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/*
* SOLID - Software Library for Interference Detection
*
* Copyright (C) 2001-2003 Dtecta. All rights reserved.
*
* This library may be distributed under the terms of the Q Public License
* (QPL) as defined by Trolltech AS of Norway and appearing in the file
* LICENSE.QPL included in the packaging of this file.
*
* This library may be distributed and/or modified under the terms of the
* GNU General Public License (GPL) version 2 as published by the Free Software
* Foundation and appearing in the file LICENSE.GPL included in the
* packaging of this file.
*
* This library is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Commercial use or any other use of this library not covered by either
* the QPL or the GPL requires an additional license from Dtecta.
* Please contact info@dtecta.com for enquiries about the terms of commercial
* use of this library.
*/
#include "DT_Sphere.h"
#include "GEN_MinMax.h"
MT_Scalar DT_Sphere::supportH(const MT_Vector3& v) const
{
return m_radius * v.length();
}
MT_Point3 DT_Sphere::support(const MT_Vector3& v) const
{
MT_Scalar s = v.length();
if (s > MT_Scalar(0.0))
{
s = m_radius / s;
return MT_Point3(v[0] * s, v[1] * s, v[2] * s);
}
else
{
return MT_Point3(m_radius, MT_Scalar(0.0), MT_Scalar(0.0));
}
}
bool DT_Sphere::ray_cast(const MT_Point3& source, const MT_Point3& target,
MT_Scalar& param, MT_Vector3& normal) const
{
MT_Vector3 r = target - source;
MT_Scalar delta = -source.dot(r);
MT_Scalar r_length2 = r.length2();
MT_Scalar sigma = delta * delta - r_length2 * (source.length2() - m_radius * m_radius);
if (sigma >= MT_Scalar(0.0))
// The line trough source and target intersects the sphere.
{
MT_Scalar sqrt_sigma = MT_sqrt(sigma);
// We need only the sign of lambda2, so the division by the positive
// r_length2 can be left out.
MT_Scalar lambda2 = (delta + sqrt_sigma) /* / r_length2 */ ;
if (lambda2 >= MT_Scalar(0.0))
// The ray points at the sphere
{
MT_Scalar lambda1 = (delta - sqrt_sigma) / r_length2;
if (lambda1 <= param)
// The ray hits the sphere, since
// [lambda1, lambda2] overlaps [0, param].
{
if (lambda1 > MT_Scalar(0.0))
{
param = lambda1;
normal = (source + r * lambda1) / m_radius;
// NB: division by m_radius to normalize the normal.
}
else
{
param = MT_Scalar(0.0);
normal.setValue(MT_Scalar(0.0), MT_Scalar(0.0), MT_Scalar(0.0));
}
return true;
}
}
}
return false;
}
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