basic_math.cpp

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/*
The MIT License (MIT)
 
Copyright (c) 2014 Mitsuaki KAWAMURA
 
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.
*/
/**@file
@brief Mathematical operations used in various step
*/
#if defined(HAVE_CONFIG_H)
#include <config.h>
#endif
#if defined(HAVE_GL_GL_H)
#include <GL/gl.h>
#elif defined(HAVE_OPENGL_GL_H)
#include <OpenGL/gl.h>
#endif
 
#include <cmath>
 
#if defined(_OPENMP)
#include <omp.h>
#endif
 
/**
 @brief Work as Modulo function of fortran
 @return Modulated value
*/
int modulo(
  int i, //!< [in]
  int n //!< [in]
) {
  int j;
  j = (i + 100 * n) % n;
  return j;
}/*modulo(int i, int n)*/
/**
 @brief Solve linear system
 @return Determinant
*/
GLfloat solve3(
  GLfloat a[3][3], //!< [in] Matix
  GLfloat b[3] //!< [in,out] Right hand side vector
)
{
  int i;
  GLfloat det, c[3];
  /**/
  det = a[0][0] * (a[1][1] * a[2][2] - a[1][2] * a[2][1])
      + a[0][1] * (a[1][2] * a[2][0] - a[1][0] * a[2][2])
      + a[0][2] * (a[1][0] * a[2][1] - a[1][1] * a[2][0]);
  /**/
  c[0] = b[0] * (a[1][1] * a[2][2] - a[1][2] * a[2][1])
       + b[1] * (a[0][2] * a[2][1] - a[0][1] * a[2][2])
       + b[2] * (a[0][1] * a[1][2] - a[0][2] * a[1][1]);
  /**/
  c[1] = b[0] * (a[1][2] * a[2][0] - a[1][0] * a[2][2])
       + b[1] * (a[0][0] * a[2][2] - a[0][2] * a[2][0])
       + b[2] * (a[0][2] * a[1][0] - a[0][0] * a[1][2]);
  /**/
  c[2] = b[0] * (a[1][0] * a[2][1] - a[1][1] * a[2][0])
       + b[1] * (a[0][1] * a[2][0] - a[0][0] * a[2][1])
       + b[2] * (a[0][0] * a[1][1] - a[0][1] * a[1][0]);
  /**/
  for (i = 0; i<3; ++i) b[i] = c[i] / det;
  return det;
}/*GLfloat solve3*/
/**
 @brief Simple sort
*/
void eigsort(
  int n, //!< [in] the number of components
  GLfloat *key, //!< [in] Variables to be sorted [n].
  int *swap //!< [out] Order of index (sorted)
)
{
  int i, j, k;
 
  for (i = 0; i < n; ++i) swap[i] = i;
 
  for (i = 0; i < n - 1; ++i) {
    for (j = i + 1; j < n; ++j) {
      if (key[swap[j]] < key[swap[i]]) {
        /*
         Swap
        */
        k = swap[j];
        swap[j] = swap[i];
        swap[i] = k;
      }/*if (sortee[j][0] < sortee[i][0])*/
    }/*for (j = i + 1; j < n; ++j)*/
  }/*for (i = 0; i < n - 1; ++i)*/
}/*eigsort*/
/**
 @brief Calculate normal vector from corners of triangle
*/
void normal_vec(
  GLfloat in1[3], //!< [in] Corner 1
  GLfloat in2[3], //!< [in] Corner 2
  GLfloat in3[3], //!< [in] Corner 3
  GLfloat out[3] //!< [out] The normal vector
)
{
  int i;
  GLfloat norm;
  out[0] = in1[1] * in2[2] - in1[2] * in2[1]
         + in2[1] * in3[2] - in2[2] * in3[1]
         + in3[1] * in1[2] - in3[2] * in1[1];
  out[1] = in1[2] * in2[0] - in1[0] * in2[2]
         + in2[2] * in3[0] - in2[0] * in3[2]
         + in3[2] * in1[0] - in3[0] * in1[2];
  out[2] = in1[0] * in2[1] - in1[1] * in2[0]
         + in2[0] * in3[1] - in2[1] * in3[0]
         + in3[0] * in1[1] - in3[1] * in1[0];
  norm = sqrtf(out[0] * out[0] + out[1] * out[1] + out[2] * out[2]);
  for (i = 0; i<3; i++) out[i] = out[i] / norm;
} /* normal_vec */
/**
 @brief OpenMP wrapper, get the number of threads
 @return the number of threads 
*/
int get_thread() {
  int ithread;
#if defined(_OPENMP)
  ithread = omp_get_thread_num();
#else
  ithread = 0;
#endif
  return ithread;
}