150 |
|
makespot(m) /* make a spotlight */ |
151 |
|
register OBJREC *m; |
152 |
|
{ |
153 |
– |
extern double cos(); |
153 |
|
register SPOT *ns; |
154 |
|
|
155 |
|
if ((ns = (SPOT *)malloc(sizeof(SPOT))) == NULL) |
227 |
|
co = getcone(op, 0); |
228 |
|
VCOPY(nvec, co->ad); |
229 |
|
return(DOT(nvec, CO_P0(co))); |
230 |
+ |
} |
231 |
+ |
|
232 |
+ |
|
233 |
+ |
commonspot(sp1, sp2, org) /* set sp1 to intersection of sp1 and sp2 */ |
234 |
+ |
register SPOT *sp1, *sp2; |
235 |
+ |
FVECT org; |
236 |
+ |
{ |
237 |
+ |
FVECT cent; |
238 |
+ |
double rad2, cos1, cos2; |
239 |
+ |
|
240 |
+ |
cos1 = 1. - sp1->siz/(2.*PI); |
241 |
+ |
cos2 = 1. - sp2->siz/(2.*PI); |
242 |
+ |
if (sp2->siz >= 2.*PI-FTINY) /* BIG, just check overlap */ |
243 |
+ |
return(DOT(sp1->aim,sp2->aim) >= cos1*cos2 - |
244 |
+ |
sqrt((1.-cos1*cos1)*(1.-cos2*cos2))); |
245 |
+ |
/* compute and check disks */ |
246 |
+ |
rad2 = intercircle(cent, sp1->aim, sp2->aim, |
247 |
+ |
1./(cos1*cos1) - 1., 1./(cos2*cos2) - 1.); |
248 |
+ |
if (rad2 <= FTINY || normalize(cent) == 0.) |
249 |
+ |
return(0); |
250 |
+ |
VCOPY(sp1->aim, cent); |
251 |
+ |
sp1->siz = 2.*PI*(1. - 1./sqrt(1.+rad2)); |
252 |
+ |
return(1); |
253 |
+ |
} |
254 |
+ |
|
255 |
+ |
|
256 |
+ |
commonbeam(sp1, sp2, dir) /* set sp1 to intersection of sp1 and sp2 */ |
257 |
+ |
register SPOT *sp1, *sp2; |
258 |
+ |
FVECT dir; |
259 |
+ |
{ |
260 |
+ |
FVECT cent, c1, c2; |
261 |
+ |
double rad2, d; |
262 |
+ |
register int i; |
263 |
+ |
/* move centers to common plane */ |
264 |
+ |
d = DOT(sp1->aim, dir); |
265 |
+ |
for (i = 0; i < 3; i++) |
266 |
+ |
c1[i] = sp1->aim[i] - d*dir[i]; |
267 |
+ |
d = DOT(sp2->aim, dir); |
268 |
+ |
for (i = 0; i < 3; i++) |
269 |
+ |
c2[i] = sp2->aim[i] - d*dir[i]; |
270 |
+ |
/* compute overlap */ |
271 |
+ |
rad2 = intercircle(cent, c1, c2, sp1->siz/PI, sp2->siz/PI); |
272 |
+ |
if (rad2 <= FTINY) |
273 |
+ |
return(0); |
274 |
+ |
VCOPY(sp1->aim, cent); |
275 |
+ |
sp1->siz = PI*rad2; |
276 |
+ |
return(1); |
277 |
+ |
} |
278 |
+ |
|
279 |
+ |
|
280 |
+ |
checkspot(sp, nrm) /* check spotlight for behind source */ |
281 |
+ |
register SPOT *sp; /* spotlight */ |
282 |
+ |
FVECT nrm; /* source surface normal */ |
283 |
+ |
{ |
284 |
+ |
double d, d1; |
285 |
+ |
|
286 |
+ |
d = DOT(sp->aim, nrm); |
287 |
+ |
if (d > FTINY) /* center in front? */ |
288 |
+ |
return(0); |
289 |
+ |
/* else check horizon */ |
290 |
+ |
d1 = 1. - sp->siz/(2.*PI); |
291 |
+ |
return(1.-FTINY-d*d > d1*d1); |
292 |
+ |
} |
293 |
+ |
|
294 |
+ |
|
295 |
+ |
double |
296 |
+ |
intercircle(cc, c1, c2, r1s, r2s) /* intersect two circles */ |
297 |
+ |
FVECT cc; /* midpoint (return value) */ |
298 |
+ |
FVECT c1, c2; /* circle centers */ |
299 |
+ |
double r1s, r2s; /* radii squared */ |
300 |
+ |
{ |
301 |
+ |
double a2, d2, l; |
302 |
+ |
FVECT disp; |
303 |
+ |
register int i; |
304 |
+ |
|
305 |
+ |
for (i = 0; i < 3; i++) |
306 |
+ |
disp[i] = c2[i] - c1[i]; |
307 |
+ |
d2 = DOT(disp,disp); |
308 |
+ |
/* circle within overlap? */ |
309 |
+ |
if (r1s < r2s) { |
310 |
+ |
if (r2s >= r1s + d2) { |
311 |
+ |
VCOPY(cc, c1); |
312 |
+ |
return(r1s); |
313 |
+ |
} |
314 |
+ |
} else { |
315 |
+ |
if (r1s >= r2s + d2) { |
316 |
+ |
VCOPY(cc, c2); |
317 |
+ |
return(r2s); |
318 |
+ |
} |
319 |
+ |
} |
320 |
+ |
a2 = .25*(2.*(r1s+r2s) - d2 - (r2s-r1s)*(r2s-r1s)/d2); |
321 |
+ |
/* no overlap? */ |
322 |
+ |
if (a2 <= 0.) |
323 |
+ |
return(0.); |
324 |
+ |
/* overlap, compute center */ |
325 |
+ |
l = sqrt((r1s - a2)/d2); |
326 |
+ |
for (i = 0; i < 3; i++) |
327 |
+ |
cc[i] = c1[i] + l*disp[i]; |
328 |
+ |
return(a2); |
329 |
|
} |
330 |
|
|
331 |
|
|