Bullet Collision Detection & Physics Library: btMultiBodyLink.h Source File

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btMultiBodyLink.h
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1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2013 Erwin Coumans http://bulletphysics.org
4
5 This software is provided 'as-is', without any express or implied warranty.
6 In no event will the authors be held liable for any damages arising from the use of this software.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10
11 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.
12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
13 3. This notice may not be removed or altered from any source distribution.
14 */
15
16 #ifndef BT_MULTIBODY_LINK_H
17 #define BT_MULTIBODY_LINK_H
18
19 #include "LinearMath/btQuaternion.h"
20 #include "LinearMath/btVector3.h"
21 #include "BulletCollision/CollisionDispatch/btCollisionObject.h"
22
23 enum btMultiBodyLinkFlags
24 {
25 BT_MULTIBODYLINKFLAGS_DISABLE_PARENT_COLLISION = 1
26 };
27
28 //both defines are now permanently enabled
29 #define BT_MULTIBODYLINK_INCLUDE_PLANAR_JOINTS
30 #define TEST_SPATIAL_ALGEBRA_LAYER
31
32 //
33 // Various spatial helper functions
34 //
35
36 //namespace {
37
38
39 #include "LinearMath/btSpatialAlgebra.h"
40
41 //}
42
43 //
44 // Link struct
45 //
46
47 struct btMultibodyLink
48 {
49
50 BT_DECLARE_ALIGNED_ALLOCATOR();
51
52 btScalar m_mass; // mass of link
53 btVector3 m_inertiaLocal; // inertia of link (local frame; diagonal)
54
55 int m_parent; // index of the parent link (assumed to be < index of this link), or -1 if parent is the base link.
56
57 btQuaternion m_zeroRotParentToThis; // rotates vectors in parent-frame to vectors in local-frame (when q=0). constant.
58
59 btVector3 m_dVector; // vector from the inboard joint pos to this link's COM. (local frame.) constant.
60 //this is set to zero for planar joint (see also m_eVector comment)
61
62 // m_eVector is constant, but depends on the joint type:
63 // revolute, fixed, prismatic, spherical: vector from parent's COM to the pivot point, in PARENT's frame.
64 // planar: vector from COM of parent to COM of this link, WHEN Q = 0. (local frame.)
65 // todo: fix the planar so it is consistent with the other joints
66
67 btVector3 m_eVector;
68
69 btSpatialMotionVector m_absFrameTotVelocity, m_absFrameLocVelocity;
70
71 enum eFeatherstoneJointType
72 {
73 eRevolute = 0,
74 ePrismatic = 1,
75 eSpherical = 2,
76 ePlanar = 3,
77 eFixed = 4,
78 eInvalid
79 };
80
81
82
83 // "axis" = spatial joint axis (Mirtich Defn 9 p104). (expressed in local frame.) constant.
84 // for prismatic: m_axesTop[0] = zero;
85 // m_axesBottom[0] = unit vector along the joint axis.
86 // for revolute: m_axesTop[0] = unit vector along the rotation axis (u);
87 // m_axesBottom[0] = u cross m_dVector (i.e. COM linear motion due to the rotation at the joint)
88 //
89 // for spherical: m_axesTop[0][1][2] (u1,u2,u3) form a 3x3 identity matrix (3 rotation axes)
90 // m_axesBottom[0][1][2] cross u1,u2,u3 (i.e. COM linear motion due to the rotation at the joint)
91 //
92 // for planar: m_axesTop[0] = unit vector along the rotation axis (u); defines the plane of motion
93 // m_axesTop[1][2] = zero
94 // m_axesBottom[0] = zero
95 // m_axesBottom[1][2] = unit vectors along the translational axes on that plane
96 btSpatialMotionVector m_axes[6];
97 void setAxisTop(int dof, const btVector3 &axis) { m_axes[dof].m_topVec = axis; }
98 void setAxisBottom(int dof, const btVector3 &axis) { m_axes[dof].m_bottomVec = axis; }
99 void setAxisTop(int dof, const btScalar &x, const btScalar &y, const btScalar &z) { m_axes[dof].m_topVec.setValue(x, y, z); }
100 void setAxisBottom(int dof, const btScalar &x, const btScalar &y, const btScalar &z) { m_axes[dof].m_bottomVec.setValue(x, y, z); }
101 const btVector3 & getAxisTop(int dof) const { return m_axes[dof].m_topVec; }
102 const btVector3 & getAxisBottom(int dof) const { return m_axes[dof].m_bottomVec; }
103
104 int m_dofOffset, m_cfgOffset;
105
106 btQuaternion m_cachedRotParentToThis; // rotates vectors in parent frame to vectors in local frame
107 btVector3 m_cachedRVector; // vector from COM of parent to COM of this link, in local frame.
108
109 btVector3 m_appliedForce; // In WORLD frame
110 btVector3 m_appliedTorque; // In WORLD frame
111
112 btVector3 m_appliedConstraintForce; // In WORLD frame
113 btVector3 m_appliedConstraintTorque; // In WORLD frame
114
115 btScalar m_jointPos[7];
116
117 //m_jointTorque is the joint torque applied by the user using 'addJointTorque'.
118 //It gets set to zero after each internal stepSimulation call
119 btScalar m_jointTorque[6];
120
121 class btMultiBodyLinkCollider* m_collider;
122 int m_flags;
123
124
125 int m_dofCount, m_posVarCount; //redundant but handy
126
127 eFeatherstoneJointType m_jointType;
128
129 struct btMultiBodyJointFeedback* m_jointFeedback;
130
131 btTransform m_cachedWorldTransform;//this cache is updated when calling btMultiBody::forwardKinematics
132
133 const char* m_linkName;//m_linkName memory needs to be managed by the developer/user!
134 const char* m_jointName;//m_jointName memory needs to be managed by the developer/user!
135
136 // ctor: set some sensible defaults
137 btMultibodyLink()
138 : m_mass(1),
139 m_parent(-1),
140 m_zeroRotParentToThis(0, 0, 0, 1),
141 m_cachedRotParentToThis(0, 0, 0, 1),
142 m_collider(0),
143 m_flags(0),
144 m_dofCount(0),
145 m_posVarCount(0),
146 m_jointType(btMultibodyLink::eInvalid),
147 m_jointFeedback(0),
148 m_linkName(0),
149 m_jointName(0)
150 {
151
152 m_inertiaLocal.setValue(1, 1, 1);
153 setAxisTop(0, 0., 0., 0.);
154 setAxisBottom(0, 1., 0., 0.);
155 m_dVector.setValue(0, 0, 0);
156 m_eVector.setValue(0, 0, 0);
157 m_cachedRVector.setValue(0, 0, 0);
158 m_appliedForce.setValue( 0, 0, 0);
159 m_appliedTorque.setValue(0, 0, 0);
160 //
161 m_jointPos[0] = m_jointPos[1] = m_jointPos[2] = m_jointPos[4] = m_jointPos[5] = m_jointPos[6] = 0.f;
162 m_jointPos[3] = 1.f; //"quat.w"
163 m_jointTorque[0] = m_jointTorque[1] = m_jointTorque[2] = m_jointTorque[3] = m_jointTorque[4] = m_jointTorque[5] = 0.f;
164 m_cachedWorldTransform.setIdentity();
165 }
166
167 // routine to update m_cachedRotParentToThis and m_cachedRVector
168 void updateCacheMultiDof(btScalar *pq = 0)
169 {
170 btScalar *pJointPos = (pq ? pq : &m_jointPos[0]);
171
172 switch(m_jointType)
173 {
174 case eRevolute:
175 {
176 m_cachedRotParentToThis = btQuaternion(getAxisTop(0),-pJointPos[0]) * m_zeroRotParentToThis;
177 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
178
179 break;
180 }
181 case ePrismatic:
182 {
183 // m_cachedRotParentToThis never changes, so no need to update
184 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector) + pJointPos[0] * getAxisBottom(0);
185
186 break;
187 }
188 case eSpherical:
189 {
190 m_cachedRotParentToThis = btQuaternion(pJointPos[0], pJointPos[1], pJointPos[2], -pJointPos[3]) * m_zeroRotParentToThis;
191 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
192
193 break;
194 }
195 case ePlanar:
196 {
197 m_cachedRotParentToThis = btQuaternion(getAxisTop(0),-pJointPos[0]) * m_zeroRotParentToThis;
198 m_cachedRVector = quatRotate(btQuaternion(getAxisTop(0),-pJointPos[0]), pJointPos[1] * getAxisBottom(1) + pJointPos[2] * getAxisBottom(2)) + quatRotate(m_cachedRotParentToThis,m_eVector);
199
200 break;
201 }
202 case eFixed:
203 {
204 m_cachedRotParentToThis = m_zeroRotParentToThis;
205 m_cachedRVector = m_dVector + quatRotate(m_cachedRotParentToThis,m_eVector);
206
207 break;
208 }
209 default:
210 {
211 //invalid type
212 btAssert(0);
213 }
214 }
215 }
216 };
217
218
219 #endif //BT_MULTIBODY_LINK_H
btMultibodyLink::m_zeroRotParentToThis
btQuaternion m_zeroRotParentToThis
Definition: btMultiBodyLink.h:57
btMultiBodyLinkFlags
btMultiBodyLinkFlags
Definition: btMultiBodyLink.h:23
btMultibodyLink::getAxisBottom
const btVector3 & getAxisBottom(int dof) const
Definition: btMultiBodyLink.h:102
btMultibodyLink::m_appliedConstraintForce
btVector3 m_appliedConstraintForce
Definition: btMultiBodyLink.h:112
btVector3::setValue
void setValue(const btScalar &_x, const btScalar &_y, const btScalar &_z)
Definition: btVector3.h:640
btVector3.h
BT_MULTIBODYLINKFLAGS_DISABLE_PARENT_COLLISION
Definition: btMultiBodyLink.h:25
btMultibodyLink::eRevolute
Definition: btMultiBodyLink.h:73
btMultibodyLink::m_cachedRVector
btVector3 m_cachedRVector
Definition: btMultiBodyLink.h:107
btMultibodyLink::m_jointType
eFeatherstoneJointType m_jointType
Definition: btMultiBodyLink.h:127
btMultibodyLink::m_collider
class btMultiBodyLinkCollider * m_collider
Definition: btMultiBodyLink.h:121
btMultibodyLink::updateCacheMultiDof
void updateCacheMultiDof(btScalar *pq=0)
Definition: btMultiBodyLink.h:168
btTransform::setIdentity
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
btAssert
#define btAssert(x)
Definition: btScalar.h:113
btMultibodyLink::setAxisTop
void setAxisTop(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
Definition: btMultiBodyLink.h:99
btMultibodyLink::m_posVarCount
int m_posVarCount
Definition: btMultiBodyLink.h:125
btMultibodyLink::m_absFrameLocVelocity
btSpatialMotionVector m_absFrameLocVelocity
Definition: btMultiBodyLink.h:69
btMultibodyLink::m_jointName
const char * m_jointName
Definition: btMultiBodyLink.h:134
btMultibodyLink::m_cfgOffset
int m_cfgOffset
Definition: btMultiBodyLink.h:104
btMultibodyLink
Definition: btMultiBodyLink.h:47
btMultiBodyJointFeedback
Definition: btMultiBodyJointFeedback.h:22
btMultibodyLink::btMultibodyLink
btMultibodyLink()
Definition: btMultiBodyLink.h:137
btMultibodyLink::m_dVector
btVector3 m_dVector
Definition: btMultiBodyLink.h:59
quatRotate
btVector3 quatRotate(const btQuaternion &rotation, const btVector3 &v)
Definition: btQuaternion.h:884
btMultibodyLink::eFixed
Definition: btMultiBodyLink.h:77
btSpatialAlgebra.h
btMultibodyLink::m_jointTorque
btScalar m_jointTorque[6]
Definition: btMultiBodyLink.h:119
btQuaternion.h
btMultibodyLink::m_dofCount
int m_dofCount
Definition: btMultiBodyLink.h:125
btMultibodyLink::m_cachedRotParentToThis
btQuaternion m_cachedRotParentToThis
Definition: btMultiBodyLink.h:106
btMultibodyLink::eFeatherstoneJointType
eFeatherstoneJointType
Definition: btMultiBodyLink.h:71
btMultibodyLink::m_axes
btSpatialMotionVector m_axes[6]
Definition: btMultiBodyLink.h:96
btMultibodyLink::m_linkName
const char * m_linkName
Definition: btMultiBodyLink.h:133
btMultibodyLink::m_mass
btScalar m_mass
Definition: btMultiBodyLink.h:52
btMultibodyLink::setAxisBottom
void setAxisBottom(int dof, const btVector3 &axis)
Definition: btMultiBodyLink.h:98
btSpatialMotionVector::m_bottomVec
btVector3 m_bottomVec
Definition: btSpatialAlgebra.h:70
btSpatialMotionVector
Definition: btSpatialAlgebra.h:68
btMultibodyLink::m_eVector
btVector3 m_eVector
Definition: btMultiBodyLink.h:67
btMultibodyLink::m_jointPos
btScalar m_jointPos[7]
Definition: btMultiBodyLink.h:115
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btMultibodyLink::m_dofOffset
int m_dofOffset
Definition: btMultiBodyLink.h:104
btMultibodyLink::m_appliedTorque
btVector3 m_appliedTorque
Definition: btMultiBodyLink.h:110
btMultibodyLink::eSpherical
Definition: btMultiBodyLink.h:75
btMultibodyLink::eInvalid
Definition: btMultiBodyLink.h:78
btMultibodyLink::m_flags
int m_flags
Definition: btMultiBodyLink.h:122
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btMultibodyLink::m_absFrameTotVelocity
btSpatialMotionVector m_absFrameTotVelocity
Definition: btMultiBodyLink.h:69
btMultiBodyLinkCollider
Definition: btMultiBodyLinkCollider.h:23
btMultibodyLink::m_appliedConstraintTorque
btVector3 m_appliedConstraintTorque
Definition: btMultiBodyLink.h:113
btSpatialMotionVector::m_topVec
btVector3 m_topVec
Definition: btSpatialAlgebra.h:70
btMultibodyLink::BT_DECLARE_ALIGNED_ALLOCATOR
BT_DECLARE_ALIGNED_ALLOCATOR()
btCollisionObject.h
btMultibodyLink::m_cachedWorldTransform
btTransform m_cachedWorldTransform
Definition: btMultiBodyLink.h:131
btMultibodyLink::setAxisTop
void setAxisTop(int dof, const btVector3 &axis)
Definition: btMultiBodyLink.h:97
btQuaternion
The btQuaternion implements quaternion to perform linear algebra rotations in combination with btMatr...
Definition: btQuaternion.h:55
btMultibodyLink::m_jointFeedback
struct btMultiBodyJointFeedback * m_jointFeedback
Definition: btMultiBodyLink.h:129
btMultibodyLink::m_inertiaLocal
btVector3 m_inertiaLocal
Definition: btMultiBodyLink.h:53
btMultibodyLink::m_appliedForce
btVector3 m_appliedForce
Definition: btMultiBodyLink.h:109
btMultibodyLink::getAxisTop
const btVector3 & getAxisTop(int dof) const
Definition: btMultiBodyLink.h:101
btMultibodyLink::setAxisBottom
void setAxisBottom(int dof, const btScalar &x, const btScalar &y, const btScalar &z)
Definition: btMultiBodyLink.h:100
btMultibodyLink::ePlanar
Definition: btMultiBodyLink.h:76
btMultibodyLink::ePrismatic
Definition: btMultiBodyLink.h:74
btMultibodyLink::m_parent
int m_parent
Definition: btMultiBodyLink.h:55
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:278