| 27 |
|
* 3 red grn blu |
| 28 |
|
* |
| 29 |
|
* The color is used for the transmission at normal incidence. |
| 30 |
< |
* To compute transmission (tn) from transmissivity (Tn) use: |
| 30 |
> |
* To compute transmissivity (tn) from transmittance (Tn) use: |
| 31 |
|
* |
| 32 |
|
* tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn |
| 33 |
|
* |
| 34 |
< |
* The transmission of standard 88% transmissivity glass is 0.96. |
| 34 |
> |
* The transmissivity of standard 88% transmittance 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 |
|
*/ |
| 46 |
|
OBJREC *m; |
| 47 |
|
register RAY *r; |
| 48 |
|
{ |
| 46 |
– |
double sqrt(), pow(); |
| 49 |
|
COLOR mcolor; |
| 50 |
|
double pdot; |
| 51 |
|
FVECT pnorm; |
| 52 |
< |
double cos2; |
| 52 |
> |
double rindex, cos2; |
| 53 |
|
COLOR trans, refl; |
| 54 |
< |
double d, r1; |
| 54 |
> |
double d, r1e, r1m; |
| 55 |
|
double transtest, transdist; |
| 56 |
|
RAY p; |
| 57 |
|
register int i; |
| 58 |
< |
|
| 59 |
< |
if (m->oargs.nfargs != 3) |
| 58 |
> |
/* check arguments */ |
| 59 |
> |
if (m->oargs.nfargs == 3) |
| 60 |
> |
rindex = RINDEX; /* default value of n */ |
| 61 |
> |
else if (m->oargs.nfargs == 4) |
| 62 |
> |
rindex = m->oargs.farg[3]; /* use their value */ |
| 63 |
> |
else |
| 64 |
|
objerror(m, USER, "bad arguments"); |
| 65 |
|
|
| 66 |
|
setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]); |
| 72 |
|
raytexture(r, m->omod); |
| 73 |
|
pdot = raynormal(pnorm, r); |
| 74 |
|
/* angular transmission */ |
| 75 |
< |
cos2 = sqrt( (1.0-1.0/RINDEX/RINDEX) + |
| 76 |
< |
pdot*pdot/(RINDEX*RINDEX) ); |
| 75 |
> |
cos2 = sqrt( (1.0-1.0/(rindex*rindex)) + |
| 76 |
> |
pdot*pdot/(rindex*rindex) ); |
| 77 |
|
setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2), |
| 78 |
|
pow(colval(mcolor,GRN), 1.0/cos2), |
| 79 |
|
pow(colval(mcolor,BLU), 1.0/cos2)); |
| 80 |
|
|
| 81 |
|
/* compute reflection */ |
| 82 |
< |
r1 = (pdot - RINDEX*cos2) / (pdot + RINDEX*cos2); |
| 83 |
< |
d = (1.0/pdot - RINDEX/cos2) / (1.0/pdot + RINDEX/cos2); |
| 84 |
< |
r1 = (r1*r1 + d*d) / 2.0; |
| 82 |
> |
r1e = (pdot - rindex*cos2) / (pdot + rindex*cos2); |
| 83 |
> |
r1e *= r1e; |
| 84 |
> |
r1m = (1.0/pdot - rindex/cos2) / (1.0/pdot + rindex/cos2); |
| 85 |
> |
r1m *= r1m; |
| 86 |
|
/* compute transmittance */ |
| 87 |
|
for (i = 0; i < 3; i++) { |
| 88 |
|
d = colval(mcolor, i); |
| 89 |
< |
colval(trans,i) = (1.0-r1)*(1.0-r1)*d / (1.0 - r1*r1*d*d); |
| 89 |
> |
colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d/(1.0-r1e*r1e*d*d); |
| 90 |
> |
colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d/(1.0-r1m*r1m*d*d); |
| 91 |
|
} |
| 92 |
|
/* transmitted ray */ |
| 93 |
|
if (rayorigin(&p, r, TRANS, bright(trans)) == 0) { |
| 94 |
|
if (!(r->crtype & SHADOW) && |
| 95 |
|
DOT(r->pert,r->pert) > FTINY*FTINY) { |
| 96 |
|
for (i = 0; i < 3; i++) /* perturb direction */ |
| 97 |
< |
p.rdir[i] = r->rdir[i] - r->pert[i]/RINDEX; |
| 98 |
< |
normalize(p.rdir); |
| 97 |
> |
p.rdir[i] = r->rdir[i] + |
| 98 |
> |
2.*(1.-rindex)*r->pert[i]; |
| 99 |
> |
if (normalize(p.rdir) == 0.0) { |
| 100 |
> |
objerror(m, WARNING, "bad perturbation"); |
| 101 |
> |
VCOPY(p.rdir, r->rdir); |
| 102 |
> |
} |
| 103 |
|
} else { |
| 104 |
|
VCOPY(p.rdir, r->rdir); |
| 105 |
|
transtest = 2; |
| 118 |
|
for (i = 0; i < 3; i++) { |
| 119 |
|
d = colval(mcolor, i); |
| 120 |
|
d *= d; |
| 121 |
< |
colval(refl,i) = r1 * (1.0 + (1.0-2.0*r1)*d) / (1.0 - r1*r1*d); |
| 121 |
> |
colval(refl,i) = .5*r1e*(1.0+(1.0-2.0*r1e)*d)/(1.0-r1e*r1e*d); |
| 122 |
> |
colval(refl,i) += .5*r1m*(1.0+(1.0-2.0*r1m)*d)/(1.0-r1m*r1m*d); |
| 123 |
|
} |
| 124 |
|
/* reflected ray */ |
| 125 |
|
if (rayorigin(&p, r, REFLECTED, bright(refl)) == 0) { |
