normalizing_policy.h

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** 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.
 *  
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 *  Copyright (C) 2004-2011 the Initial Developer.
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 */
 
 
/** @defgroup NormalizingPolicy NormalizingPolicy
 *  @brief policies to specify if direction vectors (and normals) should be normalized.
 *  @author Bram de Greve
 *  @date 2003
 *
 *  For direction vectors and normal vectors, you can be in the situation you want to
 *  have them normalized (unit length) and that you want this to be done automatically.
 *  Or you can be in the situation where you want them to be anything but normalized.
 *  These policies will let you set this.
 *
 *  The content of the policies are rather implementation details, clients shouldn't
 *  worry about it.
 *
 *  @note these policies can be used for vectors of any dimension.
 */
 
/** @struct lass::prim::Normalized
 *  @ingroup NormalizingPolicy
 *  @brief Policy to auto-normalize normals.
 *  @author Bram de Greve [BdG]
 *  @date 2003
 *
 *  Using this policy will automatically normalize all direction vectors and normals.
 *  That way, you don't have to bother what you have as input, you know that they will
 *  be normalized anyway.  Also, for the implementation of the primitives, optimized
 *  routines are provided that take advantage of the knowledge that the vectors are
 *  normalized.  But this are implementation details you should not worry about.
 */
 
/** @struct lass::prim::Unnormalized
 *  @ingroup NormalizingPolicy
 *  @brief Policy to keep normals unnormalized.
 *  @author Bram de Greve [BdG]
 *  @date 2003
 *
 *  Using this policy will keep direction vectors and normals at their original length.
 *  You can do this for precision reasons, for speed issues, or any other reason that
 *  is yours.  However, the maths will still be correct, because the implementations
 *  will know of this unnormalized vectors, and will correct with extra factors where
 *  necessary.  But, these corrections can sometimes be faster than using normalized
 *  vectors for start, because they often can avoid the square root.
 */
 
/** @struct lass::prim::IsAlreadyNormalized
 *  @ingroup NormalizingPolicy
 *  @date 2006
 *
 *  Empty argument to tell a function the client assures the vector coming in is already
 *  normalized, so the function doesn't has to.
 */
 
#ifndef LASS_GUARDIAN_OF_INCLUSION_PRIM_NORMALIZING_POLICY_H
#define LASS_GUARDIAN_OF_INCLUSION_PRIM_NORMALIZING_POLICY_H
 
#include "prim_common.h"
 
 
 
namespace lass
{
 
namespace prim
{
 
struct Normalized
{
    /** Normalize a vector iSubject
     */
    template<typename VectorType>
    static void normalize(VectorType& ioSubject)
    {
        ioSubject.normalize();
    }
 
    /** Normalize iSubject, and scale iExtraValue as well so iExtraValue / iSubject.norm() is constant.
     *  Typically used by cartesian equations.
     *  @post iExtraValue / iSubject.norm() is the same as before the call.
     */
    template<typename VectorType, typename ValueType>
    static void normalizeAndScale(VectorType& ioSubject, ValueType& ioExtraValue)
    {
        const typename VectorType::TValue norm = ioSubject.norm();
        LASS_ASSERT(norm != VectorType::TNumTraits::zero);
        ioExtraValue /= norm;
        ioSubject /= norm;
    }
 
    /** since iNormObject should be normalized by now, we can "divide by 1".
     *  @return iValue
     *  @pre iNormObject is supposed to be normalized!
     */
    template<typename ValueType, typename VectorType>
    static ValueType divideByNorm(ValueType iValue, const VectorType& /*iNormObject*/)
    {
        return iValue;
    }
 
    /** since iNormObject should be normalized by now, we can "divide by 1".
     *  @return iValue
     *  @pre iNormObject is supposed to be normalized!
     */
    template<typename ValueType, typename VectorType>
    static ValueType divideBySquaredNorm(ValueType iValue, const VectorType& /*iNormObject*/)
    {
        return iValue;
    }
};
 
 
 
struct Unnormalized
{
    /** Don't normalize normals we want to keep unnormalized! :)
     *  this is a noop.
     */
    template<typename VectorType>
    static void normalize(VectorType& /*ioSubject*/)
    {
    }
 
 
    /** Don't normalize and don't scale
     */
    template<typename VectorType, typename ValueType>
    static void normalizeAndScale(VectorType& /*ioSubject*/, ValueType& /*ioExtraValue*/)
    {
    }
 
    /** @return iValue divided by the norm of iNormObject
     */
    template<typename ValueType, typename VectorType>
    static ValueType divideByNorm(ValueType iValue, const VectorType& iNormObject)
    {
        return iValue / iNormObject.norm();
    }
 
    /** @return iValue divided by the squared norm of iNormObject
     */
    template<typename ValueType, typename VectorType>
    static ValueType divideBySquaredNorm(ValueType iValue, const VectorType& iNormObject)
    {
        return iValue / iNormObject.squaredNorm();
    }
};
 
 
 
struct IsAlreadyNormalized
{
};
 
 
 
 
}
 
}
 
#endif