| 20 |
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|
| 21 |
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int |
| 22 |
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npixels(vp, hr, vr, hp, bi) /* compute appropriate number to evaluate */ |
| 23 |
< |
VIEW *vp; |
| 23 |
> |
register VIEW *vp; |
| 24 |
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int hr, vr; |
| 25 |
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HOLO *hp; |
| 26 |
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int bi; |
| 27 |
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{ |
| 28 |
< |
static VIEW vdo, vlast; |
| 29 |
< |
static HOLO *hplast; |
| 28 |
> |
VIEW vrev; |
| 29 |
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GCOORD gc[2]; |
| 30 |
< |
FVECT cp[4]; |
| 31 |
< |
FVECT ip[4]; |
| 33 |
< |
double d; |
| 30 |
> |
FVECT cp[4], ip[4]; |
| 31 |
> |
double af, ab; |
| 32 |
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register int i; |
| 33 |
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/* compute cell corners in image */ |
| 34 |
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if (!hdbcoord(gc, hp, bi)) |
| 35 |
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error(CONSISTENCY, "bad beam index in npixels"); |
| 36 |
< |
/* has holodeck or view changed? */ |
| 37 |
< |
if (hp != hplast || bcmp((char *)vp, (char *)&vlast, sizeof(VIEW))) { |
| 38 |
< |
copystruct(&vdo, vp); |
| 39 |
< |
if (sect_behind(hp, &vdo)) { /* reverse view sense */ |
| 40 |
< |
vdo.vdir[0] = -vdo.vdir[0]; |
| 41 |
< |
vdo.vdir[1] = -vdo.vdir[1]; |
| 44 |
< |
vdo.vdir[2] = -vdo.vdir[2]; |
| 45 |
< |
setview(&vdo); |
| 36 |
> |
hdcell(cp, hp, gc+1); /* find cell on front image */ |
| 37 |
> |
for (i = 0; i < 4; i++) { |
| 38 |
> |
viewloc(ip[i], vp, cp[i]); |
| 39 |
> |
if (ip[i][2] < 0.) { |
| 40 |
> |
af = 0; |
| 41 |
> |
goto getback; |
| 42 |
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} |
| 43 |
< |
hplast = hp; |
| 44 |
< |
copystruct(&vlast, vp); |
| 43 |
> |
ip[i][0] *= (double)hr; /* scale by resolution */ |
| 44 |
> |
ip[i][1] *= (double)vr; |
| 45 |
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} |
| 46 |
< |
hdcell(cp, hp, gc+1); /* find cell on image */ |
| 46 |
> |
/* compute front area */ |
| 47 |
> |
af = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) - |
| 48 |
> |
(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]); |
| 49 |
> |
af += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) - |
| 50 |
> |
(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]); |
| 51 |
> |
if (af >= 0) af *= 0.5; |
| 52 |
> |
else af *= -0.5; |
| 53 |
> |
getback: |
| 54 |
> |
copystruct(&vrev, vp); /* compute reverse view */ |
| 55 |
> |
for (i = 0; i < 3; i++) { |
| 56 |
> |
vrev.vdir[i] = -vp->vdir[i]; |
| 57 |
> |
vrev.vup[i] = -vp->vup[i]; |
| 58 |
> |
vrev.hvec[i] = -vp->hvec[i]; |
| 59 |
> |
vrev.vvec[i] = -vp->vvec[i]; |
| 60 |
> |
} |
| 61 |
> |
hdcell(cp, hp, gc); /* find cell on back image */ |
| 62 |
|
for (i = 0; i < 4; i++) { |
| 63 |
< |
viewloc(ip[i], &vdo, cp[i]); |
| 63 |
> |
viewloc(ip[i], &vrev, cp[i]); |
| 64 |
|
if (ip[i][2] < 0.) |
| 65 |
< |
return(0); |
| 65 |
> |
return((int)(af + 0.5)); |
| 66 |
|
ip[i][0] *= (double)hr; /* scale by resolution */ |
| 67 |
|
ip[i][1] *= (double)vr; |
| 68 |
|
} |
| 69 |
< |
/* compute quad area */ |
| 70 |
< |
d = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) - |
| 69 |
> |
/* compute back area */ |
| 70 |
> |
ab = (ip[1][0]-ip[0][0])*(ip[2][1]-ip[0][1]) - |
| 71 |
|
(ip[2][0]-ip[0][0])*(ip[1][1]-ip[0][1]); |
| 72 |
< |
d += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) - |
| 72 |
> |
ab += (ip[2][0]-ip[3][0])*(ip[1][1]-ip[3][1]) - |
| 73 |
|
(ip[1][0]-ip[3][0])*(ip[2][1]-ip[3][1]); |
| 74 |
< |
if (d < 0) |
| 75 |
< |
d = -d; |
| 76 |
< |
/* round off result */ |
| 77 |
< |
return((int)(.5*d+.5)); |
| 74 |
> |
if (ab >= 0) ab *= 0.5; |
| 75 |
> |
else ab *= -0.5; |
| 76 |
> |
/* round off smaller area */ |
| 77 |
> |
if (af <= ab) |
| 78 |
> |
return((int)(af + 0.5)); |
| 79 |
> |
return((int)(ab + 0.5)); |
| 80 |
|
} |
| 81 |
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|
| 82 |
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|
