Geo_Sphere.h

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#ifndef SimTK_SIMMATH_GEO_SPHERE_H_
#define SimTK_SIMMATH_GEO_SPHERE_H_

/* -------------------------------------------------------------------------- *
 *                        Simbody(tm): SimTKmath                              *
 * -------------------------------------------------------------------------- *
 * This is part of the SimTK biosimulation toolkit originating from           *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org/home/simbody.  *
 *                                                                            *
 * Portions copyright (c) 2011-12 Stanford University and the Authors.        *
 * Authors: Michael Sherman                                                   *
 * Contributors:                                                              *
 *                                                                            *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may    *
 * not use this file except in compliance with the License. You may obtain a  *
 * copy of the License at http://www.apache.org/licenses/LICENSE-2.0.         *
 *                                                                            *
 * Unless required by applicable law or agreed to in writing, software        *
 * distributed under the License is distributed on an "AS IS" BASIS,          *
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   *
 * See the License for the specific language governing permissions and        *
 * limitations under the License.                                             *
 * -------------------------------------------------------------------------- */

#include "SimTKcommon.h"
#include "simmath/internal/common.h"
#include "simmath/internal/Geo.h"

#include <cassert>
#include <cmath>
#include <algorithm>

namespace SimTK {


//==============================================================================
//                              GEO SPHERE
//==============================================================================
template <class P>
class Geo::Sphere_ {
typedef P           RealP;
typedef Vec<3,P>    Vec3P;
typedef Vec<4,P>    Vec4P;
public:
Sphere_() {}
Sphere_(const Vec3P& center, RealP radius)
:   cr(center[0], center[1], center[2], radius) {assert(radius>=0);}
Sphere_& setRadius(RealP radius) 
{   assert(radius>=0); cr[3]=radius; return *this; }
Sphere_& setCenter(const Vec3P& center) 
{   Vec3P::updAs(&cr[0])=center; return *this; }

Sphere_& scaleBy(RealP f)
{   setRadius(f*getRadius()); return *this; }

Sphere_& stretchBoundary() {
    const RealP tol = Geo::getDefaultTol<P>();
    const RealP maxdim = max(getCenter().abs());
    const RealP scale = std::max(maxdim, getRadius());
    updRadius() += std::max(scale*Geo::getEps<P>(), tol);
    return *this; 
}

RealP findVolume() const 
{   return (RealP(4)/3) * NTraits<P>::getPi() * cube(getRadius()); }
RealP findArea() const 
{   return 4 * NTraits<P>::getPi() * square(getRadius()); }

bool isPointOutside(const Vec3P& p) const {
    const RealP r2 = Geo::Point_<P>::findDistanceSqr(p, getCenter());
    return r2 > square(getRadius());
}
bool isPointOutside(const Vec3P& p, RealP tol) const {
    assert(tol >= 0);
    const RealP r2 = Geo::Point_<P>::findDistanceSqr(p, getCenter());
    return r2 > square(getRadius()+tol);
}
const Vec3P& getCenter() const {return Vec3P::getAs(&cr[0]);}
Vec3P& updCenter() {return Vec3P::updAs(&cr[0]);}
RealP getRadius() const {return cr[3];}
RealP& updRadius() {return cr[3];}


private:
// Store together to make sure the compiler doesn't introduce any padding.
// cr[0..2] is the center point, cr[3] is the radius
Vec4P   cr;    
};


} // namespace SimTK

#endif // SimTK_SIMMATH_GEO_SPHERE_H_