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Diffstat (limited to 'extern/bullet2/src/BulletDynamics/Featherstone/btMultiBodyLink.h')
| -rw-r--r-- | extern/bullet2/src/BulletDynamics/Featherstone/btMultiBodyLink.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/extern/bullet2/src/BulletDynamics/Featherstone/btMultiBodyLink.h b/extern/bullet2/src/BulletDynamics/Featherstone/btMultiBodyLink.h new file mode 100644 index 00000000000..fbd54c45db3 --- /dev/null +++ b/extern/bullet2/src/BulletDynamics/Featherstone/btMultiBodyLink.h @@ -0,0 +1,110 @@ +/* +Bullet Continuous Collision Detection and Physics Library +Copyright (c) 2013 Erwin Coumans http://bulletphysics.org + +This software is provided 'as-is', without any express or implied warranty. +In no event will the authors be held liable for any damages arising from the use of this software. +Permission is granted to anyone to use this software for any purpose, +including commercial applications, and to alter it and redistribute it freely, +subject to the following restrictions: + +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. +2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. +3. This notice may not be removed or altered from any source distribution. +*/ + +#ifndef BT_MULTIBODY_LINK_H +#define BT_MULTIBODY_LINK_H + +#include "LinearMath/btQuaternion.h" +#include "LinearMath/btVector3.h" +#include "BulletCollision/CollisionDispatch/btCollisionObject.h" + +enum btMultiBodyLinkFlags +{ + BT_MULTIBODYLINKFLAGS_DISABLE_PARENT_COLLISION = 1 +}; +// +// Link struct +// + +struct btMultibodyLink +{ + + BT_DECLARE_ALIGNED_ALLOCATOR(); + + btScalar joint_pos; // qi + + btScalar mass; // mass of link + btVector3 inertia; // inertia of link (local frame; diagonal) + + int parent; // index of the parent link (assumed to be < index of this link), or -1 if parent is the base link. + + btQuaternion zero_rot_parent_to_this; // rotates vectors in parent-frame to vectors in local-frame (when q=0). constant. + + // "axis" = spatial joint axis (Mirtich Defn 9 p104). (expressed in local frame.) constant. + // for prismatic: axis_top = zero; + // axis_bottom = unit vector along the joint axis. + // for revolute: axis_top = unit vector along the rotation axis (u); + // axis_bottom = u cross d_vector. + btVector3 axis_top; + btVector3 axis_bottom; + + btVector3 d_vector; // vector from the inboard joint pos to this link's COM. (local frame.) constant. set for revolute joints only. + + // e_vector is constant, but depends on the joint type + // prismatic: vector from COM of parent to COM of this link, WHEN Q = 0. (local frame.) + // revolute: vector from parent's COM to the pivot point, in PARENT's frame. + btVector3 e_vector; + + bool is_revolute; // true = revolute, false = prismatic + + btQuaternion cached_rot_parent_to_this; // rotates vectors in parent frame to vectors in local frame + btVector3 cached_r_vector; // vector from COM of parent to COM of this link, in local frame. + + btVector3 applied_force; // In WORLD frame + btVector3 applied_torque; // In WORLD frame + btScalar joint_torque; + + class btMultiBodyLinkCollider* m_collider; + int m_flags; + + // ctor: set some sensible defaults + btMultibodyLink() + : joint_pos(0), + mass(1), + parent(-1), + zero_rot_parent_to_this(1, 0, 0, 0), + is_revolute(false), + cached_rot_parent_to_this(1, 0, 0, 0), + joint_torque(0), + m_collider(0), + m_flags(0) + { + inertia.setValue(1, 1, 1); + axis_top.setValue(0, 0, 0); + axis_bottom.setValue(1, 0, 0); + d_vector.setValue(0, 0, 0); + e_vector.setValue(0, 0, 0); + cached_r_vector.setValue(0, 0, 0); + applied_force.setValue( 0, 0, 0); + applied_torque.setValue(0, 0, 0); + } + + // routine to update cached_rot_parent_to_this and cached_r_vector + void updateCache() + { + if (is_revolute) + { + cached_rot_parent_to_this = btQuaternion(axis_top,-joint_pos) * zero_rot_parent_to_this; + cached_r_vector = d_vector + quatRotate(cached_rot_parent_to_this,e_vector); + } else + { + // cached_rot_parent_to_this never changes, so no need to update + cached_r_vector = e_vector + joint_pos * axis_bottom; + } + } +}; + + +#endif //BT_MULTIBODY_LINK_H |