1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.0 (2010/01/01)
#ifndef PHYSICSMODULE_H
#define PHYSICSMODULE_H
#include "Wm5MassSpringCurve.h"
using namespace Wm5;
class PhysicsModule : public MassSpringCurve3f
{
public:
// Construction and destruction.
//
// Gravity is controlled by the input 'gravity'.
//
// Mass-spring systems tend to exhibit "stiffness" (in the sense of
// numerical stability). To remedy this problem, a small amount of
// viscous friction is added to the external force. This term is
// of the form -viscosity*velocity where viscosity > 0.
//
// The initial wind force is specified by the caller. The application
// of wind can be enabled/disabled by EnableWind(). The member
// function EnableWindChange() allows the wind direction to change
// randomly, but each new direction is nearby the old direction in order
// to obtain some sense of continuity of direction. The magnitude of
// the wind force is constant, the length of the initial force.
PhysicsModule (int numParticles, float step, const Vector3f& gravity,
const Vector3f& wind, float windChangeAmplitude, float viscosity);
bool EnableWind;
bool EnableWindChange;
// External acceleration is due to forces of gravitation, wind, and
// viscous friction. The wind forces are randomly generated.
virtual Vector3f ExternalAcceleration (int i, float time,
const Vector3f* positions, const Vector3f* velocities);
protected:
Vector3f mGravity, mWind;
float mWindChangeAmplitude, mViscosity;
};
#endif
|
