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Quadtree.

This commit is contained in:
Steve 2018-01-21 11:31:53 +00:00
parent abfd6df63b
commit 4fd1abd52d
5 changed files with 394 additions and 0 deletions
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1
common.mk
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@ -15,6 +15,7 @@ OBJS += hud.o
OBJS += init.o input.o io.o OBJS += init.o input.o io.o
OBJS += lookup.o OBJS += lookup.o
OBJS += main.o map.o maths.o OBJS += main.o map.o maths.o
OBJS += quadtree.o
OBJS += text.o textures.o title.o OBJS += text.o textures.o title.o
OBJS += util.o OBJS += util.o
OBJS += widgets.o OBJS += widgets.o

12
src/structs.h
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@ -20,6 +20,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
typedef struct Texture Texture; typedef struct Texture Texture;
typedef struct Lookup Lookup; typedef struct Lookup Lookup;
typedef struct Quadtree Quadtree;
typedef struct Entity Entity; typedef struct Entity Entity;
typedef struct { typedef struct {
@ -128,6 +129,17 @@ typedef struct {
SDL_Rect bounds; SDL_Rect bounds;
} Map; } Map;
struct Quadtree {
int depth;
int x, y, w, h;
Entity **ents;
int capacity;
int numEnts;
int addedTo;
Quadtree *node[4];
};
typedef struct { typedef struct {
Map map; Map map;
Quadtree quadtree;
} World; } World;

15
src/util/util.c
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@ -47,3 +47,18 @@ char *timeToString(long millis, int showHours)
return TIME; return TIME;
} }
void *resize(void *array, int oldSize, int newSize)
{
void **newArray;
int copySize;
copySize = newSize > oldSize ? oldSize : newSize;
newArray = malloc(newSize);
memset(newArray, 0, newSize);
memcpy(newArray, array, copySize);
free(array);
return newArray;
}

338
src/world/quadtree.c Normal file
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@ -0,0 +1,338 @@
/*
Copyright (C) 2018 Parallel Realities
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "quadtree.h"
static Entity **candidates;
static int cIndex;
static int cCapacity;
static int getIndex(Quadtree *root, int x, int y, int w, int h);
static void removeEntity(Entity *e, Quadtree *root);
static int candidatesComparator(const void *a, const void *b);
static void getAllEntsWithinNode(int x, int y, int w, int h, Entity *ignore, Quadtree *root);
static void destroyQuadtreeNode(Quadtree *root);
static void resizeQTEntCapacity(Quadtree *root);
static void resizeCandidates(void);
void initQuadtree(Quadtree *root)
{
Quadtree *node;
int i, w, h;
/* entire map */
if (root->depth == 0)
{
root->w = MAP_WIDTH * MAP_TILE_SIZE;
root->h = MAP_HEIGHT * MAP_TILE_SIZE;
root->capacity = QT_INITIAL_CAPACITY;
root->ents = malloc(sizeof(Entity*) * root->capacity);
memset(root->ents, 0, sizeof(Entity*) * root->capacity);
cIndex = 0;
cCapacity = QT_INITIAL_CAPACITY;
candidates = malloc(sizeof(Entity*) * cCapacity);
memset(candidates, 0, sizeof(Entity*) * cCapacity);
}
w = root->w / 2;
h = root->h / 2;
if (root->depth + 1 < QT_MAX_DEPTH)
{
for (i = 0 ; i < 4 ; i++)
{
node = malloc(sizeof(Quadtree));
memset(node, 0, sizeof(Quadtree));
root->node[i] = node;
node->depth = root->depth + 1;
node->capacity = QT_INITIAL_CAPACITY;
node->ents = malloc(sizeof(Entity*) * node->capacity);
memset(node->ents, 0, sizeof(Entity*) * node->capacity);
if (i == 0)
{
node->x = root->x;
node->y = root->y;
node->w = w;
node->h = h;
}
else if (i == 1)
{
node->x = root->x + w;
node->y = root->y;
node->w = w;
node->h = h;
}
else if (i == 2)
{
node->x = root->x;
node->y = root->y + h;
node->w = w;
node->h = h;
}
else
{
node->x = root->x + w;
node->y = root->y + h;
node->w = w;
node->h = h;
}
initQuadtree(node);
}
}
}
void addToQuadtree(Entity *e, Quadtree *root)
{
int index;
root->addedTo = 1;
if (root->node[0])
{
index = getIndex(root, e->x - (e->w / 2), e->y - (e->h / 2), e->w, e->h);
if (index != -1)
{
addToQuadtree(e, root->node[index]);
return;
}
}
if (root->numEnts == root->capacity)
{
resizeQTEntCapacity(root);
}
root->ents[root->numEnts++] = e;
}
static void resizeQTEntCapacity(Quadtree *root)
{
int n;
n = root->capacity + QT_INITIAL_CAPACITY;
SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_DEBUG, "Resizing QT node: %d -> %d", root->capacity, n);
root->ents = resize(root->ents, sizeof(Entity*) * root->capacity, sizeof(Entity*) * n);
root->capacity = n;
}
static int getIndex(Quadtree *root, int x, int y, int w, int h)
{
int index = -1;
int verticalMidpoint = root->x + (root->w / 2);
int horizontalMidpoint = root->y + (root->h / 2);
int topQuadrant = (y < horizontalMidpoint && y + h < horizontalMidpoint);
int bottomQuadrant = (y > horizontalMidpoint);
if (x < verticalMidpoint && x + w < verticalMidpoint)
{
if (topQuadrant)
{
index = 0;
}
else if (bottomQuadrant)
{
index = 2;
}
}
else if (x > verticalMidpoint)
{
if (topQuadrant)
{
index = 1;
}
else if (bottomQuadrant)
{
index = 3;
}
}
return index;
}
void removeFromQuadtree(Entity *e, Quadtree *root)
{
int index;
if (root->addedTo)
{
if (root->node[0])
{
index = getIndex(root, e->x - (e->w / 2), e->y - (e->h / 2), e->w, e->h);
if (index != -1)
{
removeFromQuadtree(e, root->node[index]);
return;
}
}
removeEntity(e, root);
if (root->numEnts == 0)
{
root->addedTo = 0;
if (root->node[0])
{
root->addedTo = root->node[0]->addedTo || root->node[1]->addedTo || root->node[2]->addedTo || root->node[3]->addedTo;
}
}
}
}
static void removeEntity(Entity *e, Quadtree *root)
{
int i, n;
n = root->numEnts;
for (i = 0 ; i < root->capacity ; i++)
{
if (root->ents[i] == e)
{
root->ents[i] = NULL;
root->numEnts--;
}
}
qsort(root->ents, n, sizeof(Entity*), candidatesComparator);
}
Entity **getAllEntsWithin(int x, int y, int w, int h, Entity *ignore)
{
cIndex = 0;
memset(candidates, 0, sizeof(Entity*) * cCapacity);
getAllEntsWithinNode(x, y, w, h, ignore, &world.quadtree);
return candidates;
}
Entity **getAllEntsInRadius(int x, int y, int radius, Entity *ignore)
{
return getAllEntsWithin(x - radius / 2, y - radius / 2, radius, radius, ignore);
}
static void getAllEntsWithinNode(int x, int y, int w, int h, Entity *ignore, Quadtree *root)
{
int index, i;
if (root->addedTo)
{
if (root->node[0])
{
index = getIndex(root, x, y, w, h);
if (index != -1)
{
getAllEntsWithinNode(x, y, w, h, ignore, root->node[index]);
}
else
{
for (i = 0 ; i < 4 ; i++)
{
getAllEntsWithinNode(x, y, w, h, ignore, root->node[i]);
}
}
}
for (i = 0 ; i < root->numEnts ; i++)
{
candidates[cIndex++] = root->ents[i];
if (cIndex == cCapacity)
{
resizeCandidates();
}
}
}
}
static void resizeCandidates(void)
{
int n;
n = cCapacity + QT_INITIAL_CAPACITY;
SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_DEBUG, "Resizing candidates: %d -> %d", cCapacity, n);
candidates = resize(candidates, sizeof(Entity*) * cCapacity, sizeof(Entity*) * n);
cCapacity = n;
}
void destroyQuadtree(void)
{
destroyQuadtreeNode(&world.quadtree);
if (candidates)
{
free(candidates);
candidates = NULL;
}
}
static void destroyQuadtreeNode(Quadtree *root)
{
int i;
free(root->ents);
root->ents = NULL;
if (root->node[0])
{
for (i = 0 ; i < 4 ; i++)
{
destroyQuadtreeNode(root->node[i]);
free(root->node[i]);
root->node[i] = NULL;
}
}
}
static int candidatesComparator(const void *a, const void *b)
{
Entity *e1 = *((Entity**)a);
Entity *e2 = *((Entity**)b);
if (!e1)
{
return 1;
}
else if (!e2)
{
return -1;
}
else
{
return 0;
}
}

28
src/world/quadtree.h Normal file
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@ -0,0 +1,28 @@
/*
Copyright (C) 2018 Parallel Realities
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "../common.h"
#define QT_MAX_DEPTH 5
#define QT_INITIAL_CAPACITY 8
extern void *resize(void *array, int oldSize, int newSize);
extern World world;