Blame Imath/ImathSphere.h

Packit 8dc392
///////////////////////////////////////////////////////////////////////////
Packit 8dc392
//
Packit 8dc392
// Copyright (c) 2002-2012, Industrial Light & Magic, a division of Lucas
Packit 8dc392
// Digital Ltd. LLC
Packit 8dc392
// 
Packit 8dc392
// All rights reserved.
Packit 8dc392
// 
Packit 8dc392
// Redistribution and use in source and binary forms, with or without
Packit 8dc392
// modification, are permitted provided that the following conditions are
Packit 8dc392
// met:
Packit 8dc392
// *       Redistributions of source code must retain the above copyright
Packit 8dc392
// notice, this list of conditions and the following disclaimer.
Packit 8dc392
// *       Redistributions in binary form must reproduce the above
Packit 8dc392
// copyright notice, this list of conditions and the following disclaimer
Packit 8dc392
// in the documentation and/or other materials provided with the
Packit 8dc392
// distribution.
Packit 8dc392
// *       Neither the name of Industrial Light & Magic nor the names of
Packit 8dc392
// its contributors may be used to endorse or promote products derived
Packit 8dc392
// from this software without specific prior written permission. 
Packit 8dc392
// 
Packit 8dc392
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
Packit 8dc392
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
Packit 8dc392
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
Packit 8dc392
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
Packit 8dc392
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
Packit 8dc392
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
Packit 8dc392
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
Packit 8dc392
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
Packit 8dc392
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
Packit 8dc392
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
Packit 8dc392
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Packit 8dc392
//
Packit 8dc392
///////////////////////////////////////////////////////////////////////////
Packit 8dc392
Packit 8dc392
Packit 8dc392
Packit 8dc392
#ifndef INCLUDED_IMATHSPHERE_H
Packit 8dc392
#define INCLUDED_IMATHSPHERE_H
Packit 8dc392
Packit 8dc392
//-------------------------------------
Packit 8dc392
//
Packit 8dc392
//	A 3D sphere class template
Packit 8dc392
//
Packit 8dc392
//-------------------------------------
Packit 8dc392
Packit 8dc392
#include "ImathVec.h"
Packit 8dc392
#include "ImathBox.h"
Packit 8dc392
#include "ImathLine.h"
Packit 8dc392
#include "ImathNamespace.h"
Packit 8dc392
Packit 8dc392
IMATH_INTERNAL_NAMESPACE_HEADER_ENTER
Packit 8dc392
Packit 8dc392
template <class T>
Packit 8dc392
class Sphere3
Packit 8dc392
{
Packit 8dc392
  public:
Packit 8dc392
Packit 8dc392
    Vec3<T>	center;
Packit 8dc392
    T           radius;
Packit 8dc392
Packit 8dc392
    //---------------
Packit 8dc392
    //	Constructors
Packit 8dc392
    //---------------
Packit 8dc392
Packit 8dc392
    Sphere3() : center(0,0,0), radius(0) {}
Packit 8dc392
    Sphere3(const Vec3<T> &c, T r) : center(c), radius(r) {}
Packit 8dc392
Packit 8dc392
    //-------------------------------------------------------------------
Packit 8dc392
    //	Utilities:
Packit 8dc392
    //
Packit 8dc392
    //	s.circumscribe(b)	sets center and radius of sphere s
Packit 8dc392
    //				so that the s tightly encloses box b.
Packit 8dc392
    //
Packit 8dc392
    //	s.intersectT (l, t)	If sphere s and line l intersect, then
Packit 8dc392
    //				intersectT() computes the smallest t,
Packit 8dc392
    //				t >= 0, so that l(t) is a point on the
Packit 8dc392
    //				sphere.  intersectT() then returns true.
Packit 8dc392
    //
Packit 8dc392
    //				If s and l do not intersect, intersectT()
Packit 8dc392
    //				returns false.
Packit 8dc392
    //
Packit 8dc392
    //	s.intersect (l, i)	If sphere s and line l intersect, then
Packit 8dc392
    //				intersect() calls s.intersectT(l,t) and
Packit 8dc392
    //				computes i = l(t).
Packit 8dc392
    //
Packit 8dc392
    //				If s and l do not intersect, intersect()
Packit 8dc392
    //				returns false.
Packit 8dc392
    //
Packit 8dc392
    //-------------------------------------------------------------------
Packit 8dc392
Packit 8dc392
    void circumscribe(const Box<Vec3<T> > &box);
Packit 8dc392
    bool intersect(const Line3<T> &l, Vec3<T> &intersection) const;
Packit 8dc392
    bool intersectT(const Line3<T> &l, T &t) const;
Packit 8dc392
};
Packit 8dc392
Packit 8dc392
Packit 8dc392
//--------------------
Packit 8dc392
// Convenient typedefs
Packit 8dc392
//--------------------
Packit 8dc392
Packit 8dc392
typedef Sphere3<float> Sphere3f;
Packit 8dc392
typedef Sphere3<double> Sphere3d;
Packit 8dc392
Packit 8dc392
Packit 8dc392
//---------------
Packit 8dc392
// Implementation
Packit 8dc392
//---------------
Packit 8dc392
Packit 8dc392
template <class T>
Packit 8dc392
void Sphere3<T>::circumscribe(const Box<Vec3<T> > &box)
Packit 8dc392
{
Packit 8dc392
    center = T(0.5) * (box.min + box.max);
Packit 8dc392
    radius = (box.max - center).length();
Packit 8dc392
}
Packit 8dc392
Packit 8dc392
Packit 8dc392
template <class T>
Packit 8dc392
bool Sphere3<T>::intersectT(const Line3<T> &line, T &t) const
Packit 8dc392
{
Packit 8dc392
    bool doesIntersect = true;
Packit 8dc392
Packit 8dc392
    Vec3<T> v = line.pos - center;
Packit 8dc392
    T B = T(2.0) * (line.dir ^ v);
Packit 8dc392
    T C = (v ^ v) - (radius * radius);
Packit 8dc392
Packit 8dc392
    // compute discriminant
Packit 8dc392
    // if negative, there is no intersection
Packit 8dc392
Packit 8dc392
    T discr = B*B - T(4.0)*C;
Packit 8dc392
Packit 8dc392
    if (discr < 0.0)
Packit 8dc392
    {
Packit 8dc392
	// line and Sphere3 do not intersect
Packit 8dc392
Packit 8dc392
	doesIntersect = false;
Packit 8dc392
    }
Packit 8dc392
    else
Packit 8dc392
    {
Packit 8dc392
	// t0: (-B - sqrt(B^2 - 4AC)) / 2A  (A = 1)
Packit 8dc392
Packit 8dc392
	T sqroot = Math<T>::sqrt(discr);
Packit 8dc392
	t = (-B - sqroot) * T(0.5);
Packit 8dc392
Packit 8dc392
	if (t < 0.0)
Packit 8dc392
	{
Packit 8dc392
	    // no intersection, try t1: (-B + sqrt(B^2 - 4AC)) / 2A  (A = 1)
Packit 8dc392
Packit 8dc392
	    t = (-B + sqroot) * T(0.5);
Packit 8dc392
	}
Packit 8dc392
Packit 8dc392
	if (t < 0.0)
Packit 8dc392
	    doesIntersect = false;
Packit 8dc392
    }
Packit 8dc392
Packit 8dc392
    return doesIntersect;
Packit 8dc392
}
Packit 8dc392
Packit 8dc392
Packit 8dc392
template <class T>
Packit 8dc392
bool Sphere3<T>::intersect(const Line3<T> &line, Vec3<T> &intersection) const
Packit 8dc392
{
Packit 8dc392
    T t;
Packit 8dc392
Packit 8dc392
    if (intersectT (line, t))
Packit 8dc392
    {
Packit 8dc392
	intersection = line(t);
Packit 8dc392
	return true;
Packit 8dc392
    }
Packit 8dc392
    else
Packit 8dc392
    {
Packit 8dc392
	return false;
Packit 8dc392
    }
Packit 8dc392
}
Packit 8dc392
Packit 8dc392
IMATH_INTERNAL_NAMESPACE_HEADER_EXIT
Packit 8dc392
Packit 8dc392
#endif // INCLUDED_IMATHSPHERE_H