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

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btDeformableGravityForce.h
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1/*
2 Written by Xuchen Han <xuchenhan2015@u.northwestern.edu>
3
4 Bullet Continuous Collision Detection and Physics Library
5 Copyright (c) 2019 Google Inc. http://bulletphysics.org
6 This software is provided 'as-is', without any express or implied warranty.
7 In no event will the authors be held liable for any damages arising from the use of this software.
8 Permission is granted to anyone to use this software for any purpose,
9 including commercial applications, and to alter it and redistribute it freely,
10 subject to the following restrictions:
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_DEFORMABLE_GRAVITY_FORCE_H
17#define BT_DEFORMABLE_GRAVITY_FORCE_H
18
19#include "btDeformableLagrangianForce.h"
20
21 class btDeformableGravityForce : public btDeformableLagrangianForce
22{
23public:
24 typedef btAlignedObjectArray<btVector3> TVStack;
25 btVector3 m_gravity;
26
27 btDeformableGravityForce(const btVector3& g) : m_gravity(g)
28 {
29 }
30
31 virtual void addScaledForces(btScalar scale, TVStack& force)
32 {
33 addScaledGravityForce(scale, force);
34 }
35
36 virtual void addScaledExplicitForce(btScalar scale, TVStack& force)
37 {
38 addScaledGravityForce(scale, force);
39 }
40
41 virtual void addScaledDampingForce(btScalar scale, TVStack& force)
42 {
43 }
44
45 virtual void addScaledElasticForceDifferential(btScalar scale, const TVStack& dx, TVStack& df)
46 {
47 }
48
49 virtual void addScaledDampingForceDifferential(btScalar scale, const TVStack& dv, TVStack& df)
50 {
51 }
52
53 virtual void buildDampingForceDifferentialDiagonal(btScalar scale, TVStack& diagA) {}
54
55 virtual void addScaledGravityForce(btScalar scale, TVStack& force)
56 {
57 int numNodes = getNumNodes();
58 btAssert(numNodes <= force.size());
59 for (int i = 0; i < m_softBodies.size(); ++i)
60 {
61 btSoftBody* psb = m_softBodies[i];
62 if (!psb->isActive())
63 {
64 continue;
65 }
66 for (int j = 0; j < psb->m_nodes.size(); ++j)
67 {
68 btSoftBody::Node& n = psb->m_nodes[j];
69 size_t id = n.index;
70 btScalar mass = (n.m_im == 0) ? 0 : 1. / n.m_im;
71 btVector3 scaled_force = scale * m_gravity * mass * m_softBodies[i]->m_gravityFactor;
72 force[id] += scaled_force;
73 }
74 }
75 }
76
77 virtual btDeformableLagrangianForceType getForceType()
78 {
79 return BT_GRAVITY_FORCE;
80 }
81
82 // the gravitational potential energy
83 virtual double totalEnergy(btScalar dt)
84 {
85 double e = 0;
86 for (int i = 0; i < m_softBodies.size(); ++i)
87 {
88 btSoftBody* psb = m_softBodies[i];
89 if (!psb->isActive())
90 {
91 continue;
92 }
93 for (int j = 0; j < psb->m_nodes.size(); ++j)
94 {
95 const btSoftBody::Node& node = psb->m_nodes[j];
96 if (node.m_im > 0)
97 {
98 e -= m_gravity.dot(node.m_q) / node.m_im;
99 }
100 }
101 }
102 return e;
103 }
104};
105#endif /* BT_DEFORMABLE_GRAVITY_FORCE_H */
btDeformableLagrangianForce.h
btDeformableLagrangianForceType
btDeformableLagrangianForceType
Definition: btDeformableLagrangianForce.h:24
BT_GRAVITY_FORCE
@ BT_GRAVITY_FORCE
Definition: btDeformableLagrangianForce.h:25
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
btAssert
#define btAssert(x)
Definition: btScalar.h:153
btAlignedObjectArray
The btAlignedObjectArray template class uses a subset of the stl::vector interface for its methods It...
Definition: btAlignedObjectArray.h:46
btAlignedObjectArray::size
int size() const
return the number of elements in the array
Definition: btAlignedObjectArray.h:142
btCollisionObject::isActive
bool isActive() const
Definition: btCollisionObject.h:306
btDeformableGravityForce
Definition: btDeformableGravityForce.h:22
btDeformableGravityForce::totalEnergy
virtual double totalEnergy(btScalar dt)
Definition: btDeformableGravityForce.h:83
btDeformableGravityForce::m_gravity
btVector3 m_gravity
Definition: btDeformableGravityForce.h:25
btDeformableGravityForce::getForceType
virtual btDeformableLagrangianForceType getForceType()
Definition: btDeformableGravityForce.h:77
btDeformableGravityForce::addScaledGravityForce
virtual void addScaledGravityForce(btScalar scale, TVStack &force)
Definition: btDeformableGravityForce.h:55
btDeformableGravityForce::addScaledElasticForceDifferential
virtual void addScaledElasticForceDifferential(btScalar scale, const TVStack &dx, TVStack &df)
Definition: btDeformableGravityForce.h:45
btDeformableGravityForce::addScaledForces
virtual void addScaledForces(btScalar scale, TVStack &force)
Definition: btDeformableGravityForce.h:31
btDeformableGravityForce::buildDampingForceDifferentialDiagonal
virtual void buildDampingForceDifferentialDiagonal(btScalar scale, TVStack &diagA)
Definition: btDeformableGravityForce.h:53
btDeformableGravityForce::addScaledDampingForce
virtual void addScaledDampingForce(btScalar scale, TVStack &force)
Definition: btDeformableGravityForce.h:41
btDeformableGravityForce::TVStack
btAlignedObjectArray< btVector3 > TVStack
Definition: btDeformableGravityForce.h:24
btDeformableGravityForce::addScaledExplicitForce
virtual void addScaledExplicitForce(btScalar scale, TVStack &force)
Definition: btDeformableGravityForce.h:36
btDeformableGravityForce::btDeformableGravityForce
btDeformableGravityForce(const btVector3 &g)
Definition: btDeformableGravityForce.h:27
btDeformableGravityForce::addScaledDampingForceDifferential
virtual void addScaledDampingForceDifferential(btScalar scale, const TVStack &dv, TVStack &df)
Definition: btDeformableGravityForce.h:49
btDeformableLagrangianForce
Definition: btDeformableLagrangianForce.h:39
btDeformableLagrangianForce::getNumNodes
virtual int getNumNodes()
Definition: btDeformableLagrangianForce.h:78
btDeformableLagrangianForce::m_softBodies
btAlignedObjectArray< btSoftBody * > m_softBodies
Definition: btDeformableLagrangianForce.h:42
btSoftBody
The btSoftBody is an class to simulate cloth and volumetric soft bodies.
Definition: btSoftBody.h:75
btSoftBody::m_nodes
tNodeArray m_nodes
Definition: btSoftBody.h:814
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:82
btVector3::dot
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:229
btSoftBody::Node
Definition: btSoftBody.h:268
btSoftBody::Node::m_im
btScalar m_im
Definition: btSoftBody.h:275
btSoftBody::Node::m_q
btVector3 m_q
Definition: btSoftBody.h:270
btSoftBody::Node::index
int index
Definition: btSoftBody.h:280