BMAP* grain1;
BMAP* grain2;
BMAP* grain3;
BMAP* grain4;
function GSTBmap_Extract(){
   BMAP* bmpTemp = "grain.png";
   grain1 = bmap_createblack(512, 512, 32); // create an empty bmap
   bmap_blitpart(grain1, bmpTemp, vector(0,0,0), vector(512,512,0), vector(0,0,0),vector(512,512,0));
   grain2 = bmap_createblack(512, 512, 32); // create an empty bmap
   bmap_blitpart(grain2, bmpTemp, vector(0,0,0), vector(512,512,0), vector(513,0,0),vector(512,512,0));
   grain3 = bmap_createblack(512, 512, 32); // create an empty bmap
   bmap_blitpart(grain3, bmpTemp, vector(0,0,0), vector(512,512,0), vector(1026,0,0),vector(512,512,0));
   grain4 = bmap_createblack(512, 512, 32); // create an empty bmap
   bmap_blitpart(grain4, bmpTemp, vector(0,0,0), vector(512,512,0), vector(0,513,0),vector(512,512,0));
   bmap_purge(bmpTemp);
}