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Diffstat (limited to 'Source/OpenEXR/Imath/ImathSphere.h')
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diff --git a/Source/OpenEXR/Imath/ImathSphere.h b/Source/OpenEXR/Imath/ImathSphere.h new file mode 100644 index 0000000..3860701 --- /dev/null +++ b/Source/OpenEXR/Imath/ImathSphere.h @@ -0,0 +1,177 @@ +/////////////////////////////////////////////////////////////////////////// +// +// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas +// Digital Ltd. LLC +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Industrial Light & Magic nor the names of +// its contributors may be used to endorse or promote products derived +// from this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +/////////////////////////////////////////////////////////////////////////// + + + +#ifndef INCLUDED_IMATHSPHERE_H +#define INCLUDED_IMATHSPHERE_H + +//------------------------------------- +// +// A 3D sphere class template +// +//------------------------------------- + +#include "ImathVec.h" +#include "ImathBox.h" +#include "ImathLine.h" + +namespace Imath { + +template <class T> +class Sphere3 +{ + public: + + Vec3<T> center; + T radius; + + //--------------- + // Constructors + //--------------- + + Sphere3() : center(0,0,0), radius(0) {} + Sphere3(const Vec3<T> &c, T r) : center(c), radius(r) {} + + //------------------------------------------------------------------- + // Utilities: + // + // s.circumscribe(b) sets center and radius of sphere s + // so that the s tightly encloses box b. + // + // s.intersectT (l, t) If sphere s and line l intersect, then + // intersectT() computes the smallest t, + // t >= 0, so that l(t) is a point on the + // sphere. intersectT() then returns true. + // + // If s and l do not intersect, intersectT() + // returns false. + // + // s.intersect (l, i) If sphere s and line l intersect, then + // intersect() calls s.intersectT(l,t) and + // computes i = l(t). + // + // If s and l do not intersect, intersect() + // returns false. + // + //------------------------------------------------------------------- + + void circumscribe(const Box<Vec3<T> > &box); + bool intersect(const Line3<T> &l, Vec3<T> &intersection) const; + bool intersectT(const Line3<T> &l, T &t) const; +}; + + +//-------------------- +// Convenient typedefs +//-------------------- + +typedef Sphere3<float> Sphere3f; +typedef Sphere3<double> Sphere3d; + + +//--------------- +// Implementation +//--------------- + +template <class T> +void Sphere3<T>::circumscribe(const Box<Vec3<T> > &box) +{ + center = T(0.5) * (box.min + box.max); + radius = (box.max - center).length(); +} + + +template <class T> +bool Sphere3<T>::intersectT(const Line3<T> &line, T &t) const +{ + bool doesIntersect = true; + + Vec3<T> v = line.pos - center; + T B = 2.0 * (line.dir ^ v); + T C = (v ^ v) - (radius * radius); + + // compute discriminant + // if negative, there is no intersection + + T discr = B*B - 4.0*C; + + if (discr < 0.0) + { + // line and Sphere3 do not intersect + + doesIntersect = false; + } + else + { + // t0: (-B - sqrt(B^2 - 4AC)) / 2A (A = 1) + + T sqroot = Math<T>::sqrt(discr); + t = (-B - sqroot) * 0.5; + + if (t < 0.0) + { + // no intersection, try t1: (-B + sqrt(B^2 - 4AC)) / 2A (A = 1) + + t = (-B + sqroot) * 0.5; + } + + if (t < 0.0) + doesIntersect = false; + } + + return doesIntersect; +} + + +template <class T> +bool Sphere3<T>::intersect(const Line3<T> &line, Vec3<T> &intersection) const +{ + T t; + + if (intersectT (line, t)) + { + intersection = line(t); + return true; + } + else + { + return false; + } +} + + +} //namespace Imath + +#endif |