| 122 |
|
float *zbar[MAXDIV+1]; /* z values */ |
| 123 |
|
int ypos; /* current scanline */ |
| 124 |
|
int ystep; /* current y step size */ |
| 125 |
+ |
int hstep; /* h step size */ |
| 126 |
|
int zfd; |
| 127 |
|
COLOR *colptr; |
| 128 |
|
float *zptr; |
| 173 |
|
#endif |
| 174 |
|
signal(SIGALRM, report); |
| 175 |
|
ypos = vresolu-1 - i; |
| 176 |
< |
fillscanline(scanbar[0], zbar[0], hresolu, ypos, psample); |
| 177 |
< |
ystep = psample; |
| 176 |
> |
hstep = (psample*140+49)/99; /* quincunx sampling */ |
| 177 |
> |
ystep = (psample*99+70)/140; |
| 178 |
> |
fillscanline(scanbar[0], zbar[0], hresolu, ypos, hstep); |
| 179 |
|
/* compute scanlines */ |
| 180 |
|
for (ypos -= ystep; ypos > -ystep; ypos -= ystep) { |
| 181 |
|
/* bottom adjust? */ |
| 190 |
|
zbar[ystep] = zbar[0]; |
| 191 |
|
zbar[0] = zptr; |
| 192 |
|
/* fill base line */ |
| 193 |
< |
fillscanline(scanbar[0], zbar[0], hresolu, ypos, psample); |
| 193 |
> |
fillscanline(scanbar[0], zbar[0], hresolu, ypos, hstep); |
| 194 |
|
/* fill bar */ |
| 195 |
|
fillscanbar(scanbar, zbar, hresolu, ypos, ystep); |
| 196 |
|
/* write it out */ |
| 245 |
|
register float *zline; |
| 246 |
|
int xres, y, xstep; |
| 247 |
|
{ |
| 248 |
+ |
static int nc = 0; /* number of calls */ |
| 249 |
|
int b = xstep; |
| 250 |
|
double z; |
| 251 |
|
register int i; |
| 252 |
|
|
| 253 |
|
z = pixvalue(scanline[0], 0, y); |
| 254 |
|
if (zline) zline[0] = z; |
| 255 |
< |
|
| 256 |
< |
for (i = xstep; i < xres-1+xstep; i += xstep) { |
| 255 |
> |
/* zig-zag start for quincunx pattern */ |
| 256 |
> |
for (i = nc++ & 1 ? xstep/2 : xstep; i < xres-1+xstep; i += xstep) { |
| 257 |
|
if (i >= xres) { |
| 258 |
|
xstep += xres-1-i; |
| 259 |
|
i = xres-1; |
