bresenham.cpp

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/*
 * Copyright (c) 2010, Maxim Likhachev
 * 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 the University of Pennsylvania 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.
 */
#include <sbpl_interface/bresenham.h>

void get_bresenham3d_parameters(int p1x, int p1y, int p1z, int p2x, int p2y, int p2z, bresenham3d_param_t *params)
{
  params->X1=p1x;
  params->Y1=p1y;
  params->Z1=p1z;
  params->X2=p2x;
  params->Y2=p2y;
  params->Z2=p2z;

  params->XIndex = params->X1;
  params->YIndex = params->Y1;
  params->ZIndex = params->Z1;

  params->dx = fabs((double)(p2x-p1x));
  params->dy = fabs((double)(p2y-p1y));
  params->dz = fabs((double)(p2z-p1z));
  params->dx2 = params->dx << 1;
  params->dy2 = params->dy << 1;
  params->dz2 = params->dz << 1;

  //get direction of slope
  if((double)(p2x-p1x) < 0)
    params->IncX = -1;
  else
    params->IncX = 1;

  if((double)(p2y-p1y) < 0)
    params->IncY = -1;
  else
    params->IncY = 1;

  if((double)(p2z-p1z) < 0)
    params->IncZ = -1;
  else
    params->IncZ = 1;

  //choose which axis to use as the index
  if(params->dx >= params->dy && params->dx >= params->dz)
  {
    params->UsingXYZIndex = 0;
    params->err1 = params->dy2 - params->dx;
    params->err2 = params->dz2 - params->dx;
  }
  else if(params->dy >= params->dx && params->dy >= params->dz)
  {
    params->UsingXYZIndex = 1;
    params->err1 = params->dx2 - params->dy;
    params->err2 = params->dz2 - params->dy;
  }
  else
  {
    params->UsingXYZIndex = 2;
    params->err1 = params->dy2 - params->dz;
    params->err2 = params->dx2 - params->dz;
  }
}

void get_current_point3d(bresenham3d_param_t *params, int *x, int *y, int *z)
{
  *x = params->XIndex;
  *y = params->YIndex;
  *z = params->ZIndex;
}

int get_next_point3d(bresenham3d_param_t *params)
{
  //check to see if at end of line
  if (params->XIndex == params->X2 && params->YIndex == params->Y2 && params->ZIndex == params->Z2)
    return 0;

  if (params->UsingXYZIndex == 0)
  {
    if (params->err1 > 0) {
      params->YIndex += params->IncY;
      params->err1 -= params->dx2;
    }
    if (params->err2 > 0) {
      params->ZIndex += params->IncZ;
      params->err2 -= params->dx2;
    }
    params->err1 += params->dy2;
    params->err2 += params->dz2;
    params->XIndex += params->IncX;
  }
  else if(params->UsingXYZIndex == 1)
  {
    if (params->err1 > 0) {
      params->XIndex += params->IncX;
      params->err1 -= params->dy2;
    }
    if (params->err2 > 0) {
      params->ZIndex += params->IncZ;
      params->err2 -= params->dy2;
    }
    params->err1 += params->dx2;
    params->err2 += params->dz2;
    params->YIndex += params->IncY;
  }
  else
  {
    if (params->err1 > 0) {
      params->YIndex += params->IncY;
      params->err1 -= params->dz2;
    }
    if (params->err2 > 0) {
      params->XIndex += params->IncX;
      params->err2 -= params->dz2;
    }
    params->err1 += params->dy2;
    params->err2 += params->dx2;
    params->ZIndex += params->IncZ;
  }
  return 1;
}