Excerpt from slab6.c: savevox()

slab6.c

void savevox (char *filnam)
{
	FILE *fil;
	long i, x, y, z;
	voxtype *vptr, *vptr2;

	optimizexdimen();
	optimizeydimen();
	optimizezdimen();

	if (!(fil = fopen(filnam,"wb"))) return;

	fwrite(&xsiz,4,1,fil);
	fwrite(&ysiz,4,1,fil);
	fwrite(&zsiz,4,1,fil);
	vptr = voxdata;
	for(x=0;x<xsiz;x++)
		for(y=0;y<ysiz;y++)
		{
			vptr2 = &vptr[ylen[x][y]];
			for(z=0;z<zsiz;z++)
			{
				if ((vptr < vptr2) && (vptr->z == z))
					{ fputc(vptr->col,fil); vptr++; }
				else
				{
					i = (x*MAXYSIZ+y)*BUFZSIZ+z;
					if (!(vbit[i>>5]&(1<<i))) fputc(0,fil);
					else fputc(255,fil);
				}
			}
		}
	fwrite(fipalette,768,1,fil);
	fclose(fil);
}