ray_3d_transformation_3d.h

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
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 *  *** END LICENSE INFORMATION ***
 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_RAY_3D_TRANSFORMATION_3D_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_RAY_3D_TRANSFORMATION_3D_H

#include "prim_common.h"
#include "ray_3d.h"
#include "transformation_3d.h"

namespace lass
{
namespace prim
{

namespace impl
{
    template <typename NP> struct RayParameterRescaler;

    template <>
    struct RayParameterRescaler<prim::Unnormalized>
    {
        // unnormalized directions don't alter parameter: same t is same point
        template <typename T, typename VectorType> 
        static void rescale(T& tRay, const VectorType& unnormalizedNewDirection) 
        { 
        }
    };

    template <>
    struct RayParameterRescaler<prim::Normalized>
    {
        // normalized ray's compress parameters because of renormalisation of direction.
        // to get same point, scale parameter by norm before renormalisation.
        template <typename T, typename VectorType> 
        static void rescale(T& tRay, const VectorType& unnormalizedNewDirection) 
        {
            tRay *= unnormalizedNewDirection.norm();
        }
    };
}



/** apply transformation to ray
 *  @relates Transformation3D
 */
template<typename T, class NP, class PP>
Ray3D<T, NP, PP> transform(
        const Ray3D<T, NP, PP>& subject, const Transformation3D<T>& transformation)
{
    return Ray3D<T, NP, PP>(
        transform(subject.support(), transformation),
        transform(subject.direction(), transformation));
}



/** apply transformation to ray, and rescale a parameter to represent same point
 *
 *  @param tRay
 *      - INPUT & OUTPUT
 *      - if direction gets renormalized, then a point on ray is no longer represented
 *        by same parameter.  Adjust parameter @a tRay to fix this.
 *      - If you fill in 1 as @a tRay, you can use the result to
 *        rescale multiple parameters by multiplying it.
 *      - <tt>transform(ray, transf).point(t') == transform(ray.point(t), transf)</tt>
 *
 *  @relates Transformation3D
 */
template<typename T, class NP, class PP>
Ray3D<T, NP, PP> transform(
        const Ray3D<T, NP, PP>& subject, const Transformation3D<T>& transformation, T& tRay)
{
    typedef Ray3D<T, NP, PP> TRay;
    const typename TRay::TPoint support = transform(subject.support(), transformation);
    const typename TRay::TVector direction = transform(subject.direction(), transformation);
    impl::RayParameterRescaler<NP>::rescale(tRay, direction);
    return Ray3D<T, NP, PP>(support, direction);;
}

}
}

#endif

// EOF