openscenegraph
AngularDampingOperator
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1/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2010 Robert Osfield
2 *
3 * This library is open source and may be redistributed and/or modified under
4 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
5 * (at your option) any later version. The full license is in LICENSE file
6 * included with this distribution, and on the openscenegraph.org website.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * OpenSceneGraph Public License for more details.
12*/
13// Written by Wang Rui, (C) 2010
14
15#ifndef OSGPARTICLE_ANGULARDAMPINGOPERATOR
16#define OSGPARTICLE_ANGULARDAMPINGOPERATOR
17
18#include <osgParticle/Operator>
19#include <osgParticle/Particle>
20
21namespace osgParticle
22{
23
24
25/** A angular damping operator applies damping constant to particle's angular velocity.
26 Refer to David McAllister's Particle System API (http://www.particlesystems.org)
27*/
28class AngularDampingOperator : public Operator
29{
30public:
31 AngularDampingOperator() : Operator(), _cutoffLow(0.0f), _cutoffHigh(FLT_MAX)
32 {}
33
34 AngularDampingOperator( const AngularDampingOperator& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY )
35 : Operator(copy, copyop), _damping(copy._damping),
36 _cutoffLow(copy._cutoffLow), _cutoffHigh(copy._cutoffHigh)
37 {}
38
39 META_Object( osgParticle, AngularDampingOperator );
40
41 /// Set the damping factors
42 void setDamping( float x, float y, float z ) { _damping.set(x, y, z); }
43 void setDamping( const osg::Vec3& damping ) { _damping = damping; }
44
45 /// Set the damping factors to one value
46 void setDamping( float x ) { _damping.set(x, x, x); }
47
48 /// Get the damping factors
49 void getDamping( float& x, float& y, float& z ) const
50 { x = _damping.x(); y = _damping.y(); z = _damping.z(); }
51
52 const osg::Vec3& getDamping() const { return _damping; }
53
54 /// Set the velocity cutoff factors
55 void setCutoff( float low, float high ) { _cutoffLow = low; _cutoffHigh = high; }
56 void setCutoffLow( float low ) { _cutoffLow = low; }
57 void setCutoffHigh( float low ) { _cutoffHigh = low; }
58
59 /// Get the velocity cutoff factors
60 void getCutoff( float& low, float& high ) const { low = _cutoffLow; high = _cutoffHigh; }
61 float getCutoffLow() const { return _cutoffLow; }
62 float getCutoffHigh() const { return _cutoffHigh; }
63
64 /// Apply the acceleration to a particle. Do not call this method manually.
65 inline void operate( Particle* P, double dt );
66
67protected:
68 virtual ~AngularDampingOperator() {}
69 AngularDampingOperator& operator=( const AngularDampingOperator& ) { return *this; }
70
71 osg::Vec3 _damping;
72 float _cutoffLow;
73 float _cutoffHigh;
74};
75
76// INLINE METHODS
77
78inline void AngularDampingOperator::operate( Particle* P, double dt )
79{
80 const osg::Vec3& vel = P->getAngularVelocity();
81 float length2 = vel.length2();
82 if ( length2>=_cutoffLow && length2<=_cutoffHigh )
83 {
84 osg::Vec3 newvel( vel.x() * (1.0f - (1.0f - _damping.x()) * dt),
85 vel.y() * (1.0f - (1.0f - _damping.y()) * dt),
86 vel.z() * (1.0f - (1.0f - _damping.z()) * dt) );
87 P->setAngularVelocity( newvel );
88 }
89}
90
91
92}
93
94#endif