| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 // G4TriangularFacet implementation
27 //
28 // 31.10.2004, P R Truscott, QinetiQ Ltd, UK - Created.
29 // 01.08.2007, P R Truscott, QinetiQ Ltd, UK
30 // Significant modification to correct for errors and enhance
31 // based on patches/observations kindly provided by Rickard
32 // Holmberg.
33 // 12.10.2012, M Gayer, CERN
34 // New implementation reducing memory requirements by 50%,
35 // and considerable CPU speedup together with the new
36 // implementation of G4TessellatedSolid.
37 // 23.02.2016, E Tcherniaev, CERN
38 // Improved test to detect degenerate (too small or
39 // too narrow) triangles.
40 // --------------------------------------------------------------------
41
42 #include "G4TriangularFacet.hh"
43
44 #include "Randomize.hh"
45 #include "G4TessellatedGeometryAlgorithms.hh"
46
47 using namespace std;
48
49 ///////////////////////////////////////////////////////////////////////////////
50 //
51 // Definition of triangular facet using absolute vectors to fVertices.
52 // From this for first vector is retained to define the facet location and
53 // two relative vectors (E0 and E1) define the sides and orientation of
54 // the outward surface normal.
55 //
56 G4TriangularFacet::G4TriangularFacet (const G4ThreeVector& vt0,
57 const G4ThreeVector& vt1,
58 const G4ThreeVector& vt2,
59 G4FacetVertexType vertexType)
60 {
61 fVertices = new vector<G4ThreeVector>(3);
62
63 SetVertex(0, vt0);
64 if (vertexType == ABSOLUTE)
65 {
66 SetVertex(1, vt1);
67 SetVertex(2, vt2);
68 fE1 = vt1 - vt0;
69 fE2 = vt2 - vt0;
70 }
71 else
72 {
73 SetVertex(1, vt0 + vt1);
74 SetVertex(2, vt0 + vt2);
75 fE1 = vt1;
76 fE2 = vt2;
77 }
78
79 G4ThreeVector E1xE2 = fE1.cross(fE2);
80 fArea = 0.5 * E1xE2.mag();
81 for (G4int i = 0; i < 3; ++i) fIndices[i] = -1;
82
83 fIsDefined = true;
84 G4double delta = kCarTolerance; // Set tolerance for checking
85
86 // Check length of edges
87 //
88 G4double leng1 = fE1.mag();
89 G4double leng2 = (fE2-fE1).mag();
90 G4double leng3 = fE2.mag();
91 if (leng1 <= delta || leng2 <= delta || leng3 <= delta)
92 {
93 fIsDefined = false;
94 }
95
96 // Check min height of triangle
97 //
98 if (fIsDefined)
99 {
100 if (2.*fArea/std::max(std::max(leng1,leng2),leng3) <= delta)
101 {
102 fIsDefined = false;
103 }
104 }
105
106 // Define facet
107 //
108 if (!fIsDefined)
109 {
110 ostringstream message;
111 message << "Facet is too small or too narrow." << G4endl
112 << "Triangle area = " << fArea << G4endl
113 << "P0 = " << GetVertex(0) << G4endl
114 << "P1 = " << GetVertex(1) << G4endl
115 << "P2 = " << GetVertex(2) << G4endl
116 << "Side1 length (P0->P1) = " << leng1 << G4endl
117 << "Side2 length (P1->P2) = " << leng2 << G4endl
118 << "Side3 length (P2->P0) = " << leng3;
119 G4Exception("G4TriangularFacet::G4TriangularFacet()",
120 "GeomSolids1001", JustWarning, message);
121 fSurfaceNormal.set(0,0,0);
122 fA = fB = fC = 0.0;
123 fDet = 0.0;
124 fCircumcentre = vt0 + 0.5*fE1 + 0.5*fE2;
125 fArea = fRadius = 0.0;
126 }
127 else
128 {
129 fSurfaceNormal = E1xE2.unit();
130 fA = fE1.mag2();
131 fB = fE1.dot(fE2);
132 fC = fE2.mag2();
133 fDet = std::fabs(fA*fC - fB*fB);
134
135 fCircumcentre =
136 vt0 + (E1xE2.cross(fE1)*fC + fE2.cross(E1xE2)*fA) / (2.*E1xE2.mag2());
137 fRadius = (fCircumcentre - vt0).mag();
138 }
139 }
140
141 ///////////////////////////////////////////////////////////////////////////////
142 //
143 G4TriangularFacet::G4TriangularFacet ()
144 {
145 fVertices = new vector<G4ThreeVector>(3);
146 G4ThreeVector zero(0,0,0);
147 SetVertex(0, zero);
148 SetVertex(1, zero);
149 SetVertex(2, zero);
150 for (G4int i = 0; i < 3; ++i) fIndices[i] = -1;
151 fIsDefined = false;
152 fSurfaceNormal.set(0,0,0);
153 fA = fB = fC = 0;
154 fE1 = zero;
155 fE2 = zero;
156 fDet = 0.0;
157 fArea = fRadius = 0.0;
158 }
159
160 ///////////////////////////////////////////////////////////////////////////////
161 //
162 G4TriangularFacet::~G4TriangularFacet ()
163 {
164 SetVertices(nullptr);
165 }
166
167 ///////////////////////////////////////////////////////////////////////////////
168 //
169 void G4TriangularFacet::CopyFrom (const G4TriangularFacet& rhs)
170 {
171 auto p = (char *) &rhs;
172 copy(p, p + sizeof(*this), (char *)this);
173
174 if (fIndices[0] < 0 && fVertices == nullptr)
175 {
176 fVertices = new vector<G4ThreeVector>(3);
177 for (G4int i = 0; i < 3; ++i) (*fVertices)[i] = (*rhs.fVertices)[i];
178 }
179 }
180
181 ///////////////////////////////////////////////////////////////////////////////
182 //
183 void G4TriangularFacet::MoveFrom (G4TriangularFacet& rhs)
184 {
185 fSurfaceNormal = std::move(rhs.fSurfaceNormal);
186 fArea = rhs.fArea;
187 fCircumcentre = std::move(rhs.fCircumcentre);
188 fRadius = rhs.fRadius;
189 fIndices = rhs.fIndices;
190 fA = rhs.fA; fB = rhs.fB; fC = rhs.fC;
191 fDet = rhs.fDet;
192 fSqrDist = rhs.fSqrDist;
193 fE1 = std::move(rhs.fE1); fE2 = std::move(rhs.fE2);
194 fIsDefined = rhs.fIsDefined;
195 fVertices = rhs.fVertices;
196 rhs.fVertices = nullptr;
197 }
198
199 ///////////////////////////////////////////////////////////////////////////////
200 //
201 G4TriangularFacet::G4TriangularFacet (const G4TriangularFacet& rhs)
202 : G4VFacet(rhs)
203 {
204 CopyFrom(rhs);
205 }
206
207 ///////////////////////////////////////////////////////////////////////////////
208 //
209 G4TriangularFacet::G4TriangularFacet (G4TriangularFacet&& rhs) noexcept
210 : G4VFacet(rhs)
211 {
212 MoveFrom(rhs);
213 }
214
215 ///////////////////////////////////////////////////////////////////////////////
216 //
217 G4TriangularFacet&
218 G4TriangularFacet::operator=(const G4TriangularFacet& rhs)
219 {
220 SetVertices(nullptr);
221
222 if (this != &rhs)
223 {
224 delete fVertices;
225 CopyFrom(rhs);
226 }
227
228 return *this;
229 }
230
231 ///////////////////////////////////////////////////////////////////////////////
232 //
233 G4TriangularFacet&
234 G4TriangularFacet::operator=(G4TriangularFacet&& rhs) noexcept
235 {
236 SetVertices(nullptr);
237
238 if (this != &rhs)
239 {
240 delete fVertices;
241 MoveFrom(rhs);
242 }
243
244 return *this;
245 }
246
247 ///////////////////////////////////////////////////////////////////////////////
248 //
249 // GetClone
250 //
251 // Simple member function to generate fA duplicate of the triangular facet.
252 //
253 G4VFacet* G4TriangularFacet::GetClone ()
254 {
255 auto fc = new G4TriangularFacet (GetVertex(0), GetVertex(1),
256 GetVertex(2), ABSOLUTE);
257 return fc;
258 }
259
260 ///////////////////////////////////////////////////////////////////////////////
261 //
262 // GetFlippedFacet
263 //
264 // Member function to generate an identical facet, but with the normal vector
265 // pointing at 180 degrees.
266 //
267 G4TriangularFacet* G4TriangularFacet::GetFlippedFacet ()
268 {
269 auto flipped = new G4TriangularFacet (GetVertex(0), GetVertex(1),
270 GetVertex(2), ABSOLUTE);
271 return flipped;
272 }
273
274 ///////////////////////////////////////////////////////////////////////////////
275 //
276 // Distance (G4ThreeVector)
277 //
278 // Determines the vector between p and the closest point on the facet to p.
279 // This is based on the algorithm published in "Geometric Tools for Computer
280 // Graphics," Philip J Scheider and David H Eberly, Elsevier Science (USA),
281 // 2003. at the time of writing, the algorithm is also available in fA
282 // technical note "Distance between point and triangle in 3D," by David Eberly
283 // at http://www.geometrictools.com/Documentation/DistancePoint3Triangle3.pdf
284 //
285 // The by-product is the square-distance fSqrDist, which is retained
286 // in case needed by the other "Distance" member functions.
287 //
288 G4ThreeVector G4TriangularFacet::Distance (const G4ThreeVector& p)
289 {
290 G4ThreeVector D = GetVertex(0) - p;
291 G4double d = fE1.dot(D);
292 G4double e = fE2.dot(D);
293 G4double f = D.mag2();
294 G4double q = fB*e - fC*d;
295 G4double t = fB*d - fA*e;
296 fSqrDist = 0.;
297
298 if (q+t <= fDet)
299 {
300 if (q < 0.0)
301 {
302 if (t < 0.0)
303 {
304 //
305 // We are in region 4.
306 //
307 if (d < 0.0)
308 {
309 t = 0.0;
310 if (-d >= fA) {q = 1.0; fSqrDist = fA + 2.0*d + f;}
311 else {q = -d/fA; fSqrDist = d*q + f;}
312 }
313 else
314 {
315 q = 0.0;
316 if (e >= 0.0) {t = 0.0; fSqrDist = f;}
317 else if (-e >= fC) {t = 1.0; fSqrDist = fC + 2.0*e + f;}
318 else {t = -e/fC; fSqrDist = e*t + f;}
319 }
320 }
321 else
322 {
323 //
324 // We are in region 3.
325 //
326 q = 0.0;
327 if (e >= 0.0) {t = 0.0; fSqrDist = f;}
328 else if (-e >= fC) {t = 1.0; fSqrDist = fC + 2.0*e + f;}
329 else {t = -e/fC; fSqrDist = e*t + f;}
330 }
331 }
332 else if (t < 0.0)
333 {
334 //
335 // We are in region 5.
336 //
337 t = 0.0;
338 if (d >= 0.0) {q = 0.0; fSqrDist = f;}
339 else if (-d >= fA) {q = 1.0; fSqrDist = fA + 2.0*d + f;}
340 else {q = -d/fA; fSqrDist = d*q + f;}
341 }
342 else
343 {
344 //
345 // We are in region 0.
346 //
347 G4double dist = fSurfaceNormal.dot(D);
348 fSqrDist = dist*dist;
349 return fSurfaceNormal*dist;
350 }
351 }
352 else
353 {
354 if (q < 0.0)
355 {
356 //
357 // We are in region 2.
358 //
359 G4double tmp0 = fB + d;
360 G4double tmp1 = fC + e;
361 if (tmp1 > tmp0)
362 {
363 G4double numer = tmp1 - tmp0;
364 G4double denom = fA - 2.0*fB + fC;
365 if (numer >= denom) {q = 1.0; t = 0.0; fSqrDist = fA + 2.0*d + f;}
366 else
367 {
368 q = numer/denom;
369 t = 1.0 - q;
370 fSqrDist = q*(fA*q + fB*t +2.0*d) + t*(fB*q + fC*t + 2.0*e) + f;
371 }
372 }
373 else
374 {
375 q = 0.0;
376 if (tmp1 <= 0.0) {t = 1.0; fSqrDist = fC + 2.0*e + f;}
377 else if (e >= 0.0) {t = 0.0; fSqrDist = f;}
378 else {t = -e/fC; fSqrDist = e*t + f;}
379 }
380 }
381 else if (t < 0.0)
382 {
383 //
384 // We are in region 6.
385 //
386 G4double tmp0 = fB + e;
387 G4double tmp1 = fA + d;
388 if (tmp1 > tmp0)
389 {
390 G4double numer = tmp1 - tmp0;
391 G4double denom = fA - 2.0*fB + fC;
392 if (numer >= denom) {t = 1.0; q = 0.0; fSqrDist = fC + 2.0*e + f;}
393 else
394 {
395 t = numer/denom;
396 q = 1.0 - t;
397 fSqrDist = q*(fA*q + fB*t +2.0*d) + t*(fB*q + fC*t + 2.0*e) + f;
398 }
399 }
400 else
401 {
402 t = 0.0;
403 if (tmp1 <= 0.0) {q = 1.0; fSqrDist = fA + 2.0*d + f;}
404 else if (d >= 0.0) {q = 0.0; fSqrDist = f;}
405 else {q = -d/fA; fSqrDist = d*q + f;}
406 }
407 }
408 else
409 //
410 // We are in region 1.
411 //
412 {
413 G4double numer = fC + e - fB - d;
414 if (numer <= 0.0)
415 {
416 q = 0.0;
417 t = 1.0;
418 fSqrDist = fC + 2.0*e + f;
419 }
420 else
421 {
422 G4double denom = fA - 2.0*fB + fC;
423 if (numer >= denom) {q = 1.0; t = 0.0; fSqrDist = fA + 2.0*d + f;}
424 else
425 {
426 q = numer/denom;
427 t = 1.0 - q;
428 fSqrDist = q*(fA*q + fB*t + 2.0*d) + t*(fB*q + fC*t + 2.0*e) + f;
429 }
430 }
431 }
432 }
433 //
434 //
435 // Do fA check for rounding errors in the distance-squared. It appears that
436 // the conventional methods for calculating fSqrDist breaks down when very
437 // near to or at the surface (as required by transport).
438 // We'll therefore also use the magnitude-squared of the vector displacement.
439 // (Note that I've also tried to get around this problem by using the
440 // existing equations for
441 //
442 // fSqrDist = function(fA,fB,fC,d,q,t)
443 //
444 // and use fA more accurate addition process which minimises errors and
445 // breakdown of cummutitivity [where (A+B)+C != A+(B+C)] but this still
446 // doesn't work.
447 // Calculation from u = D + q*fE1 + t*fE2 is less efficient, but appears
448 // more robust.
449 //
450 if (fSqrDist < 0.0) fSqrDist = 0.;
451 G4ThreeVector u = D + q*fE1 + t*fE2;
452 G4double u2 = u.mag2();
453 //
454 // The following (part of the roundoff error check) is from Oliver Merle'q
455 // updates.
456 //
457 if (fSqrDist > u2) fSqrDist = u2;
458
459 return u;
460 }
461
462 ///////////////////////////////////////////////////////////////////////////////
463 //
464 // Distance (G4ThreeVector, G4double)
465 //
466 // Determines the closest distance between point p and the facet. This makes
467 // use of G4ThreeVector G4TriangularFacet::Distance, which stores the
468 // square of the distance in variable fSqrDist. If approximate methods show
469 // the distance is to be greater than minDist, then forget about further
470 // computation and return fA very large number.
471 //
472 G4double G4TriangularFacet::Distance (const G4ThreeVector& p,
473 G4double minDist)
474 {
475 //
476 // Start with quicky test to determine if the surface of the sphere enclosing
477 // the triangle is any closer to p than minDist. If not, then don't bother
478 // about more accurate test.
479 //
480 G4double dist = kInfinity;
481 if ((p-fCircumcentre).mag()-fRadius < minDist)
482 {
483 //
484 // It's possible that the triangle is closer than minDist,
485 // so do more accurate assessment.
486 //
487 dist = Distance(p).mag();
488 }
489 return dist;
490 }
491
492 ///////////////////////////////////////////////////////////////////////////////
493 //
494 // Distance (G4ThreeVector, G4double, G4bool)
495 //
496 // Determine the distance to point p. kInfinity is returned if either:
497 // (1) outgoing is TRUE and the dot product of the normal vector to the facet
498 // and the displacement vector from p to the triangle is negative.
499 // (2) outgoing is FALSE and the dot product of the normal vector to the facet
500 // and the displacement vector from p to the triangle is positive.
501 // If approximate methods show the distance is to be greater than minDist, then
502 // forget about further computation and return fA very large number.
503 //
504 // This method has been heavily modified thanks to the valuable comments and
505 // corrections of Rickard Holmberg.
506 //
507 G4double G4TriangularFacet::Distance (const G4ThreeVector& p,
508 G4double minDist,
509 const G4bool outgoing)
510 {
511 //
512 // Start with quicky test to determine if the surface of the sphere enclosing
513 // the triangle is any closer to p than minDist. If not, then don't bother
514 // about more accurate test.
515 //
516 G4double dist = kInfinity;
517 if ((p-fCircumcentre).mag()-fRadius < minDist)
518 {
519 //
520 // It's possible that the triangle is closer than minDist,
521 // so do more accurate assessment.
522 //
523 G4ThreeVector v = Distance(p);
524 G4double dist1 = sqrt(fSqrDist);
525 G4double dir = v.dot(fSurfaceNormal);
526 G4bool wrongSide = (dir > 0.0 && !outgoing) || (dir < 0.0 && outgoing);
527 if (dist1 <= kCarTolerance)
528 {
529 //
530 // Point p is very close to triangle. Check if it's on the wrong side,
531 // in which case return distance of 0.0 otherwise .
532 //
533 if (wrongSide) dist = 0.0;
534 else dist = dist1;
535 }
536 else if (!wrongSide) dist = dist1;
537 }
538 return dist;
539 }
540
541 ///////////////////////////////////////////////////////////////////////////////
542 //
543 // Extent
544 //
545 // Calculates the furthest the triangle extends in fA particular direction
546 // defined by the vector axis.
547 //
548 G4double G4TriangularFacet::Extent (const G4ThreeVector axis)
549 {
550 G4double ss = GetVertex(0).dot(axis);
551 G4double sp = GetVertex(1).dot(axis);
552 if (sp > ss) ss = sp;
553 sp = GetVertex(2).dot(axis);
554 if (sp > ss) ss = sp;
555 return ss;
556 }
557
558 ///////////////////////////////////////////////////////////////////////////////
559 //
560 // Intersect
561 //
562 // Member function to find the next intersection when going from p in the
563 // direction of v. If:
564 // (1) "outgoing" is TRUE, only consider the face if we are going out through
565 // the face.
566 // (2) "outgoing" is FALSE, only consider the face if we are going in through
567 // the face.
568 // Member functions returns TRUE if there is an intersection, FALSE otherwise.
569 // Sets the distance (distance along w), distFromSurface (orthogonal distance)
570 // and normal.
571 //
572 // Also considers intersections that happen with negative distance for small
573 // distances of distFromSurface = 0.5*kCarTolerance in the wrong direction.
574 // This is to detect kSurface without doing fA full Inside(p) in
575 // G4TessellatedSolid::Distance(p,v) calculation.
576 //
577 // This member function is thanks the valuable work of Rickard Holmberg. PT.
578 // However, "gotos" are the Work of the Devil have been exorcised with
579 // extreme prejudice!!
580 //
581 // IMPORTANT NOTE: These calculations are predicated on v being fA unit
582 // vector. If G4TessellatedSolid or other classes call this member function
583 // with |v| != 1 then there will be errors.
584 //
585 G4bool G4TriangularFacet::Intersect (const G4ThreeVector& p,
586 const G4ThreeVector& v,
587 G4bool outgoing,
588 G4double& distance,
589 G4double& distFromSurface,
590 G4ThreeVector& normal)
591 {
592 //
593 // Check whether the direction of the facet is consistent with the vector v
594 // and the need to be outgoing or ingoing. If inconsistent, disregard and
595 // return false.
596 //
597 G4double w = v.dot(fSurfaceNormal);
598 if ((outgoing && w < -dirTolerance) || (!outgoing && w > dirTolerance))
599 {
600 distance = kInfinity;
601 distFromSurface = kInfinity;
602 normal.set(0,0,0);
603 return false;
604 }
605 //
606 // Calculate the orthogonal distance from p to the surface containing the
607 // triangle. Then determine if we're on the right or wrong side of the
608 // surface (at fA distance greater than kCarTolerance to be consistent with
609 // "outgoing".
610 //
611 const G4ThreeVector& p0 = GetVertex(0);
612 G4ThreeVector D = p0 - p;
613 distFromSurface = D.dot(fSurfaceNormal);
614 G4bool wrongSide = (outgoing && distFromSurface < -0.5*kCarTolerance) ||
615 (!outgoing && distFromSurface > 0.5*kCarTolerance);
616
617 if (wrongSide)
618 {
619 distance = kInfinity;
620 distFromSurface = kInfinity;
621 normal.set(0,0,0);
622 return false;
623 }
624
625 wrongSide = (outgoing && distFromSurface < 0.0)
626 || (!outgoing && distFromSurface > 0.0);
627 if (wrongSide)
628 {
629 //
630 // We're slightly on the wrong side of the surface. Check if we're close
631 // enough using fA precise distance calculation.
632 //
633 G4ThreeVector u = Distance(p);
634 if (fSqrDist <= kCarTolerance*kCarTolerance)
635 {
636 //
637 // We're very close. Therefore return fA small negative number
638 // to pretend we intersect.
639 //
640 // distance = -0.5*kCarTolerance
641 distance = 0.0;
642 normal = fSurfaceNormal;
643 return true;
644 }
645 else
646 {
647 //
648 // We're close to the surface containing the triangle, but sufficiently
649 // far from the triangle, and on the wrong side compared to the directions
650 // of the surface normal and v. There is no intersection.
651 //
652 distance = kInfinity;
653 distFromSurface = kInfinity;
654 normal.set(0,0,0);
655 return false;
656 }
657 }
658 if (w < dirTolerance && w > -dirTolerance)
659 {
660 //
661 // The ray is within the plane of the triangle. Project the problem into 2D
662 // in the plane of the triangle. First try to create orthogonal unit vectors
663 // mu and nu, where mu is fE1/|fE1|. This is kinda like
664 // the original algorithm due to Rickard Holmberg, but with better
665 // mathematical justification than the original method ... however,
666 // beware Rickard's was less time-consuming.
667 //
668 // Note that vprime is not fA unit vector. We need to keep it unnormalised
669 // since the values of distance along vprime (s0 and s1) for intersection
670 // with the triangle will be used to determine if we cut the plane at the
671 // same time.
672 //
673 G4ThreeVector mu = fE1.unit();
674 G4ThreeVector nu = fSurfaceNormal.cross(mu);
675 G4TwoVector pprime(p.dot(mu), p.dot(nu));
676 G4TwoVector vprime(v.dot(mu), v.dot(nu));
677 G4TwoVector P0prime(p0.dot(mu), p0.dot(nu));
678 G4TwoVector E0prime(fE1.mag(), 0.0);
679 G4TwoVector E1prime(fE2.dot(mu), fE2.dot(nu));
680 G4TwoVector loc[2];
681 if (G4TessellatedGeometryAlgorithms::IntersectLineAndTriangle2D(pprime,
682 vprime, P0prime, E0prime, E1prime, loc))
683 {
684 //
685 // There is an intersection between the line and triangle in 2D.
686 // Now check which part of the line intersects with the plane
687 // containing the triangle in 3D.
688 //
689 G4double vprimemag = vprime.mag();
690 G4double s0 = (loc[0] - pprime).mag()/vprimemag;
691 G4double s1 = (loc[1] - pprime).mag()/vprimemag;
692 G4double normDist0 = fSurfaceNormal.dot(s0*v) - distFromSurface;
693 G4double normDist1 = fSurfaceNormal.dot(s1*v) - distFromSurface;
694
695 if ((normDist0 < 0.0 && normDist1 < 0.0)
696 || (normDist0 > 0.0 && normDist1 > 0.0)
697 || (normDist0 == 0.0 && normDist1 == 0.0) )
698 {
699 distance = kInfinity;
700 distFromSurface = kInfinity;
701 normal.set(0,0,0);
702 return false;
703 }
704 else
705 {
706 G4double dnormDist = normDist1 - normDist0;
707 if (fabs(dnormDist) < DBL_EPSILON)
708 {
709 distance = s0;
710 normal = fSurfaceNormal;
711 if (!outgoing) distFromSurface = -distFromSurface;
712 return true;
713 }
714 else
715 {
716 distance = s0 - normDist0*(s1-s0)/dnormDist;
717 normal = fSurfaceNormal;
718 if (!outgoing) distFromSurface = -distFromSurface;
719 return true;
720 }
721 }
722 }
723 else
724 {
725 distance = kInfinity;
726 distFromSurface = kInfinity;
727 normal.set(0,0,0);
728 return false;
729 }
730 }
731 //
732 //
733 // Use conventional algorithm to determine the whether there is an
734 // intersection. This involves determining the point of intersection of the
735 // line with the plane containing the triangle, and then calculating if the
736 // point is within the triangle.
737 //
738 distance = distFromSurface / w;
739 G4ThreeVector pp = p + v*distance;
740 G4ThreeVector DD = p0 - pp;
741 G4double d = fE1.dot(DD);
742 G4double e = fE2.dot(DD);
743 G4double ss = fB*e - fC*d;
744 G4double t = fB*d - fA*e;
745
746 G4double sTolerance = (fabs(fB)+ fabs(fC) + fabs(d) + fabs(e))*kCarTolerance;
747 G4double tTolerance = (fabs(fA)+ fabs(fB) + fabs(d) + fabs(e))*kCarTolerance;
748 G4double detTolerance = (fabs(fA)+ fabs(fC) + 2*fabs(fB) )*kCarTolerance;
749
750 //if (ss < 0.0 || t < 0.0 || ss+t > fDet)
751 if (ss < -sTolerance || t < -tTolerance || ( ss+t - fDet ) > detTolerance)
752 {
753 //
754 // The intersection is outside of the triangle.
755 //
756 distance = distFromSurface = kInfinity;
757 normal.set(0,0,0);
758 return false;
759 }
760 else
761 {
762 //
763 // There is an intersection. Now we only need to set the surface normal.
764 //
765 normal = fSurfaceNormal;
766 if (!outgoing) distFromSurface = -distFromSurface;
767 return true;
768 }
769 }
770
771 ////////////////////////////////////////////////////////////////////////
772 //
773 // GetPointOnFace
774 //
775 // Auxiliary method, returns a uniform random point on the facet
776 //
777 G4ThreeVector G4TriangularFacet::GetPointOnFace() const
778 {
779 G4double u = G4UniformRand();
780 G4double v = G4UniformRand();
781 if (u+v > 1.) { u = 1. - u; v = 1. - v; }
782 return GetVertex(0) + u*fE1 + v*fE2;
783 }
784
785 ////////////////////////////////////////////////////////////////////////
786 //
787 // GetArea
788 //
789 // Auxiliary method for returning the surface fArea
790 //
791 G4double G4TriangularFacet::GetArea() const
792 {
793 return fArea;
794 }
795
796 ////////////////////////////////////////////////////////////////////////
797 //
798 G4GeometryType G4TriangularFacet::GetEntityType () const
799 {
800 return "G4TriangularFacet";
801 }
802
803 ////////////////////////////////////////////////////////////////////////
804 //
805 G4ThreeVector G4TriangularFacet::GetSurfaceNormal () const
806 {
807 return fSurfaceNormal;
808 }
809
810 ////////////////////////////////////////////////////////////////////////
811 //
812 void G4TriangularFacet::SetSurfaceNormal (const G4ThreeVector& normal)
813 {
814 fSurfaceNormal = normal;
815 }
816