array_gradient2.h

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/*
**  array_gradient2.h
**
**  This is part of Shiokaze, a research-oriented fluid solver for computer graphics.
**  Created by Ryoichi Ando <rand@nii.ac.jp> on Sep 22, 2018.
**
**  Permission is hereby granted, free of charge, to any person obtaining a copy of
**  this software and associated documentation files (the "Software"), to deal in
**  the Software without restriction, including without limitation the rights to use,
**  copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
**  Software, and to permit persons to whom the Software is furnished to do so,
**  subject to the following conditions:
**
**  The above copyright notice and this permission notice shall be included in all copies
**  or substantial portions of the Software.
**
**  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
**  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
**  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
**  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
**  CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
**  OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
//
#ifndef SHKZ_ARRAY_GRADIENT2_H
#define SHKZ_ARRAY_GRADIENT2_H
//
#include "array2.h"
#include "macarray2.h"
//
SHKZ_BEGIN_NAMESPACE
//
namespace array_gradient2 {
    //
    template<class T> void compute_gradient( const array2<T> &array, macarray2<T> &gradient, double dx ) {
        for( int dim : DIMS2 ) {
            gradient[dim].clear();
            gradient[dim].activate_as(array,vec2i(0,0));
            gradient[dim].activate_as(array,vec2i(dim==0,dim==1));
        }
        shape2 shape = array.shape();
        gradient.parallel_actives([&]( int dim, int i, int j, auto &it, int tn ) {
            it.set(
                (array(shape.clamp(i,j))
                -array(shape.clamp(i-(dim==0),j-(dim==1)))
                )/dx);
        });
    }
};
//
SHKZ_END_NAMESPACE
//
#endif
//