bresenham.cpp

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/* Author: Benjamin Cohen */

#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;
}