339 lines
6.5 KiB
C
339 lines
6.5 KiB
C
/*
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Copyright (C) 2015-2019 Parallel Realities
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "quadtree.h"
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static Entity **candidates;
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static int cIndex;
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static int cCapacity;
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static int getIndex(Quadtree *root, int x, int y, int w, int h);
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static void removeEntity(Entity *e, Quadtree *root);
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static int candidatesComparator(const void *a, const void *b);
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static void getAllEntsWithinNode(int x, int y, int w, int h, Entity *ignore, Quadtree *root);
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static void destroyQuadtreeNode(Quadtree *root);
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static void resizeQTEntCapacity(Quadtree *root);
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static void resizeCandidates(void);
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void initQuadtree(Quadtree *root)
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{
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Quadtree *node;
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int i, w, h;
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/* entire battlefield */
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if (root->depth == 0)
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{
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root->w = BATTLE_AREA_WIDTH;
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root->h = BATTLE_AREA_HEIGHT;
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root->capacity = QT_INITIAL_CAPACITY;
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root->ents = malloc(sizeof(Entity*) * root->capacity);
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memset(root->ents, 0, sizeof(Entity*) * root->capacity);
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cIndex = 0;
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cCapacity = QT_INITIAL_CAPACITY;
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candidates = malloc(sizeof(Entity*) * cCapacity);
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memset(candidates, 0, sizeof(Entity*) * cCapacity);
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}
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w = root->w / 2;
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h = root->h / 2;
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if (root->depth + 1 < QT_MAX_DEPTH)
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{
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for (i = 0 ; i < 4 ; i++)
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{
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node = malloc(sizeof(Quadtree));
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memset(node, 0, sizeof(Quadtree));
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root->node[i] = node;
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node->depth = root->depth + 1;
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node->capacity = QT_INITIAL_CAPACITY;
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node->ents = malloc(sizeof(Entity*) * node->capacity);
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memset(node->ents, 0, sizeof(Entity*) * node->capacity);
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if (i == 0)
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{
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node->x = root->x;
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node->y = root->y;
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node->w = w;
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node->h = h;
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}
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else if (i == 1)
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{
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node->x = root->x + w;
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node->y = root->y;
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node->w = w;
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node->h = h;
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}
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else if (i == 2)
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{
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node->x = root->x;
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node->y = root->y + h;
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node->w = w;
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node->h = h;
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}
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else
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{
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node->x = root->x + w;
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node->y = root->y + h;
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node->w = w;
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node->h = h;
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}
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initQuadtree(node);
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}
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}
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}
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void addToQuadtree(Entity *e, Quadtree *root)
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{
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int index;
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root->addedTo = 1;
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if (root->node[0])
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{
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index = getIndex(root, e->x - (e->w / 2), e->y - (e->h / 2), e->w, e->h);
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if (index != -1)
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{
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addToQuadtree(e, root->node[index]);
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return;
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}
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}
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if (root->numEnts == root->capacity)
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{
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resizeQTEntCapacity(root);
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}
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root->ents[root->numEnts++] = e;
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}
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static void resizeQTEntCapacity(Quadtree *root)
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{
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int n;
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n = root->capacity + QT_INITIAL_CAPACITY;
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SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_DEBUG, "Resizing QT node: %d -> %d", root->capacity, n);
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root->ents = resize(root->ents, sizeof(Entity*) * root->capacity, sizeof(Entity*) * n);
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root->capacity = n;
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}
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static int getIndex(Quadtree *root, int x, int y, int w, int h)
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{
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int index = -1;
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int verticalMidpoint = root->x + (root->w / 2);
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int horizontalMidpoint = root->y + (root->h / 2);
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int topQuadrant = (y < horizontalMidpoint && y + h < horizontalMidpoint);
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int bottomQuadrant = (y > horizontalMidpoint);
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if (x < verticalMidpoint && x + w < verticalMidpoint)
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{
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if (topQuadrant)
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{
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index = 0;
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}
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else if (bottomQuadrant)
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{
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index = 2;
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}
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}
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else if (x > verticalMidpoint)
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{
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if (topQuadrant)
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{
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index = 1;
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}
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else if (bottomQuadrant)
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{
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index = 3;
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}
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}
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return index;
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}
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void removeFromQuadtree(Entity *e, Quadtree *root)
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{
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int index;
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if (root->addedTo)
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{
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if (root->node[0])
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{
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index = getIndex(root, e->x - (e->w / 2), e->y - (e->h / 2), e->w, e->h);
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if (index != -1)
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{
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removeFromQuadtree(e, root->node[index]);
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return;
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}
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}
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removeEntity(e, root);
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if (root->numEnts == 0)
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{
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root->addedTo = 0;
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if (root->node[0])
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{
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root->addedTo = root->node[0]->addedTo || root->node[1]->addedTo || root->node[2]->addedTo || root->node[3]->addedTo;
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}
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}
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}
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}
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static void removeEntity(Entity *e, Quadtree *root)
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{
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int i, n;
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n = root->numEnts;
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for (i = 0 ; i < root->capacity ; i++)
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{
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if (root->ents[i] == e)
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{
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root->ents[i] = NULL;
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root->numEnts--;
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}
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}
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qsort(root->ents, n, sizeof(Entity*), candidatesComparator);
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}
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Entity **getAllEntsWithin(int x, int y, int w, int h, Entity *ignore)
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{
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cIndex = 0;
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memset(candidates, 0, sizeof(Entity*) * cCapacity);
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getAllEntsWithinNode(x, y, w, h, ignore, &battle.quadtree);
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return candidates;
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}
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Entity **getAllEntsInRadius(int x, int y, int radius, Entity *ignore)
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{
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return getAllEntsWithin(x - radius / 2, y - radius / 2, radius, radius, ignore);
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}
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static void getAllEntsWithinNode(int x, int y, int w, int h, Entity *ignore, Quadtree *root)
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{
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int index, i;
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if (root->addedTo)
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{
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if (root->node[0])
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{
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index = getIndex(root, x, y, w, h);
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if (index != -1)
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{
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getAllEntsWithinNode(x, y, w, h, ignore, root->node[index]);
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}
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else
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{
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for (i = 0 ; i < 4 ; i++)
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{
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getAllEntsWithinNode(x, y, w, h, ignore, root->node[i]);
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}
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}
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}
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for (i = 0 ; i < root->numEnts ; i++)
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{
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candidates[cIndex++] = root->ents[i];
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if (cIndex == cCapacity)
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{
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resizeCandidates();
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}
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}
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}
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}
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static void resizeCandidates(void)
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{
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int n;
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n = cCapacity + QT_INITIAL_CAPACITY;
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SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_DEBUG, "Resizing candidates: %d -> %d", cCapacity, n);
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candidates = resize(candidates, sizeof(Entity*) * cCapacity, sizeof(Entity*) * n);
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cCapacity = n;
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}
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void destroyQuadtree(void)
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{
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destroyQuadtreeNode(&battle.quadtree);
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if (candidates)
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{
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free(candidates);
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candidates = NULL;
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}
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}
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static void destroyQuadtreeNode(Quadtree *root)
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{
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int i;
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free(root->ents);
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root->ents = NULL;
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if (root->node[0])
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{
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for (i = 0 ; i < 4 ; i++)
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{
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destroyQuadtreeNode(root->node[i]);
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free(root->node[i]);
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root->node[i] = NULL;
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}
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}
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}
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static int candidatesComparator(const void *a, const void *b)
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{
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Entity *e1 = *((Entity**)a);
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Entity *e2 = *((Entity**)b);
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if (!e1)
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{
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return 1;
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}
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else if (!e2)
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{
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return -1;
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}
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else
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{
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return 0;
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}
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}
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