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// 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: 5.2.0 (2010/06/21)
#include "Colliders.h"
//----------------------------------------------------------------------------
Colliders::Colliders ()
{
SetDerivativeTimeStep(1e-03f);
SetPseudodistanceThreshold(1e-06f);
SetMaxIterations(8);
mContactTime = Mathf::MAX_REAL;
}
//----------------------------------------------------------------------------
Colliders::~Colliders ()
{
}
//----------------------------------------------------------------------------
void Colliders::SetDerivativeTimeStep (float timeStep)
{
if (timeStep > 0.0f)
{
mDerivativeTimeStep = timeStep;
}
else
{
mDerivativeTimeStep = 1e-03f;
}
mInvDerivativeTimeStep = 0.5f/mDerivativeTimeStep;
}
//----------------------------------------------------------------------------
float Colliders::GetDerivativeTimeStep () const
{
return mDerivativeTimeStep;
}
//----------------------------------------------------------------------------
void Colliders::SetPseudodistanceThreshold (float threshold)
{
if (threshold >= 0.0f)
{
mPseudodistanceThreshold = threshold;
}
}
//----------------------------------------------------------------------------
float Colliders::GetPseudodistanceThreshold () const
{
return mPseudodistanceThreshold;
}
//----------------------------------------------------------------------------
void Colliders::SetMaxIterations (int maxIterations)
{
if (maxIterations > 0)
{
mMaxIterations = maxIterations;
}
}
//----------------------------------------------------------------------------
int Colliders::GetMaxIterations () const
{
return mMaxIterations;
}
//----------------------------------------------------------------------------
Colliders::CollisionType Colliders::Test (float maxTime,
const Vector3f& velocity0, const Vector3f& velocity1, float& contactTime)
{
return Find(maxTime, velocity0, velocity1, contactTime);
}
//----------------------------------------------------------------------------
Colliders::CollisionType Colliders::Find (float maxTime,
const Vector3f& velocity0, const Vector3f& velocity1, float& contactTime)
{
float f0, fder0;
CollisionType type = FastNoIntersection(maxTime, velocity0, velocity1,
f0, fder0);
if (type == SEPARATED)
{
contactTime = Mathf::MAX_REAL;
return SEPARATED;
}
if (type == TOUCHING)
{
contactTime = 0.0f;
return TOUCHING;
}
// Use Newtons method for root finding when the derivative is calculated
// but Secant method when the derivative is estimated.
float t0 = 0.0f;
for (int i = 1; i <= mMaxIterations; ++i)
{
t0 -= f0/fder0;
if (t0 > maxTime)
{
// The objects do not intersect during the specified time
// interval.
contactTime = Mathf::MAX_REAL;
return TOUCHING;
}
f0 = Pseudodistance(t0, velocity0, velocity1);
if (f0 <= mPseudodistanceThreshold)
{
contactTime = t0;
ComputeContactInformation(TOUCHING, contactTime, velocity0,
velocity1);
return TOUCHING;
}
fder0 = PseudodistanceDerivative(t0, f0, velocity0, velocity1);
if (fder0 >= 0.0f)
{
// The objects are moving apart.
contactTime = Mathf::MAX_REAL;
return SEPARATED;
}
}
// Newtons method failed to converge, but we already tested earlier
// whether the objects were moving apart or not intersecting during the
// specified time interval. To reach here, the number of iterations was
// not large enough for the desired pseudodistance threshold. Most
// likely this occurs when the relative speed is very large and the time
// step for the derivative estimation needs to be smaller.
contactTime = t0;
ComputeContactInformation(TOUCHING, contactTime, velocity0, velocity1);
return TOUCHING;
}
//----------------------------------------------------------------------------
float Colliders::GetContactTime () const
{
return mContactTime;
}
//----------------------------------------------------------------------------
float Colliders::PseudodistanceDerivative (float t0, float f0,
const Vector3f& velocity0, const Vector3f& velocity1) const
{
float t1 = t0 - mDerivativeTimeStep;
float f1 = Pseudodistance(t1,velocity0,velocity1);
float fder0 = (f0 - f1)*mInvDerivativeTimeStep;
return fder0;
}
//----------------------------------------------------------------------------
Colliders::CollisionType Colliders::FastNoIntersection (float maxTime,
const Vector3f& velocity0, const Vector3f& velocity1, float& f0,
float& fder0)
{
// Analyze the initial configuration of the objects.
f0 = Pseudodistance(0.0f, velocity0, velocity1);
fder0 = PseudodistanceDerivative(0.0f, f0, velocity0, velocity1);
if (f0 <= -mPseudodistanceThreshold)
{
// Objects are (significantly) overlapping.
ComputeContactInformation(OVERLAPPING, 0.0f, velocity0, velocity1);
return (fder0 >= 0.0f ? SEPARATED : OVERLAPPING);
}
if (f0 <= mPseudodistanceThreshold)
{
// Objects are (nearly) in tangential contact.
ComputeContactInformation(TOUCHING, 0.0f, velocity0, velocity1);
return (fder0 >= 0.0f ? SEPARATED : TOUCHING);
}
// The objects are not currently in contact or overlapping. If the
// objects are moving apart or the relative velocity between them is
// zero, they cannot intersect at a later time.
if (fder0 >= 0.0f || velocity0 == velocity1)
{
return SEPARATED;
}
// Check if the objects are not intersecting, yet still moving toward each
// other at maximum time. If this is the case, the objects do not
// intersect on the specified time interval.
float f1 = Pseudodistance(maxTime, velocity0, velocity1);
if (f1 > 0.0f)
{
// Compute or estimate the derivative F(tmax).
float fder1 = PseudodistanceDerivative(maxTime, f1, velocity0,
velocity1);
if (fder1 < 0.0f)
{
// The objects are moving toward each other and do not intersect
// during the specified time interval.
return SEPARATED;
}
}
return UNKNOWN;
}
//----------------------------------------------------------------------------
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