| 32 |
|
* tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn |
| 33 |
|
* |
| 34 |
|
* The transmission of standard 88% transmissivity glass is 0.96. |
| 35 |
+ |
* A refractive index other than the default can be used by giving |
| 36 |
+ |
* it as the fourth real argument. The above formula no longer applies. |
| 37 |
+ |
* |
| 38 |
|
* If we appear to hit the back side of the surface, then we |
| 39 |
|
* turn the normal around. |
| 40 |
|
*/ |
| 50 |
|
COLOR mcolor; |
| 51 |
|
double pdot; |
| 52 |
|
FVECT pnorm; |
| 53 |
< |
double cos2; |
| 53 |
> |
double rindex, cos2; |
| 54 |
|
COLOR trans, refl; |
| 55 |
|
double d, r1e, r1m; |
| 56 |
|
double transtest, transdist; |
| 57 |
|
RAY p; |
| 58 |
|
register int i; |
| 59 |
< |
|
| 60 |
< |
if (m->oargs.nfargs != 3) |
| 59 |
> |
/* check arguments */ |
| 60 |
> |
if (m->oargs.nfargs == 3) |
| 61 |
> |
rindex = RINDEX; /* default value of n */ |
| 62 |
> |
else if (m->oargs.nfargs == 4) |
| 63 |
> |
rindex = m->oargs.farg[3]; /* use their value */ |
| 64 |
> |
else |
| 65 |
|
objerror(m, USER, "bad arguments"); |
| 66 |
|
|
| 67 |
|
setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]); |
| 73 |
|
raytexture(r, m->omod); |
| 74 |
|
pdot = raynormal(pnorm, r); |
| 75 |
|
/* angular transmission */ |
| 76 |
< |
cos2 = sqrt( (1.0-1.0/RINDEX/RINDEX) + |
| 77 |
< |
pdot*pdot/(RINDEX*RINDEX) ); |
| 76 |
> |
cos2 = sqrt( (1.0-1.0/(rindex*rindex)) + |
| 77 |
> |
pdot*pdot/(rindex*rindex) ); |
| 78 |
|
setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2), |
| 79 |
|
pow(colval(mcolor,GRN), 1.0/cos2), |
| 80 |
|
pow(colval(mcolor,BLU), 1.0/cos2)); |
| 81 |
|
|
| 82 |
|
/* compute reflection */ |
| 83 |
< |
r1e = (pdot - RINDEX*cos2) / (pdot + RINDEX*cos2); |
| 83 |
> |
r1e = (pdot - rindex*cos2) / (pdot + rindex*cos2); |
| 84 |
|
r1e *= r1e; |
| 85 |
< |
r1m = (1.0/pdot - RINDEX/cos2) / (1.0/pdot + RINDEX/cos2); |
| 85 |
> |
r1m = (1.0/pdot - rindex/cos2) / (1.0/pdot + rindex/cos2); |
| 86 |
|
r1m *= r1m; |
| 87 |
|
/* compute transmittance */ |
| 88 |
|
for (i = 0; i < 3; i++) { |
| 95 |
|
if (!(r->crtype & SHADOW) && |
| 96 |
|
DOT(r->pert,r->pert) > FTINY*FTINY) { |
| 97 |
|
for (i = 0; i < 3; i++) /* perturb direction */ |
| 98 |
< |
p.rdir[i] = r->rdir[i] - r->pert[i]/RINDEX; |
| 98 |
> |
p.rdir[i] = r->rdir[i] - r->pert[i]/rindex; |
| 99 |
|
normalize(p.rdir); |
| 100 |
|
} else { |
| 101 |
|
VCOPY(p.rdir, r->rdir); |
