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#include <vecmath.h>
#include <physics.h>
#include <stdlib.h>
#include <string.h>
#include "dat.h"
#define BUCKETS 0x10000 /* must be a power of 2 */
#define BUCKETMASK (BUCKETS - 1)
#define PHI 1.618033988749895
#define HMUL (int)(BUCKETS / PHI)
static int hash(int a);
static void makeblockmap(Body *b);
static BlockmapNode *allocnode(void);
static BlockmapNode nodes[(1 << 20)];
static int nodesi;
static BlockmapNode *lists[BUCKETS];
void
phxmakeblkmap()
{
nodesi = 0;
for(int i = 0; i < BUCKETS; i++)
lists[i] = NULL;
for(int i = 0; i < phxbodypoolsize; i++) {
Body *b = phxbodypool + i;
if(!b->active)
continue;
makeblockmap(b);
}
}
void
makeblockmap(Body *b)
{
BlockmapNode *n;
if((n = allocnode()) == NULL)
return;
n->id = b - phxbodypool;
n->next = NULL;
int mapx = (int)floorf(b->pos[0] / BLOCK_SIZE);
int mapy = (int)floorf(b->pos[1] / BLOCK_SIZE);
int h = hash(mapx + hash(mapy));
n->next = lists[h];
lists[h] = n;
}
int
hash(int a)
{
return (a * HMUL) & BUCKETMASK;
}
BlockmapNode *
allocnode(void)
{
if(nodesi == (sizeof(nodes) / sizeof(nodes[0])))
return NULL;
return nodes + nodesi++;
}
BlockmapNode *
phxnodelist(float x, float y)
{
int mapx = (int)floorf(x / BLOCK_SIZE);
int mapy = (int)floorf(y / BLOCK_SIZE);
int h = hash(mapx + hash(mapy));
return lists[h];
}
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