74 lines
2.2 KiB
C++
74 lines
2.2 KiB
C++
// Filename: LinearFrictionForce.cxx
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// Created by: charles (23Jun00)
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//
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////////////////////////////////////////////////////////////////////
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#include "linearFrictionForce.h"
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TypeHandle LinearFrictionForce::_type_handle;
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////////////////////////////////////////////////////////////////////
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// Function : LinearFrictionForce
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// Access : Public
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// Description : Constructor
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////////////////////////////////////////////////////////////////////
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LinearFrictionForce::
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LinearFrictionForce(float coef, float a, bool m) :
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LinearForce(a, m) {
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// friction REALLY shouldn't be outside of [0, 1]
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if (coef < 0.0f)
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coef = 0.0f;
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else if (coef > 1.0f)
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coef = 1.0f;
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_coef = coef;
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}
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////////////////////////////////////////////////////////////////////
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// Function : LinearFrictionForce
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// Access : Public
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// Description : copy constructor
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////////////////////////////////////////////////////////////////////
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LinearFrictionForce::
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LinearFrictionForce(const LinearFrictionForce ©) :
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LinearForce(copy) {
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_coef = copy._coef;
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}
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////////////////////////////////////////////////////////////////////
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// Function : LinearFrictionForce
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// Access : Public
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// Description : destructor
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////////////////////////////////////////////////////////////////////
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LinearFrictionForce::
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~LinearFrictionForce(void) {
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}
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////////////////////////////////////////////////////////////////////
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// Function : make_copy
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// Access : Public
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// Description : copier
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////////////////////////////////////////////////////////////////////
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LinearForce *LinearFrictionForce::
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make_copy(void) {
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return new LinearFrictionForce(*this);
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}
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////////////////////////////////////////////////////////////////////
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// Function : LinearFrictionForce
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// Access : Public
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// Description : Constructor
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////////////////////////////////////////////////////////////////////
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LVector3f LinearFrictionForce::
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get_child_vector(const PhysicsObject* po) {
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LVector3f v = po->get_velocity();
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LVector3f friction = -v * (1.0f - _coef);
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// cary said to cap this at zero so that friction can't reverse
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// your direction, but it seems to me that if you're computing:
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// v + (-v * _coef), _coef in [0, 1]
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// that this will always be greater than or equal to zero.
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return friction;
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}
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