summaryrefslogtreecommitdiff
path: root/core/math/geometry.h
blob: 826e4697b5fc3687ef89ae934b73144a801f8037 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
/*************************************************************************/
/*  geometry.h                                                           */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/
#ifndef GEOMETRY_H
#define GEOMETRY_H

#include "vector3.h"
#include "face3.h"
#include "dvector.h"
#include "math_2d.h"
#include "vector.h"
#include "print_string.h"
#include "object.h"
#include "triangulate.h"
/**
	@author Juan Linietsky <reduzio@gmail.com>
*/

class Geometry {
	Geometry();
public:
	



	static float get_closest_points_between_segments( const Vector2& p1,const Vector2& q1, const Vector2& p2,const Vector2& q2, Vector2& c1, Vector2& c2) {

		Vector2 d1 = q1 - p1; // Direction vector of segment S1
		Vector2 d2 = q2 - p2; // Direction vector of segment S2
		Vector2 r = p1 - p2;
		float a = d1.dot(d1); // Squared length of segment S1, always nonnegative
		float e = d2.dot(d2); // Squared length of segment S2, always nonnegative
		float f = d2.dot(r);
		float s,t;
		// Check if either or both segments degenerate into points
		if (a <= CMP_EPSILON && e <= CMP_EPSILON) {
			// Both segments degenerate into points
			c1 = p1;
			c2 = p2;
			return Math::sqrt((c1 - c2).dot(c1 - c2));
		}
		if (a <= CMP_EPSILON) {
			// First segment degenerates into a point
			s = 0.0f;
			t = f / e; // s = 0 => t = (b*s + f) / e = f / e
			t = CLAMP(t, 0.0f, 1.0f);
		} else {
			float c = d1.dot(r);
			if (e <= CMP_EPSILON) {
				// Second segment degenerates into a point
				t = 0.0f;
				s = CLAMP(-c / a, 0.0f, 1.0f); // t = 0 => s = (b*t - c) / a = -c / a
			} else {
				// The general nondegenerate case starts here
				float b = d1.dot(d2);
				float denom = a*e-b*b; // Always nonnegative
				// If segments not parallel, compute closest point on L1 to L2 and
				// clamp to segment S1. Else pick arbitrary s (here 0)
				if (denom != 0.0f) {
					s = CLAMP((b*f - c*e) / denom, 0.0f, 1.0f);
				} else
					s = 0.0f;
				// Compute point on L2 closest to S1(s) using
				// t = Dot((P1 + D1*s) - P2,D2) / Dot(D2,D2) = (b*s + f) / e
				t = (b*s + f) / e;

				//If t in [0,1] done. Else clamp t, recompute s for the new value
				// of t using s = Dot((P2 + D2*t) - P1,D1) / Dot(D1,D1)= (t*b - c) / a
				// and clamp s to [0, 1]
				if (t < 0.0f) {
					t = 0.0f;
					s = CLAMP(-c / a, 0.0f, 1.0f);
				} else if (t > 1.0f) {
					t = 1.0f;
					s = CLAMP((b - c) / a, 0.0f, 1.0f);
				}
			}
		}
		c1 = p1 + d1 * s;
		c2 = p2 + d2 * t;
		return Math::sqrt((c1 - c2).dot(c1 - c2));
	}


	static void get_closest_points_between_segments(const Vector3& p1,const Vector3& p2,const Vector3& q1,const Vector3& q2,Vector3& c1, Vector3& c2)
	{
		//do the function 'd' as defined by pb. I think is is dot product of some sort
#define d_of(m,n,o,p) ( (m.x - n.x) * (o.x - p.x) + (m.y - n.y) * (o.y - p.y) + (m.z - n.z) * (o.z - p.z) )

		//caluclate the parpametric position on the 2 curves, mua and mub
		float mua = ( d_of(p1,q1,q2,q1) * d_of(q2,q1,p2,p1)  - d_of(p1,q1,p2,p1) * d_of(q2,q1,q2,q1) ) / ( d_of(p2,p1,p2,p1) * d_of(q2,q1,q2,q1)  - d_of(q2,q1,p2,p1) * d_of(q2,q1,p2,p1) );
		float mub = ( d_of(p1,q1,q2,q1) + mua * d_of(q2,q1,p2,p1)  ) / d_of(q2,q1,q2,q1);

		//clip the value between [0..1] constraining the solution to lie on the original curves
		if (mua < 0) mua = 0;
		if (mub < 0) mub = 0;
		if (mua > 1) mua = 1;
		if (mub > 1) mub = 1;
		c1 = p1.linear_interpolate(p2,mua);
		c2 = q1.linear_interpolate(q2,mub);
	}

	static float get_closest_distance_between_segments( const Vector3& p_from_a,const Vector3& p_to_a, const Vector3& p_from_b,const Vector3& p_to_b) {
	    Vector3   u = p_to_a - p_from_a;
	    Vector3   v = p_to_b - p_from_b;
	    Vector3   w = p_from_a - p_to_a;
	    real_t    a = u.dot(u);        // always >= 0
	    real_t    b = u.dot(v);
	    real_t    c = v.dot(v);        // always >= 0
	    real_t    d = u.dot(w);
	    real_t    e = v.dot(w);
	    real_t    D = a*c - b*b;       // always >= 0
	    real_t    sc, sN, sD = D;      // sc = sN / sD, default sD = D >= 0
	    real_t    tc, tN, tD = D;      // tc = tN / tD, default tD = D >= 0

	    // compute the line parameters of the two closest points
	    if (D < CMP_EPSILON) { // the lines are almost parallel
		sN = 0.0;        // force using point P0 on segment S1
		sD = 1.0;        // to prevent possible division by 0.0 later
		tN = e;
		tD = c;
	    }
	    else {                // get the closest points on the infinite lines
		sN = (b*e - c*d);
		tN = (a*e - b*d);
		if (sN < 0.0) {       // sc < 0 => the s=0 edge is visible
		    sN = 0.0;
		    tN = e;
		    tD = c;
		}
		else if (sN > sD) {  // sc > 1 => the s=1 edge is visible
		    sN = sD;
		    tN = e + b;
		    tD = c;
		}
	    }

	    if (tN < 0.0) {           // tc < 0 => the t=0 edge is visible
		tN = 0.0;
		// recompute sc for this edge
		if (-d < 0.0)
		    sN = 0.0;
		else if (-d > a)
		    sN = sD;
		else {
		    sN = -d;
		    sD = a;
		}
	    }
	    else if (tN > tD) {      // tc > 1 => the t=1 edge is visible
		tN = tD;
		// recompute sc for this edge
		if ((-d + b) < 0.0)
		    sN = 0;
		else if ((-d + b) > a)
		    sN = sD;
		else {
		    sN = (-d + b);
		    sD = a;
		}
	    }
	    // finally do the division to get sc and tc
	    sc = (Math::abs(sN) < CMP_EPSILON ? 0.0 : sN / sD);
	    tc = (Math::abs(tN) < CMP_EPSILON ? 0.0 : tN / tD);

	    // get the difference of the two closest points
	    Vector3   dP = w + (sc * u) - (tc * v);  // = S1(sc) - S2(tc)

	    return dP.length();   // return the closest distance
	}

	static inline bool ray_intersects_triangle( const Vector3& p_from, const Vector3& p_dir, const Vector3& p_v0,const Vector3& p_v1,const Vector3& p_v2,Vector3* r_res=0) {
		Vector3 e1=p_v1-p_v0;
		Vector3 e2=p_v2-p_v0;
		Vector3 h = p_dir.cross(e2);
		real_t a =e1.dot(h);
		if (a>-CMP_EPSILON && a < CMP_EPSILON) // parallel test
			return false;
				
		real_t f=1.0/a;
		
		Vector3 s=p_from-p_v0;
		real_t u = f * s.dot(h);
		
		if ( u< 0.0 || u > 1.0)
			return false;
		
		Vector3 q=s.cross(e1);
		
		real_t v = f * p_dir.dot(q);
		
		if (v < 0.0 || u + v > 1.0)
			return false;
		
		// at this stage we can compute t to find out where 
		// the intersection point is on the line
		real_t t = f * e2.dot(q);
		
		if (t > 0.00001) {// ray intersection
			if (r_res)
				*r_res=p_from+p_dir*t;
			return true;
		} else // this means that there is a line intersection  
			// but not a ray intersection
			return false;
	}	
	
	static inline bool segment_intersects_triangle( const Vector3& p_from, const Vector3& p_to, const Vector3& p_v0,const Vector3& p_v1,const Vector3& p_v2,Vector3* r_res=0) {
	
		Vector3 rel=p_to-p_from;
		Vector3 e1=p_v1-p_v0;
		Vector3 e2=p_v2-p_v0;
		Vector3 h = rel.cross(e2);
		real_t a =e1.dot(h);
		if (a>-CMP_EPSILON && a < CMP_EPSILON) // parallel test
			return false;
				
		real_t f=1.0/a;
		
		Vector3 s=p_from-p_v0;
		real_t u = f * s.dot(h);
		
		if ( u< 0.0 || u > 1.0)
			return false;
		
		Vector3 q=s.cross(e1);
		
		real_t v = f * rel.dot(q);
		
		if (v < 0.0 || u + v > 1.0)
			return false;
		
		// at this stage we can compute t to find out where 
		// the intersection point is on the line
		real_t t = f * e2.dot(q);
		
		if (t > CMP_EPSILON && t<=1.0) {// ray intersection
			if (r_res)
				*r_res=p_from+rel*t;
			return true;
		} else // this means that there is a line intersection  
			// but not a ray intersection
			return false;
	}	

	static inline bool segment_intersects_sphere( const Vector3& p_from, const Vector3& p_to, const Vector3& p_sphere_pos,real_t p_sphere_radius,Vector3* r_res=0,Vector3 *r_norm=0) {


		Vector3 sphere_pos=p_sphere_pos-p_from;
		Vector3 rel=(p_to-p_from);
		float  rel_l=rel.length();
		if (rel_l<CMP_EPSILON)
			return false; // both points are the same
		Vector3 normal=rel/rel_l;

		float sphere_d=normal.dot(sphere_pos);

		//Vector3 ray_closest=normal*sphere_d;

		float ray_distance=sphere_pos.distance_to(normal*sphere_d);

		if (ray_distance>=p_sphere_radius)
			return false;

		float inters_d2=p_sphere_radius*p_sphere_radius - ray_distance*ray_distance;
		float inters_d=sphere_d;

		if (inters_d2>=CMP_EPSILON)
			inters_d-=Math::sqrt(inters_d2);

		// check in segment
		if (inters_d<0 || inters_d>rel_l)
			return false;

		Vector3 result=p_from+normal*inters_d;;

		if (r_res)
			*r_res=result;
		if (r_norm)
			*r_norm=(result-p_sphere_pos).normalized();

		return true;
	}

	static inline bool segment_intersects_cylinder( const Vector3& p_from, const Vector3& p_to, float p_height,float p_radius,Vector3* r_res=0,Vector3 *r_norm=0) {

		Vector3 rel=(p_to-p_from);
		float  rel_l=rel.length();
		if (rel_l<CMP_EPSILON)
			return false; // both points are the same

		// first check if they are parallel
		Vector3 normal=(rel/rel_l);
		Vector3 crs = normal.cross(Vector3(0,0,1));
		float crs_l=crs.length();

		Vector3 z_dir;

		if(crs_l<CMP_EPSILON) {
			//blahblah parallel
			z_dir=Vector3(1,0,0); //any x/y vector ok
		} else {
			z_dir=crs/crs_l;
		}

		float dist=z_dir.dot(p_from);

		if (dist>=p_radius)
			return false; // too far away

		// convert to 2D
		float w2=p_radius*p_radius-dist*dist;
		if (w2<CMP_EPSILON)
			return false; //avoid numerical error
		Size2 size(Math::sqrt(w2),p_height*0.5);

		Vector3 x_dir=z_dir.cross(Vector3(0,0,1)).normalized();

		Vector2 from2D(x_dir.dot(p_from),p_from.z);
		Vector2 to2D(x_dir.dot(p_to),p_to.z);

		float min=0,max=1;

		int axis=-1;

		for(int i=0;i<2;i++) {

			real_t seg_from=from2D[i];
			real_t seg_to=to2D[i];
			real_t box_begin=-size[i];
			real_t box_end=size[i];
			real_t cmin,cmax;

	
			if (seg_from < seg_to) {
	
				if (seg_from > box_end || seg_to < box_begin)
					return false;
				real_t length=seg_to-seg_from;
				cmin = (seg_from < box_begin)?((box_begin - seg_from)/length):0;
				cmax = (seg_to > box_end)?((box_end - seg_from)/length):1;
	
			} else {
	
				if (seg_to > box_end || seg_from < box_begin)
					return false;
				real_t length=seg_to-seg_from;
				cmin = (seg_from > box_end)?(box_end - seg_from)/length:0;
				cmax = (seg_to < box_begin)?(box_begin - seg_from)/length:1;
			}
	
			if (cmin > min) {
				min = cmin;
				axis=i;
			}
			if (cmax < max)
				max = cmax;
			if (max < min)
				return false;
		}


		// convert to 3D again
		Vector3 result = p_from + (rel*min);
		Vector3 res_normal = result;

		if (axis==0) {
			res_normal.z=0;
		} else {
			res_normal.x=0;
			res_normal.y=0;
		}


		res_normal.normalize();

		if (r_res)
			*r_res=result;
		if (r_norm)
			*r_norm=res_normal;

		return true;
	}


	static bool segment_intersects_convex(const Vector3& p_from, const Vector3& p_to,const Plane* p_planes, int p_plane_count,Vector3 *p_res, Vector3 *p_norm) {

		real_t min=-1e20,max=1e20;

		Vector3 rel=p_to-p_from;
		real_t rel_l=rel.length();

		if (rel_l<CMP_EPSILON)
			return false;

		Vector3 dir=rel/rel_l;

		int min_index=-1;

		for (int i=0;i<p_plane_count;i++) {

			const Plane&p=p_planes[i];

			real_t den=p.normal.dot( dir );

			//printf("den is %i\n",den);
			if (Math::abs(den)<=CMP_EPSILON)
				continue; // ignore parallel plane


			real_t dist=-p.distance_to(p_from ) / den;

			if (den>0) {
				//backwards facing plane
				if (dist<max)
					max=dist;
			} else {

				//front facing plane
				if (dist>min) {
					min=dist;
					min_index=i;
				}
			}
		}

		if (max<=min || min<0 || min>rel_l || min_index==-1) // exit conditions
			return false; // no intersection

		if (p_res)
			*p_res=p_from+dir*min;
		if (p_norm)
			*p_norm=p_planes[min_index].normal;

		return true;
	}

	static Vector3 get_closest_point_to_segment(const Vector3& p_point, const Vector3 *p_segment) {

		Vector3 p=p_point-p_segment[0];
		Vector3 n=p_segment[1]-p_segment[0];
		float l =n.length();
		if (l<1e-10)
			return p_segment[0]; // both points are the same, just give any
		n/=l;
	
		float d=n.dot(p);
	
		if (d<=0.0)
			return p_segment[0]; // before first point
		else if (d>=l)
			return p_segment[1]; // after first point
		else
			return p_segment[0]+n*d; // inside
	}

	static Vector3 get_closest_point_to_segment_uncapped(const Vector3& p_point, const Vector3 *p_segment) {

		Vector3 p=p_point-p_segment[0];
		Vector3 n=p_segment[1]-p_segment[0];
		float l =n.length();
		if (l<1e-10)
			return p_segment[0]; // both points are the same, just give any
		n/=l;

		float d=n.dot(p);

		return p_segment[0]+n*d; // inside
	}

	static Vector2 get_closest_point_to_segment_2d(const Vector2& p_point, const Vector2 *p_segment) {

		Vector2 p=p_point-p_segment[0];
		Vector2 n=p_segment[1]-p_segment[0];
		float l =n.length();
		if (l<1e-10)
			return p_segment[0]; // both points are the same, just give any
		n/=l;

		float d=n.dot(p);

		if (d<=0.0)
			return p_segment[0]; // before first point
		else if (d>=l)
			return p_segment[1]; // after first point
		else
			return p_segment[0]+n*d; // inside
	}
	static Vector2 get_closest_point_to_segment_uncapped_2d(const Vector2& p_point, const Vector2 *p_segment) {

		Vector2 p=p_point-p_segment[0];
		Vector2 n=p_segment[1]-p_segment[0];
		float l =n.length();
		if (l<1e-10)
			return p_segment[0]; // both points are the same, just give any
		n/=l;

		float d=n.dot(p);

		return p_segment[0]+n*d; // inside
	}

	static bool segment_intersects_segment_2d(const Vector2& p_from_a,const Vector2& p_to_a,const Vector2& p_from_b,const Vector2& p_to_b,Vector2* r_result) {

		Vector2 B = p_to_a-p_from_a;
		Vector2 C = p_from_b-p_from_a;
		Vector2 D = p_to_b-p_from_a;

		real_t ABlen = B.dot(B);
		if (ABlen<=0)
			return false;
		Vector2 Bn = B/ABlen;
		C = Vector2( C.x*Bn.x + C.y*Bn.y, C.y*Bn.x - C.x*Bn.y );
		D = Vector2( D.x*Bn.x + D.y*Bn.y, D.y*Bn.x - D.x*Bn.y );

		if ((C.y<0 && D.y<0) || (C.y>=0 && D.y>=0))
			return false;

		float ABpos=D.x+(C.x-D.x)*D.y/(D.y-C.y);

		//  Fail if segment C-D crosses line A-B outside of segment A-B.
		if (ABpos<0 || ABpos>1.0)
			return false;

		//  (4) Apply the discovered position to line A-B in the original coordinate system.
		if (r_result)
			*r_result=p_from_a+B*ABpos;

		return true;
	}


	static inline bool point_in_projected_triangle(const Vector3& p_point,const Vector3& p_v1,const Vector3& p_v2,const Vector3& p_v3) {
	
	
		Vector3 face_n =  (p_v1-p_v3).cross(p_v1-p_v2);		
		
		Vector3 n1 =  (p_point-p_v3).cross(p_point-p_v2);		
		
		if (face_n.dot(n1)<0)
			return false;
			
		Vector3 n2 =  (p_v1-p_v3).cross(p_v1-p_point);		
		
		if (face_n.dot(n2)<0)
			return false;
		
		Vector3 n3 =  (p_v1-p_point).cross(p_v1-p_v2);		
	
		if (face_n.dot(n3)<0)
			return false;
	
		return true;
	
	}

	static inline bool triangle_sphere_intersection_test(const Vector3 *p_triangle,const Vector3& p_normal,const Vector3& p_sphere_pos, real_t p_sphere_radius,Vector3& r_triangle_contact,Vector3& r_sphere_contact) {

		float d=p_normal.dot(p_sphere_pos)-p_normal.dot(p_triangle[0]);

		if (d > p_sphere_radius || d < -p_sphere_radius) // not touching the plane of the face, return
			return false;

		Vector3 contact=p_sphere_pos - (p_normal*d);

		/** 2nd) TEST INSIDE TRIANGLE **/


		if (Geometry::point_in_projected_triangle(contact,p_triangle[0],p_triangle[1],p_triangle[2])) {
			r_triangle_contact=contact;
			r_sphere_contact=p_sphere_pos-p_normal*p_sphere_radius;
			//printf("solved inside triangle\n");
			return true;
		}

		/** 3rd TEST INSIDE EDGE CYLINDERS **/

		const Vector3 verts[4]={p_triangle[0],p_triangle[1],p_triangle[2],p_triangle[0]}; // for() friendly

		for (int i=0;i<3;i++) {

			// check edge cylinder

			Vector3 n1=verts[i]-verts[i+1];
			Vector3 n2=p_sphere_pos-verts[i+1];

			///@TODO i could discard by range here to make the algorithm quicker? dunno..

			// check point within cylinder radius
			Vector3 axis =n1.cross(n2).cross(n1);
			axis.normalize(); // ugh

			float ad=axis.dot(n2);

			if (ABS(ad)>p_sphere_radius) {
				// no chance with this edge, too far away
				continue;
			}

			// check point within edge capsule cylinder
			/** 4th TEST INSIDE EDGE POINTS **/

			float sphere_at = n1.dot(n2);

			if (sphere_at>=0 && sphere_at<n1.dot(n1)) {

				r_triangle_contact=p_sphere_pos-axis*(axis.dot(n2));
				r_sphere_contact=p_sphere_pos-axis*p_sphere_radius;
				// point inside here
				//printf("solved inside edge\n");
				return true;
			}

			float r2=p_sphere_radius*p_sphere_radius;

			if (n2.length_squared()<r2) {

				Vector3 n=(p_sphere_pos-verts[i+1]).normalized();

				//r_triangle_contact=verts[i+1]+n*p_sphere_radius;p_sphere_pos+axis*(p_sphere_radius-axis.dot(n2));
				r_triangle_contact=verts[i+1];
				r_sphere_contact=p_sphere_pos-n*p_sphere_radius;
				//printf("solved inside point segment 1\n");
				return true;
			}

			if (n2.distance_squared_to(n1)<r2) {
				Vector3 n=(p_sphere_pos-verts[i]).normalized();

				//r_triangle_contact=verts[i]+n*p_sphere_radius;p_sphere_pos+axis*(p_sphere_radius-axis.dot(n2));
				r_triangle_contact=verts[i];
				r_sphere_contact=p_sphere_pos-n*p_sphere_radius;
				//printf("solved inside point segment 1\n");
				return true;
			}

			break; // It's pointless to continue at this point, so save some cpu cycles
		}

		return false;
	}



	static real_t segment_intersects_circle(const Vector2& p_from, const Vector2& p_to, const Vector2& p_circle_pos, real_t p_circle_radius) {

			Vector2 line_vec = p_to - p_from;
			Vector2 vec_to_line = p_from - p_circle_pos;

			/* create a quadratic formula of the form ax^2 + bx + c = 0 */
			real_t a, b, c;

			a = line_vec.dot(line_vec);
			b = 2 * vec_to_line.dot(line_vec);
			c = vec_to_line.dot(vec_to_line) - p_circle_radius * p_circle_radius;

			/* solve for t */
			real_t sqrtterm = b*b - 4*a*c;

			/* if the term we intend to square root is less than 0 then the answer won't be real, so it definitely won't be t in the range 0 to 1 */
			if(sqrtterm < 0) return -1;

			/* if we can assume that the line segment starts outside the circle (e.g. for continuous time collision detection) then the following can be skipped and we can just return the equivalent of res1 */
			sqrtterm = Math::sqrt(sqrtterm);
			real_t res1 = ( -b - sqrtterm ) / (2 * a);
			//real_t res2 = ( -b + sqrtterm ) / (2 * a);

			return  (res1 >= 0 && res1 <= 1) ? res1 : -1;

	}


	static Vector<int> triangulate_polygon(const Vector<Vector2>& p_polygon) {

		Vector<int> triangles;
		if (!Triangulate::triangulate(p_polygon,triangles))
			return Vector<int>(); //fail
		return triangles;
	}

	static Vector< Vector<Vector2> > (*_decompose_func)(const Vector<Vector2>& p_polygon);
	static Vector< Vector<Vector2> > decompose_polygon(const Vector<Vector2>& p_polygon) {

		if (_decompose_func)
			return _decompose_func(p_polygon);

		return Vector< Vector<Vector2> >();

	}


	static DVector< DVector< Face3 > > separate_objects( DVector< Face3 > p_array );

	static DVector< Face3 > wrap_geometry( DVector< Face3 > p_array, float *p_error=NULL ); ///< create a "wrap" that encloses the given geometry


	struct MeshData {
		
		struct Face {
			Plane plane;
			Vector<int> indices;
		};
		
		Vector<Face> faces;
		
		struct Edge {
		
			int a,b;
		};
		
		Vector<Edge> edges;
		
		Vector< Vector3 > vertices;

		void optimize_vertices();
	};


	static MeshData build_convex_mesh(const DVector<Plane> &p_planes);
	static DVector<Plane> build_sphere_planes(float p_radius, int p_lats, int p_lons, Vector3::Axis p_axis=Vector3::AXIS_Z);
	static DVector<Plane> build_box_planes(const Vector3& p_extents);
	static DVector<Plane> build_cylinder_planes(float p_radius, float p_height, int p_sides, Vector3::Axis p_axis=Vector3::AXIS_Z);
	static DVector<Plane> build_capsule_planes(float p_radius, float p_height, int p_sides, int p_lats, Vector3::Axis p_axis=Vector3::AXIS_Z);
	
	
};



#endif