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#include "collision.h"
//****************************************************************************
void init_sp_bb( apvector<spr_mask> & mask_list )
// This function initializes the bounding box used to do the initial collision detection
{
int i,c,z;
for ( i =0; i < mask_list.length(); i++)
{
mask_list[i].bb_height=0;
mask_list[i].bb_width=0;
mask_list[i].max_chunk=0;
for ( c = 0; c < NUM_Y; c++ )
for ( z = 0; z < NUM_CHUNKS; z++)
mask_list[i].sp_mask[c][z]=0;
}
}
//****************************************************************************
void mk_spr_mask (BITMAP *s3, spr_mask & mask)
// This function produces the masks that do the pixel perfect collision detection
{
int bb_height=0;
int bb_width=0;
int x1, y1, z;
int p;
for (y1=0; y1<NUM_Y; y1++)
{
for(z=0; z<NUM_CHUNKS; z++)
{
for (x1=(z*32); x1<(z*32+32); x1++)
{
p=getpixel(s3,x1,y1);
if (p>0)
{
if (z> mask.max_chunk)
( mask.max_chunk = z);
if (y1>bb_height)
bb_height=y1;
if (x1>bb_width)
bb_width=x1;
mask.sp_mask[y1][z]+=1<<(z*32+32-1-x1);
}
}
}
}
mask.bb_height=bb_height;
mask.bb_width=bb_width;
}
//****************************************************************************
int check_ppcollision (const spr_mask & mask1 , int spr1x, int spr1y, const spr_mask & mask2, int spr2x, int spr2y)
// this is the function that actually checks collisions
{
int dx1, dx2, dy1, dy2, ddy1, ddy2;
int spr1_chunk, spr2_chunk;
int dx1_chunk, dx2_chunk;
if ((spr1x>spr2x+ mask2.bb_width) || (spr2x > spr1x + mask1.bb_width) ||
(spr1y>spr2y+ mask2.bb_height) || (spr2y> spr1y + mask1.bb_height))
{
return 0;
}
else
{
if (spr1x>spr2x)
{
dx1=0;
dx2=spr1x-spr2x;
}
else
{
dx1=spr2x-spr1x;
dx2=0;
}
if (spr1y>spr2y)
{
dy1=0;
dy2=spr1y-spr2y;
}
else
{
dy1=(spr2y-spr1y);
dy2=0;
}
spr1_chunk = dx1 / 32;
spr2_chunk = dx2 / 32;
dx1_chunk = dx1 - (32 * spr1_chunk);
dx2_chunk = dx2 - (32 * spr2_chunk);
while((spr1_chunk <= mask1.max_chunk) & (spr2_chunk <= mask2.max_chunk))
{
ddy1 = dy1;
ddy2 = dy2;
while((ddy1<=mask1.bb_height)&&(ddy2<=mask2.bb_height))
{
if ((mask1.sp_mask[ddy1][spr1_chunk]<<dx1_chunk) & (mask2.sp_mask[ddy2][spr2_chunk]<<dx2_chunk))
return 1;
ddy1++;
ddy2++;
}
if((!dx1_chunk) && (!dx2_chunk))
{
spr1_chunk++;
spr2_chunk++;
}
else if(!dx1_chunk)
{
spr2_chunk++;
dx1_chunk = 32 - dx2_chunk;
dx2_chunk = 0;
}
else if(!dx2_chunk)
{
spr1_chunk++;
dx2_chunk = 32 - dx1_chunk;
dx1_chunk = 0;
}
}
return 0;
}
}
//****************************************************************************
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