Bullet Collision Detection & Physics Library
btClipPolygon.h
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1 #ifndef BT_CLIP_POLYGON_H_INCLUDED
2 #define BT_CLIP_POLYGON_H_INCLUDED
3 
7 /*
8 This source file is part of GIMPACT Library.
9 
10 For the latest info, see http://gimpact.sourceforge.net/
11 
12 Copyright (c) 2007 Francisco Leon Najera. C.C. 80087371.
13 email: projectileman@yahoo.com
14 
15 
16 This software is provided 'as-is', without any express or implied warranty.
17 In no event will the authors be held liable for any damages arising from the use of this software.
18 Permission is granted to anyone to use this software for any purpose,
19 including commercial applications, and to alter it and redistribute it freely,
20 subject to the following restrictions:
21 
22 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
23 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
24 3. This notice may not be removed or altered from any source distribution.
25 */
26 
27 #include "LinearMath/btTransform.h"
29 
30 
32 {
33  return point.dot(plane) - plane[3];
34 }
35 
38 SIMD_FORCE_INLINE void bt_vec_blend(btVector3 &vr, const btVector3 &va,const btVector3 &vb, btScalar blend_factor)
39 {
40  vr = (1-blend_factor)*va + blend_factor*vb;
41 }
42 
45  const btVector3 & point0,
46  const btVector3 & point1,
47  btScalar dist0,
48  btScalar dist1,
49  btVector3 * clipped,
50  int & clipped_count)
51 {
52  bool _prevclassif = (dist0>SIMD_EPSILON);
53  bool _classif = (dist1>SIMD_EPSILON);
54  if(_classif!=_prevclassif)
55  {
56  btScalar blendfactor = -dist0/(dist1-dist0);
57  bt_vec_blend(clipped[clipped_count],point0,point1,blendfactor);
58  clipped_count++;
59  }
60  if(!_classif)
61  {
62  clipped[clipped_count] = point1;
63  clipped_count++;
64  }
65 }
66 
67 
69 
73  const btVector4 & plane,
74  const btVector3 * polygon_points,
75  int polygon_point_count,
76  btVector3 * clipped)
77 {
78  int clipped_count = 0;
79 
80 
81  //clip first point
82  btScalar firstdist = bt_distance_point_plane(plane,polygon_points[0]);;
83  if(!(firstdist>SIMD_EPSILON))
84  {
85  clipped[clipped_count] = polygon_points[0];
86  clipped_count++;
87  }
88 
89  btScalar olddist = firstdist;
90  for(int i=1;i<polygon_point_count;i++)
91  {
92  btScalar dist = bt_distance_point_plane(plane,polygon_points[i]);
93 
95  polygon_points[i-1],polygon_points[i],
96  olddist,
97  dist,
98  clipped,
99  clipped_count);
100 
101 
102  olddist = dist;
103  }
104 
105  //RETURN TO FIRST point
106 
108  polygon_points[polygon_point_count-1],polygon_points[0],
109  olddist,
110  firstdist,
111  clipped,
112  clipped_count);
113 
114  return clipped_count;
115 }
116 
118 
123  const btVector4 & plane,
124  const btVector3 & point0,
125  const btVector3 & point1,
126  const btVector3& point2,
127  btVector3 * clipped // an allocated array of 16 points at least
128  )
129 {
130  int clipped_count = 0;
131 
132  //clip first point0
133  btScalar firstdist = bt_distance_point_plane(plane,point0);;
134  if(!(firstdist>SIMD_EPSILON))
135  {
136  clipped[clipped_count] = point0;
137  clipped_count++;
138  }
139 
140  // point 1
141  btScalar olddist = firstdist;
142  btScalar dist = bt_distance_point_plane(plane,point1);
143 
145  point0,point1,
146  olddist,
147  dist,
148  clipped,
149  clipped_count);
150 
151  olddist = dist;
152 
153 
154  // point 2
155  dist = bt_distance_point_plane(plane,point2);
156 
158  point1,point2,
159  olddist,
160  dist,
161  clipped,
162  clipped_count);
163  olddist = dist;
164 
165 
166 
167  //RETURN TO FIRST point0
169  point2,point0,
170  olddist,
171  firstdist,
172  clipped,
173  clipped_count);
174 
175  return clipped_count;
176 }
177 
178 
179 
180 
181 
182 #endif // GIM_TRI_COLLISION_H_INCLUDED
#define SIMD_EPSILON
Definition: btScalar.h:494
#define SIMD_FORCE_INLINE
Definition: btScalar.h:63
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
int bt_plane_clip_triangle(const btVector4 &plane, const btVector3 &point0, const btVector3 &point1, const btVector3 &point2, btVector3 *clipped)
Clips a polygon by a plane.
btScalar bt_distance_point_plane(const btVector4 &plane, const btVector3 &point)
Definition: btClipPolygon.h:31
void bt_vec_blend(btVector3 &vr, const btVector3 &va, const btVector3 &vb, btScalar blend_factor)
Definition: btClipPolygon.h:38
int bt_plane_clip_polygon(const btVector4 &plane, const btVector3 *polygon_points, int polygon_point_count, btVector3 *clipped)
Clips a polygon by a plane.
Definition: btClipPolygon.h:72
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
void bt_plane_clip_polygon_collect(const btVector3 &point0, const btVector3 &point1, btScalar dist0, btScalar dist1, btVector3 *clipped, int &clipped_count)
This function calcs the distance from a 3D plane.
Definition: btClipPolygon.h:44
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:278