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Diffstat (limited to 'Client/ThirdParty/Box2D/src/collision/b2_dynamic_tree.cpp')
| -rw-r--r-- | Client/ThirdParty/Box2D/src/collision/b2_dynamic_tree.cpp | 801 |
1 files changed, 801 insertions, 0 deletions
diff --git a/Client/ThirdParty/Box2D/src/collision/b2_dynamic_tree.cpp b/Client/ThirdParty/Box2D/src/collision/b2_dynamic_tree.cpp new file mode 100644 index 0000000..55a9d32 --- /dev/null +++ b/Client/ThirdParty/Box2D/src/collision/b2_dynamic_tree.cpp @@ -0,0 +1,801 @@ +// MIT License + +// Copyright (c) 2019 Erin Catto + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. +#include "box2d/b2_dynamic_tree.h" +#include <string.h> + +b2DynamicTree::b2DynamicTree() +{ + m_root = b2_nullNode; + + m_nodeCapacity = 16; + m_nodeCount = 0; + m_nodes = (b2TreeNode*)b2Alloc(m_nodeCapacity * sizeof(b2TreeNode)); + memset(m_nodes, 0, m_nodeCapacity * sizeof(b2TreeNode)); + + // Build a linked list for the free list. + for (int32 i = 0; i < m_nodeCapacity - 1; ++i) + { + m_nodes[i].next = i + 1; + m_nodes[i].height = -1; + } + m_nodes[m_nodeCapacity-1].next = b2_nullNode; + m_nodes[m_nodeCapacity-1].height = -1; + m_freeList = 0; + + m_insertionCount = 0; +} + +b2DynamicTree::~b2DynamicTree() +{ + // This frees the entire tree in one shot. + b2Free(m_nodes); +} + +// Allocate a node from the pool. Grow the pool if necessary. +int32 b2DynamicTree::AllocateNode() +{ + // Expand the node pool as needed. + if (m_freeList == b2_nullNode) + { + b2Assert(m_nodeCount == m_nodeCapacity); + + // The free list is empty. Rebuild a bigger pool. + b2TreeNode* oldNodes = m_nodes; + m_nodeCapacity *= 2; + m_nodes = (b2TreeNode*)b2Alloc(m_nodeCapacity * sizeof(b2TreeNode)); + memcpy(m_nodes, oldNodes, m_nodeCount * sizeof(b2TreeNode)); + b2Free(oldNodes); + + // Build a linked list for the free list. The parent + // pointer becomes the "next" pointer. + for (int32 i = m_nodeCount; i < m_nodeCapacity - 1; ++i) + { + m_nodes[i].next = i + 1; + m_nodes[i].height = -1; + } + m_nodes[m_nodeCapacity-1].next = b2_nullNode; + m_nodes[m_nodeCapacity-1].height = -1; + m_freeList = m_nodeCount; + } + + // Peel a node off the free list. + int32 nodeId = m_freeList; + m_freeList = m_nodes[nodeId].next; + m_nodes[nodeId].parent = b2_nullNode; + m_nodes[nodeId].child1 = b2_nullNode; + m_nodes[nodeId].child2 = b2_nullNode; + m_nodes[nodeId].height = 0; + m_nodes[nodeId].userData = nullptr; + m_nodes[nodeId].moved = false; + ++m_nodeCount; + return nodeId; +} + +// Return a node to the pool. +void b2DynamicTree::FreeNode(int32 nodeId) +{ + b2Assert(0 <= nodeId && nodeId < m_nodeCapacity); + b2Assert(0 < m_nodeCount); + m_nodes[nodeId].next = m_freeList; + m_nodes[nodeId].height = -1; + m_freeList = nodeId; + --m_nodeCount; +} + +// Create a proxy in the tree as a leaf node. We return the index +// of the node instead of a pointer so that we can grow +// the node pool. +int32 b2DynamicTree::CreateProxy(const b2AABB& aabb, void* userData) +{ + int32 proxyId = AllocateNode(); + + // Fatten the aabb. + b2Vec2 r(b2_aabbExtension, b2_aabbExtension); + m_nodes[proxyId].aabb.lowerBound = aabb.lowerBound - r; + m_nodes[proxyId].aabb.upperBound = aabb.upperBound + r; + m_nodes[proxyId].userData = userData; + m_nodes[proxyId].height = 0; + m_nodes[proxyId].moved = true; + + InsertLeaf(proxyId); + + return proxyId; +} + +void b2DynamicTree::DestroyProxy(int32 proxyId) +{ + b2Assert(0 <= proxyId && proxyId < m_nodeCapacity); + b2Assert(m_nodes[proxyId].IsLeaf()); + + RemoveLeaf(proxyId); + FreeNode(proxyId); +} + +bool b2DynamicTree::MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement) +{ + b2Assert(0 <= proxyId && proxyId < m_nodeCapacity); + + b2Assert(m_nodes[proxyId].IsLeaf()); + + // Extend AABB + b2AABB fatAABB; + b2Vec2 r(b2_aabbExtension, b2_aabbExtension); + fatAABB.lowerBound = aabb.lowerBound - r; + fatAABB.upperBound = aabb.upperBound + r; + + // Predict AABB movement + b2Vec2 d = b2_aabbMultiplier * displacement; + + if (d.x < 0.0f) + { + fatAABB.lowerBound.x += d.x; + } + else + { + fatAABB.upperBound.x += d.x; + } + + if (d.y < 0.0f) + { + fatAABB.lowerBound.y += d.y; + } + else + { + fatAABB.upperBound.y += d.y; + } + + const b2AABB& treeAABB = m_nodes[proxyId].aabb; + if (treeAABB.Contains(aabb)) + { + // The tree AABB still contains the object, but it might be too large. + // Perhaps the object was moving fast but has since gone to sleep. + // The huge AABB is larger than the new fat AABB. + b2AABB hugeAABB; + hugeAABB.lowerBound = fatAABB.lowerBound - 4.0f * r; + hugeAABB.upperBound = fatAABB.upperBound + 4.0f * r; + + if (hugeAABB.Contains(treeAABB)) + { + // The tree AABB contains the object AABB and the tree AABB is + // not too large. No tree update needed. + return false; + } + + // Otherwise the tree AABB is huge and needs to be shrunk + } + + RemoveLeaf(proxyId); + + m_nodes[proxyId].aabb = fatAABB; + + InsertLeaf(proxyId); + + m_nodes[proxyId].moved = true; + + return true; +} + +void b2DynamicTree::InsertLeaf(int32 leaf) +{ + ++m_insertionCount; + + if (m_root == b2_nullNode) + { + m_root = leaf; + m_nodes[m_root].parent = b2_nullNode; + return; + } + + // Find the best sibling for this node + b2AABB leafAABB = m_nodes[leaf].aabb; + int32 index = m_root; + while (m_nodes[index].IsLeaf() == false) + { + int32 child1 = m_nodes[index].child1; + int32 child2 = m_nodes[index].child2; + + float area = m_nodes[index].aabb.GetPerimeter(); + + b2AABB combinedAABB; + combinedAABB.Combine(m_nodes[index].aabb, leafAABB); + float combinedArea = combinedAABB.GetPerimeter(); + + // Cost of creating a new parent for this node and the new leaf + float cost = 2.0f * combinedArea; + + // Minimum cost of pushing the leaf further down the tree + float inheritanceCost = 2.0f * (combinedArea - area); + + // Cost of descending into child1 + float cost1; + if (m_nodes[child1].IsLeaf()) + { + b2AABB aabb; + aabb.Combine(leafAABB, m_nodes[child1].aabb); + cost1 = aabb.GetPerimeter() + inheritanceCost; + } + else + { + b2AABB aabb; + aabb.Combine(leafAABB, m_nodes[child1].aabb); + float oldArea = m_nodes[child1].aabb.GetPerimeter(); + float newArea = aabb.GetPerimeter(); + cost1 = (newArea - oldArea) + inheritanceCost; + } + + // Cost of descending into child2 + float cost2; + if (m_nodes[child2].IsLeaf()) + { + b2AABB aabb; + aabb.Combine(leafAABB, m_nodes[child2].aabb); + cost2 = aabb.GetPerimeter() + inheritanceCost; + } + else + { + b2AABB aabb; + aabb.Combine(leafAABB, m_nodes[child2].aabb); + float oldArea = m_nodes[child2].aabb.GetPerimeter(); + float newArea = aabb.GetPerimeter(); + cost2 = newArea - oldArea + inheritanceCost; + } + + // Descend according to the minimum cost. + if (cost < cost1 && cost < cost2) + { + break; + } + + // Descend + if (cost1 < cost2) + { + index = child1; + } + else + { + index = child2; + } + } + + int32 sibling = index; + + // Create a new parent. + int32 oldParent = m_nodes[sibling].parent; + int32 newParent = AllocateNode(); + m_nodes[newParent].parent = oldParent; + m_nodes[newParent].userData = nullptr; + m_nodes[newParent].aabb.Combine(leafAABB, m_nodes[sibling].aabb); + m_nodes[newParent].height = m_nodes[sibling].height + 1; + + if (oldParent != b2_nullNode) + { + // The sibling was not the root. + if (m_nodes[oldParent].child1 == sibling) + { + m_nodes[oldParent].child1 = newParent; + } + else + { + m_nodes[oldParent].child2 = newParent; + } + + m_nodes[newParent].child1 = sibling; + m_nodes[newParent].child2 = leaf; + m_nodes[sibling].parent = newParent; + m_nodes[leaf].parent = newParent; + } + else + { + // The sibling was the root. + m_nodes[newParent].child1 = sibling; + m_nodes[newParent].child2 = leaf; + m_nodes[sibling].parent = newParent; + m_nodes[leaf].parent = newParent; + m_root = newParent; + } + + // Walk back up the tree fixing heights and AABBs + index = m_nodes[leaf].parent; + while (index != b2_nullNode) + { + index = Balance(index); + + int32 child1 = m_nodes[index].child1; + int32 child2 = m_nodes[index].child2; + + b2Assert(child1 != b2_nullNode); + b2Assert(child2 != b2_nullNode); + + m_nodes[index].height = 1 + b2Max(m_nodes[child1].height, m_nodes[child2].height); + m_nodes[index].aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb); + + index = m_nodes[index].parent; + } + + //Validate(); +} + +void b2DynamicTree::RemoveLeaf(int32 leaf) +{ + if (leaf == m_root) + { + m_root = b2_nullNode; + return; + } + + int32 parent = m_nodes[leaf].parent; + int32 grandParent = m_nodes[parent].parent; + int32 sibling; + if (m_nodes[parent].child1 == leaf) + { + sibling = m_nodes[parent].child2; + } + else + { + sibling = m_nodes[parent].child1; + } + + if (grandParent != b2_nullNode) + { + // Destroy parent and connect sibling to grandParent. + if (m_nodes[grandParent].child1 == parent) + { + m_nodes[grandParent].child1 = sibling; + } + else + { + m_nodes[grandParent].child2 = sibling; + } + m_nodes[sibling].parent = grandParent; + FreeNode(parent); + + // Adjust ancestor bounds. + int32 index = grandParent; + while (index != b2_nullNode) + { + index = Balance(index); + + int32 child1 = m_nodes[index].child1; + int32 child2 = m_nodes[index].child2; + + m_nodes[index].aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb); + m_nodes[index].height = 1 + b2Max(m_nodes[child1].height, m_nodes[child2].height); + + index = m_nodes[index].parent; + } + } + else + { + m_root = sibling; + m_nodes[sibling].parent = b2_nullNode; + FreeNode(parent); + } + + //Validate(); +} + +// Perform a left or right rotation if node A is imbalanced. +// Returns the new root index. +int32 b2DynamicTree::Balance(int32 iA) +{ + b2Assert(iA != b2_nullNode); + + b2TreeNode* A = m_nodes + iA; + if (A->IsLeaf() || A->height < 2) + { + return iA; + } + + int32 iB = A->child1; + int32 iC = A->child2; + b2Assert(0 <= iB && iB < m_nodeCapacity); + b2Assert(0 <= iC && iC < m_nodeCapacity); + + b2TreeNode* B = m_nodes + iB; + b2TreeNode* C = m_nodes + iC; + + int32 balance = C->height - B->height; + + // Rotate C up + if (balance > 1) + { + int32 iF = C->child1; + int32 iG = C->child2; + b2TreeNode* F = m_nodes + iF; + b2TreeNode* G = m_nodes + iG; + b2Assert(0 <= iF && iF < m_nodeCapacity); + b2Assert(0 <= iG && iG < m_nodeCapacity); + + // Swap A and C + C->child1 = iA; + C->parent = A->parent; + A->parent = iC; + + // A's old parent should point to C + if (C->parent != b2_nullNode) + { + if (m_nodes[C->parent].child1 == iA) + { + m_nodes[C->parent].child1 = iC; + } + else + { + b2Assert(m_nodes[C->parent].child2 == iA); + m_nodes[C->parent].child2 = iC; + } + } + else + { + m_root = iC; + } + + // Rotate + if (F->height > G->height) + { + C->child2 = iF; + A->child2 = iG; + G->parent = iA; + A->aabb.Combine(B->aabb, G->aabb); + C->aabb.Combine(A->aabb, F->aabb); + + A->height = 1 + b2Max(B->height, G->height); + C->height = 1 + b2Max(A->height, F->height); + } + else + { + C->child2 = iG; + A->child2 = iF; + F->parent = iA; + A->aabb.Combine(B->aabb, F->aabb); + C->aabb.Combine(A->aabb, G->aabb); + + A->height = 1 + b2Max(B->height, F->height); + C->height = 1 + b2Max(A->height, G->height); + } + + return iC; + } + + // Rotate B up + if (balance < -1) + { + int32 iD = B->child1; + int32 iE = B->child2; + b2TreeNode* D = m_nodes + iD; + b2TreeNode* E = m_nodes + iE; + b2Assert(0 <= iD && iD < m_nodeCapacity); + b2Assert(0 <= iE && iE < m_nodeCapacity); + + // Swap A and B + B->child1 = iA; + B->parent = A->parent; + A->parent = iB; + + // A's old parent should point to B + if (B->parent != b2_nullNode) + { + if (m_nodes[B->parent].child1 == iA) + { + m_nodes[B->parent].child1 = iB; + } + else + { + b2Assert(m_nodes[B->parent].child2 == iA); + m_nodes[B->parent].child2 = iB; + } + } + else + { + m_root = iB; + } + + // Rotate + if (D->height > E->height) + { + B->child2 = iD; + A->child1 = iE; + E->parent = iA; + A->aabb.Combine(C->aabb, E->aabb); + B->aabb.Combine(A->aabb, D->aabb); + + A->height = 1 + b2Max(C->height, E->height); + B->height = 1 + b2Max(A->height, D->height); + } + else + { + B->child2 = iE; + A->child1 = iD; + D->parent = iA; + A->aabb.Combine(C->aabb, D->aabb); + B->aabb.Combine(A->aabb, E->aabb); + + A->height = 1 + b2Max(C->height, D->height); + B->height = 1 + b2Max(A->height, E->height); + } + + return iB; + } + + return iA; +} + +int32 b2DynamicTree::GetHeight() const +{ + if (m_root == b2_nullNode) + { + return 0; + } + + return m_nodes[m_root].height; +} + +// +float b2DynamicTree::GetAreaRatio() const +{ + if (m_root == b2_nullNode) + { + return 0.0f; + } + + const b2TreeNode* root = m_nodes + m_root; + float rootArea = root->aabb.GetPerimeter(); + + float totalArea = 0.0f; + for (int32 i = 0; i < m_nodeCapacity; ++i) + { + const b2TreeNode* node = m_nodes + i; + if (node->height < 0) + { + // Free node in pool + continue; + } + + totalArea += node->aabb.GetPerimeter(); + } + + return totalArea / rootArea; +} + +// Compute the height of a sub-tree. +int32 b2DynamicTree::ComputeHeight(int32 nodeId) const +{ + b2Assert(0 <= nodeId && nodeId < m_nodeCapacity); + b2TreeNode* node = m_nodes + nodeId; + + if (node->IsLeaf()) + { + return 0; + } + + int32 height1 = ComputeHeight(node->child1); + int32 height2 = ComputeHeight(node->child2); + return 1 + b2Max(height1, height2); +} + +int32 b2DynamicTree::ComputeHeight() const +{ + int32 height = ComputeHeight(m_root); + return height; +} + +void b2DynamicTree::ValidateStructure(int32 index) const +{ + if (index == b2_nullNode) + { + return; + } + + if (index == m_root) + { + b2Assert(m_nodes[index].parent == b2_nullNode); + } + + const b2TreeNode* node = m_nodes + index; + + int32 child1 = node->child1; + int32 child2 = node->child2; + + if (node->IsLeaf()) + { + b2Assert(child1 == b2_nullNode); + b2Assert(child2 == b2_nullNode); + b2Assert(node->height == 0); + return; + } + + b2Assert(0 <= child1 && child1 < m_nodeCapacity); + b2Assert(0 <= child2 && child2 < m_nodeCapacity); + + b2Assert(m_nodes[child1].parent == index); + b2Assert(m_nodes[child2].parent == index); + + ValidateStructure(child1); + ValidateStructure(child2); +} + +void b2DynamicTree::ValidateMetrics(int32 index) const +{ + if (index == b2_nullNode) + { + return; + } + + const b2TreeNode* node = m_nodes + index; + + int32 child1 = node->child1; + int32 child2 = node->child2; + + if (node->IsLeaf()) + { + b2Assert(child1 == b2_nullNode); + b2Assert(child2 == b2_nullNode); + b2Assert(node->height == 0); + return; + } + + b2Assert(0 <= child1 && child1 < m_nodeCapacity); + b2Assert(0 <= child2 && child2 < m_nodeCapacity); + + int32 height1 = m_nodes[child1].height; + int32 height2 = m_nodes[child2].height; + int32 height; + height = 1 + b2Max(height1, height2); + b2Assert(node->height == height); + + b2AABB aabb; + aabb.Combine(m_nodes[child1].aabb, m_nodes[child2].aabb); + + b2Assert(aabb.lowerBound == node->aabb.lowerBound); + b2Assert(aabb.upperBound == node->aabb.upperBound); + + ValidateMetrics(child1); + ValidateMetrics(child2); +} + +void b2DynamicTree::Validate() const +{ +#if defined(b2DEBUG) + ValidateStructure(m_root); + ValidateMetrics(m_root); + + int32 freeCount = 0; + int32 freeIndex = m_freeList; + while (freeIndex != b2_nullNode) + { + b2Assert(0 <= freeIndex && freeIndex < m_nodeCapacity); + freeIndex = m_nodes[freeIndex].next; + ++freeCount; + } + + b2Assert(GetHeight() == ComputeHeight()); + + b2Assert(m_nodeCount + freeCount == m_nodeCapacity); +#endif +} + +int32 b2DynamicTree::GetMaxBalance() const +{ + int32 maxBalance = 0; + for (int32 i = 0; i < m_nodeCapacity; ++i) + { + const b2TreeNode* node = m_nodes + i; + if (node->height <= 1) + { + continue; + } + + b2Assert(node->IsLeaf() == false); + + int32 child1 = node->child1; + int32 child2 = node->child2; + int32 balance = b2Abs(m_nodes[child2].height - m_nodes[child1].height); + maxBalance = b2Max(maxBalance, balance); + } + + return maxBalance; +} + +void b2DynamicTree::RebuildBottomUp() +{ + int32* nodes = (int32*)b2Alloc(m_nodeCount * sizeof(int32)); + int32 count = 0; + + // Build array of leaves. Free the rest. + for (int32 i = 0; i < m_nodeCapacity; ++i) + { + if (m_nodes[i].height < 0) + { + // free node in pool + continue; + } + + if (m_nodes[i].IsLeaf()) + { + m_nodes[i].parent = b2_nullNode; + nodes[count] = i; + ++count; + } + else + { + FreeNode(i); + } + } + + while (count > 1) + { + float minCost = b2_maxFloat; + int32 iMin = -1, jMin = -1; + for (int32 i = 0; i < count; ++i) + { + b2AABB aabbi = m_nodes[nodes[i]].aabb; + + for (int32 j = i + 1; j < count; ++j) + { + b2AABB aabbj = m_nodes[nodes[j]].aabb; + b2AABB b; + b.Combine(aabbi, aabbj); + float cost = b.GetPerimeter(); + if (cost < minCost) + { + iMin = i; + jMin = j; + minCost = cost; + } + } + } + + int32 index1 = nodes[iMin]; + int32 index2 = nodes[jMin]; + b2TreeNode* child1 = m_nodes + index1; + b2TreeNode* child2 = m_nodes + index2; + + int32 parentIndex = AllocateNode(); + b2TreeNode* parent = m_nodes + parentIndex; + parent->child1 = index1; + parent->child2 = index2; + parent->height = 1 + b2Max(child1->height, child2->height); + parent->aabb.Combine(child1->aabb, child2->aabb); + parent->parent = b2_nullNode; + + child1->parent = parentIndex; + child2->parent = parentIndex; + + nodes[jMin] = nodes[count-1]; + nodes[iMin] = parentIndex; + --count; + } + + m_root = nodes[0]; + b2Free(nodes); + + Validate(); +} + +void b2DynamicTree::ShiftOrigin(const b2Vec2& newOrigin) +{ + // Build array of leaves. Free the rest. + for (int32 i = 0; i < m_nodeCapacity; ++i) + { + m_nodes[i].aabb.lowerBound -= newOrigin; + m_nodes[i].aabb.upperBound -= newOrigin; + } +} |