1 #ifndef BT_CLIP_POLYGON_H_INCLUDED
2 #define BT_CLIP_POLYGON_H_INCLUDED
3
4 /*! \file btClipPolygon.h
5 \author Francisco Leon Najera
6 */
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"
28 #include "LinearMath/btGeometryUtil.h"
29
30
bt_distance_point_plane(const btVector4 & plane,const btVector3 & point)31 SIMD_FORCE_INLINE btScalar bt_distance_point_plane(const btVector4 & plane,const btVector3 &point)
32 {
33 return point.dot(plane) - plane[3];
34 }
35
36 /*! Vector blending
37 Takes two vectors a, b, blends them together*/
bt_vec_blend(btVector3 & vr,const btVector3 & va,const btVector3 & vb,btScalar blend_factor)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
43 //! This function calcs the distance from a 3D plane
bt_plane_clip_polygon_collect(const btVector3 & point0,const btVector3 & point1,btScalar dist0,btScalar dist1,btVector3 * clipped,int & clipped_count)44 SIMD_FORCE_INLINE void bt_plane_clip_polygon_collect(
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
68 //! Clips a polygon by a plane
69 /*!
70 *\return The count of the clipped counts
71 */
bt_plane_clip_polygon(const btVector4 & plane,const btVector3 * polygon_points,int polygon_point_count,btVector3 * clipped)72 SIMD_FORCE_INLINE int bt_plane_clip_polygon(
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
94 bt_plane_clip_polygon_collect(
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
107 bt_plane_clip_polygon_collect(
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
117 //! Clips a polygon by a plane
118 /*!
119 *\param clipped must be an array of 16 points.
120 *\return The count of the clipped counts
121 */
bt_plane_clip_triangle(const btVector4 & plane,const btVector3 & point0,const btVector3 & point1,const btVector3 & point2,btVector3 * clipped)122 SIMD_FORCE_INLINE int bt_plane_clip_triangle(
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
144 bt_plane_clip_polygon_collect(
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
157 bt_plane_clip_polygon_collect(
158 point1,point2,
159 olddist,
160 dist,
161 clipped,
162 clipped_count);
163 olddist = dist;
164
165
166
167 //RETURN TO FIRST point0
168 bt_plane_clip_polygon_collect(
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
183