pandemonium_engine/core/math/bvh_logic.inc

231 lines
6.4 KiB
C++

// for slow incremental optimization, we will periodically remove each
// item from the tree and reinsert, to give it a chance to find a better position
void _logic_item_remove_and_reinsert(uint32_t p_ref_id) {
// get the reference
ItemRef &ref = _refs[p_ref_id];
// no need to optimize inactive items
if (!ref.is_active()) {
return;
}
// special case of debug draw
if (ref.item_id == BVHCommon::INVALID) {
return;
}
BVH_ASSERT(ref.tnode_id != BVHCommon::INVALID);
// some overlay elaborate way to find out which tree the node is in!
BVHHandle temp_handle;
temp_handle.set_id(p_ref_id);
uint32_t tree_id = _handle_get_tree_id(temp_handle);
// remove and reinsert
BVHABB_CLASS abb;
node_remove_item(p_ref_id, tree_id, &abb);
// we must choose where to add to tree
ref.tnode_id = _logic_choose_item_add_node(_root_node_id[tree_id], abb);
_node_add_item(ref.tnode_id, p_ref_id, abb);
refit_upward_and_balance(ref.tnode_id, tree_id);
}
// from randy gaul balance function
BVHABB_CLASS _logic_abb_merge(const BVHABB_CLASS &a, const BVHABB_CLASS &b) {
BVHABB_CLASS c = a;
c.merge(b);
return c;
}
//--------------------------------------------------------------------------------------------------
/**
* @file q3DynamicAABBTree.h
* @author Randy Gaul
* @date 10/10/2014
* Copyright (c) 2014 Randy Gaul http://www.randygaul.net
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not
* be misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
//--------------------------------------------------------------------------------------------------
// This function is based on the 'Balance' function from Randy Gaul's qu3e
// https://github.com/RandyGaul/qu3e
// It is MODIFIED from qu3e version.
// This is the only function used (and _logic_abb_merge helper function).
int32_t _logic_balance(int32_t iA, uint32_t p_tree_id) {
//return iA; // uncomment this to bypass balance
TNode *A = &_nodes[iA];
if (A->is_leaf() || A->height == 1) {
return iA;
}
/* A
* / \
* B C
* / \ / \
* D E F G
*/
CRASH_COND(A->num_children != 2);
int32_t iB = A->children[0];
int32_t iC = A->children[1];
TNode *B = &_nodes[iB];
TNode *C = &_nodes[iC];
int32_t balance = C->height - B->height;
// C is higher, promote C
if (balance > 1) {
int32_t iF = C->children[0];
int32_t iG = C->children[1];
TNode *F = &_nodes[iF];
TNode *G = &_nodes[iG];
// grandParent point to C
if (A->parent_id != BVHCommon::INVALID) {
if (_nodes[A->parent_id].children[0] == iA) {
_nodes[A->parent_id].children[0] = iC;
} else {
_nodes[A->parent_id].children[1] = iC;
}
} else {
// check this .. seems dodgy
change_root_node(iC, p_tree_id);
}
// Swap A and C
C->children[0] = iA;
C->parent_id = A->parent_id;
A->parent_id = iC;
// Finish rotation
if (F->height > G->height) {
C->children[1] = iF;
A->children[1] = iG;
G->parent_id = iA;
A->aabb = _logic_abb_merge(B->aabb, G->aabb);
C->aabb = _logic_abb_merge(A->aabb, F->aabb);
A->height = 1 + MAX(B->height, G->height);
C->height = 1 + MAX(A->height, F->height);
}
else {
C->children[1] = iG;
A->children[1] = iF;
F->parent_id = iA;
A->aabb = _logic_abb_merge(B->aabb, F->aabb);
C->aabb = _logic_abb_merge(A->aabb, G->aabb);
A->height = 1 + MAX(B->height, F->height);
C->height = 1 + MAX(A->height, G->height);
}
return iC;
}
// B is higher, promote B
else if (balance < -1) {
int32_t iD = B->children[0];
int32_t iE = B->children[1];
TNode *D = &_nodes[iD];
TNode *E = &_nodes[iE];
// grandParent point to B
if (A->parent_id != BVHCommon::INVALID) {
if (_nodes[A->parent_id].children[0] == iA) {
_nodes[A->parent_id].children[0] = iB;
} else {
_nodes[A->parent_id].children[1] = iB;
}
}
else {
// check this .. seems dodgy
change_root_node(iB, p_tree_id);
}
// Swap A and B
B->children[1] = iA;
B->parent_id = A->parent_id;
A->parent_id = iB;
// Finish rotation
if (D->height > E->height) {
B->children[0] = iD;
A->children[0] = iE;
E->parent_id = iA;
A->aabb = _logic_abb_merge(C->aabb, E->aabb);
B->aabb = _logic_abb_merge(A->aabb, D->aabb);
A->height = 1 + MAX(C->height, E->height);
B->height = 1 + MAX(A->height, D->height);
}
else {
B->children[0] = iE;
A->children[0] = iD;
D->parent_id = iA;
A->aabb = _logic_abb_merge(C->aabb, D->aabb);
B->aabb = _logic_abb_merge(A->aabb, E->aabb);
A->height = 1 + MAX(C->height, D->height);
B->height = 1 + MAX(A->height, E->height);
}
return iB;
}
return iA;
}
// either choose an existing node to add item to, or create a new node and return this
uint32_t _logic_choose_item_add_node(uint32_t p_node_id, const BVHABB_CLASS &p_aabb) {
while (true) {
BVH_ASSERT(p_node_id != BVHCommon::INVALID);
TNode &tnode = _nodes[p_node_id];
if (tnode.is_leaf()) {
// if a leaf, and non full, use this to add to
if (!node_is_leaf_full(tnode)) {
return p_node_id;
}
// else split the leaf, and use one of the children to add to
return split_leaf(p_node_id, p_aabb);
}
// this should not happen???
// is still happening, need to debug and find circumstances. Is not that serious
// but would be nice to prevent. I think it only happens with the root node.
if (tnode.num_children == 1) {
WARN_PRINT_ONCE("BVH::recursive_choose_item_add_node, node with 1 child, recovering");
p_node_id = tnode.children[0];
} else {
BVH_ASSERT(tnode.num_children == 2);
TNode &childA = _nodes[tnode.children[0]];
TNode &childB = _nodes[tnode.children[1]];
int which = p_aabb.select_by_proximity(childA.aabb, childB.aabb);
p_node_id = tnode.children[which];
}
}
}