false;
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}
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return true;
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}
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////////////////////////////////////////////////////////////////////////////////
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// AStarPathfinder Class
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////////////////////////////////////////////////////////////////////////////////
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template<typename VolumeType>
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AStarPathfinder<VolumeType>::AStarPathfinder(const AStarPathfinderParams<VolumeType>& params)
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:m_params(params)
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{
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}
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template<typename VolumeType>
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void AStarPathfinder<VolumeType>::execute()
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{
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//Clear any existing nodes
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allNodes.clear();
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openNodes.clear();
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closedNodes.clear();
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//Clear the result
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m_params.result->clear();
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//Iterators to start and end node.
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AllNodesContainer::iterator startNode = allNodes.insert(Node(m_params.start.getX(), m_params.start.getY(), m_params.start.getZ())).first;
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AllNodesContainer::iterator endNode = allNodes.insert(Node(m_params.end.getX(), m_params.end.getY(), m_params.end.getZ())).first;
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//Regarding the const_cast - normally you should not modify an object which is in an sdt::set.
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//The reason is that objects in a set are stored sorted in a tree so they can be accessed quickly,
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//and changing the object directly can break the sorting. However, in our case we have provided a
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//custom sort operator for the set which we know only uses the position to sort. Hence we can safely
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//modify other properties of the object while it is in the set.
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Node* tempStart = const_cast<Node*>(&(*startNode));
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tempStart->gVal = 0;
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tempStart->hVal = computeH(startNode->position, endNode->position);
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Node* tempEnd = const_cast<Node*>(&(*endNode));
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tempEnd->hVal = 0.0f;
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openNodes.insert(startNode);
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float fDistStartToEnd = (endNode->position - startNode->position).length();
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m_fProgress = 0.0f;
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if (m_params.progressCallback)
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{
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m_params.progressCallback(m_fProgress);
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}
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while ((openNodes.empty() == false) && (openNodes.getFirst() != endNode))
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{
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//Move the first node from open to closed.
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current = openNodes.getFirst();
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openNodes.removeFirst();
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closedNodes.insert(current);
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//Update the user on our progress
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if (m_params.progressCallback)
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{
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const float fMinProgresIncreament = 0.001f;
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float fDistCurrentToEnd = (endNode->position - current->position).length();
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float fDistNormalised = fDistCurrentToEnd / fDistStartToEnd;
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float fProgress = 1.0f - fDistNormalised;
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if (fProgress >= m_fProgress + fMinProgresIncreament)
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{
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m_fProgress = fProgress;
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m_params.progressCallback(m_fProgress);
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}
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}
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//The distance from one cell to another connected by face, edge, or corner.
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const float fFaceCost = sqrt_1;
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const float fEdgeCost = sqrt_2;
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const float fCornerCost = sqrt_3;
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//Process the neighbours. Note the deliberate lack of 'break'
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//statements, larger connectivities include smaller ones.
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switch (m_params.connectivity)
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{
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case TwentySixConnected:
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processNeighbour(current->position + arrayPathfinderCorners[0], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[1], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[2], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[3], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[4], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[5], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[6], current->gVal + fCornerCost);
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processNeighbour(current->position + arrayPathfinderCorners[7], current->gVal + fCornerCost);
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case EighteenConnected:
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processNeighbour(current->position + arrayPathfinderEdges[0], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[1], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[2], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[3], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[4], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[5], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[6], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[7], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[8], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[9], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[10], current->gVal + fEdgeCost);
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processNeighbour(current->position + arrayPathfinderEdges[11], current->gVal + fEdgeCost);
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case SixConnected:
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processNeighbour(current->position + arrayPathfinderFaces[0], current->gVal + fFaceCost);
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processNeighbour(current->position + arrayPathfinderFaces[1], current->gVal + fFaceCost);
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processNeighbour(current->position + arrayPathfinderFaces[2], current->gVal + fFaceCost);
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processNeighbour(current->position + arrayPathfinderFaces[3], current->gVal + fFaceCost);
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processNeighbour(current->position + arrayPathfinderFaces[4], current->gVal + fFaceCost);
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processNeighbour(current->position + arrayPathfinderFaces[5], current->gVal + fFaceCost);
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}
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if (allNodes.size() > m_params.maxNumberOfNodes)
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{
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//We've reached the specified maximum number
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//of nodes. Just give up on the search.
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break;
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}
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}
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if ((openNodes.empty()) || (openNodes.getFirst() != endNode))
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{
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//In this case we failed to find a valid path.
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POLYVOX_THROW(std::runtime_error, "No path found");
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}
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else
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{
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//Regarding the const_cast - normally you should not modify an object which is in an sdt::set.
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//The reason is that objects in a set are stored sorted in a tree so they can be accessed quickly,
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//and changing the object directly can break the sorting. However, in our case we have provided a
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//custom sort operator for the set which we know only uses the position to sort. Hence we can safely
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//modify other properties of the object while it is in the set.
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Node* n = const_cast<Node*>(&(*endNode));
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while (n != 0)
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{
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m_params.result->push_front(n->position);
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n = n->parent;
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}
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}
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if (m_params.progressCallback)
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{
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m_params.progressCallback(1.0f);
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}
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}
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template<typename VolumeType>
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void AStarPathfinder<VolumeType>::processNeighbour(const Vector3DInt32& neighbourPos, float neighbourGVal)
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{
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bool bIsVoxelValidForPath = m_params.isVoxelValidForPath(m_params.volume, neighbourPos);
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if (!bIsVoxelValidForPath)
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{
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return;
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}
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float cost = neighbourGVal;
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std::pair<AllNodesContainer::iterator, bool> insertResult = allNodes.insert(Node(neighbourPos.getX(), neighbourPos.getY(), neighbourPos.getZ()));
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AllNodesContainer::iterator neighbour = insertResult.first;
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if (insertResult.second == true) //New node, compute h.
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{
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Node* tempNeighbour = const_cast<Node*>(&(*neighbour));
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tempNeighbour->hVal = computeH(neighbour->position, m_params.end);
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}
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OpenNodesContainer::iterator openIter = openNodes.find(neighbour);
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if (openIter != openNodes.end())
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{
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if (cost < neighbour->gVal)
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{
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openNodes.remove(openIter);
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openIter = openNodes.end();
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}
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}
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//TODO - Nodes could keep track of if they are in open or closed? And a pointer to where they are?
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ClosedNodesContainer::iterator closedIter = closedNodes.find(neighbour);
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if (closedIter != closedNodes.end())
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{
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if (cost < neighbour->gVal)
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{
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//Probably shouldn't happen?
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closedNodes.remove(closedIter);
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closedIter = closedNodes.end();
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}
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}
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if ((openIter == openNodes.end()) && (closedIter == closedNodes.end()))
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{
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//Regarding the const_cast - normally you should not modify an object which is in an sdt::set.
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//The reason is that objects in a set are stored sorted in a tree so they can be accessed quickly,
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//and changing the object directly can break the sorting. However, in our case we have provided a
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//custom sort operator for the set which we know only uses the position to sort. Hence we can safely
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//modify other properties of the object while it is in the set.
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Node* temp = const_cast<Node*>(&(*neighbour));
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temp->gVal = cost;
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openNodes.insert(neighbour);
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temp->parent = const_cast<Node*>(&(*current));
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}
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}
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template<typename VolumeType>
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float AStarPathfinder<VolumeType>::SixConnectedCost(const Vector3DInt32& a, const Vector3DInt32& b)
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{
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//This is the only heuristic I'm sure of - just use the manhatten distance for the 6-connected case.
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uint32_t faceSteps = std::abs(a.getX() - b.getX()) + std::abs(a.getY() - b.getY()) + std::abs(a.getZ() - b.getZ());
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return faceSteps * 1.0f;
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}
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template<typename VolumeType>
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float AStarPathfinder<VolumeType>::EighteenConnectedCost(const Vector3DInt32& a, const Vector3DInt32& b)
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{
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//I'm not sure of the correct heuristic for the 18-connected case, so I'm just letting it fall through to the
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//6-connected case. This means 'h' will be bigger than it should be, resulting in a faster path which may not
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//actually be the shortest one. If you have a correct heuristic for the 18-connected case then please let me know.
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return SixConnectedCost(a, b);
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}
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template<typename VolumeType>
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float AStarPathfinder<VolumeType>::TwentySixConnectedCost(const Vector3DInt32& a, const Vector3DInt32& b)
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{
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//Can't say I'm certain about this heuristic - if anyone has
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//a better idea of what it should be then please let me know.
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uint32_t array[3];
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array[0] = std::abs(a.getX() - b.getX());
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array[1] = std::abs(a.getY() - b.getY());
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array[2] = std::abs(a.getZ() - b.getZ());
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//Maybe this is better implemented directly
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//using three compares and two swaps... but not
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//until the profiler says so.
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std::sort(&array[0], &array[3]);
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uint32_t cornerSteps = array[0];
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uint32_t edgeSteps = array[1] - array[0];
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uint32_t faceSteps = array[2] - array[1];
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return cornerSteps * sqrt_3 + edgeSteps * sqrt_2 + faceSteps * sqrt_1;
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}
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template<typename VolumeType>
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float AStarPathfinder<VolumeType>::computeH(const Vector3DInt32& a, const Vector3DInt32& b)
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{
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float hVal;
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switch (m_params.connectivity)
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{
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case TwentySixConnected:
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hVal = TwentySixConnectedCost(a, b);
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break;
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case EighteenConnected:
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hVal = EighteenConnectedCost(a, b);
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break;
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case SixConnected:
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hVal = SixConnectedCost(a, b);
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break;
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default:
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POLYVOX_THROW(std::invalid_argument, "Connectivity parameter has an unrecognised value.");
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}
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//Sanity checks in debug mode. These can come out eventually, but I
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//want to make sure that the heuristics I've come up with make sense.
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POLYVOX_ASSERT((a - b).length() <= TwentySixConnectedCost(a, b), "A* heuristic error.");
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POLYVOX_ASSERT(TwentySixConnectedCost(a, b) <= EighteenConnectedCost(a, b), "A* heuristic error.");
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POLYVOX_ASSERT(EighteenConnectedCost(a, b) <= SixConnectedCost(a, b), "A* heuristic error.");
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//Apply the bias to the computed h value;
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hVal *= m_params.hBias;
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//Having computed hVal, we now apply some random bias to break ties.
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//This needs to be deterministic on the input position. This random
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//bias means it is much les likely that two paths are exactly the same
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//length, and so far fewer nodes must be expanded to find the shortest path.
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//See http://theory.stanford.edu/~amitp/GameProgramming/Heuristics.html#S12
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//Note that if the hash is zero we can have differences between the Linux vs. Windows
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//(or perhaps GCC vs. VS) versions of the code. This is probably because of the way
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//sorting inside the std::set works (i.e. one system swaps values which are identical
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//while the other one doesn't - both approaches are valid). For the same reason we want
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//to make sure that position (x,y,z) has a differnt hash from e.g. position (x,z,y).
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uint32_t aX = (a.getX() << 16) & 0x00FF0000;
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uint32_t aY = (a.getY() << 8) & 0x0000FF00;
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uint32_t aZ = (a.getZ()) & 0x000000FF;
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uint32_t hashVal = hash(aX | aY | aZ);
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//Stop hashVal going over 65535, and divide by 1000000 to make sure it is small.
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hashVal &= 0x0000FFFF;
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float fHash = hashVal / 1000000.0f;
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//Apply the hash and return
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hVal += fHash;
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return hVal;
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}
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// Robert Jenkins' 32 bit integer hash function
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// http://www.burtleburtle.net/bob/hash/integer.html
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template<typename VolumeType>
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uint32_t AStarPathfinder<VolumeType>::hash(uint32_t a)
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{
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a = (a + 0x7ed55d16) + (a << 12);
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a = (a ^ 0xc761c23c) ^ (a >> 19);
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a = (a + 0x165667b1) + (a << 5);
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a = (a + 0xd3a2646c) ^ (a << 9);
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a = (a + 0xfd7046c5) + (a << 3);
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a = (a ^ 0xb55a4f09) ^ (a >> 16);
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return a;
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}
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}
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