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sxy_utils.cpp

Go to the documentation of this file.

/* ------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------- */
/* ------------------------------------------------------------------------- */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <ctype.h>
#include <math.h>
#include <float.h>

#include <cd.h>

#include "sxy_utils.h"

#define min(a,b) ( ((a)<(b)) ? (a) : (b) )
#define max(a,b) ( ((a)>(b)) ? (a) : (b) )

/* ------------------------------------------------------------------------- */

/* ------------------------------------------------------------------------- */

/* ......................................................................... */
double SXYUtil::makeInterpolation( double x1, double y1, 
    double x2, double y2, double x ) {
    return ((((x-x1)*(y2-y1))/(x2-x1))+y1);
}

/* ......................................................................... */
void SXYUtil::calcZoomOut(double &xmin, double &xmax) {
   double dx = (xmax - xmin) / 10.0;
   xmin -= dx; xmax += dx;
}

/* ......................................................................... */

void SXYUtil::assertValues(double &min, double &max) {
  if (min == FLT_MAX) {
    if (max == -FLT_MAX) {
        max = 1000;
        min = 0;
    }
    else min = max - 10;
  }
  if (max == -FLT_MAX) max = min + 10;
}

/* ......................................................................... */
void SXYUtil::calcMinMax(double &xmin, double &xmax, 
double &ymin, double &ymax) {
  
  SXYUtil::assertValues(xmin, xmax);
  SXYUtil::assertValues(ymin, ymax);

  if (xmin >= xmax) {
      double tmp = xmin;
      xmin = xmax - 10;
      xmax = tmp + 10;
  }
  if (ymin >= ymax) {
      double tmp = ymin;
      ymin = ymax - 10;
      ymax = tmp + 10;
  }
}

/* ......................................................................... */
int SXYUtil::calcPrecision(double min, double max) {
  double diff = fabs(max - min);
  assert (diff >= 0);
  if (diff > 100) return 0;
  else return -((int)log10(diff)) + 2;
}

/* ......................................................................... */
int SXYUtil::intersectPoints( int is_log_x, int is_log_y,
double ax1, double ay1, double ax2, double ay2,
double bx1, double by1, double bx2, double by2,
double& ix, double& iy ) {

  if (is_log_x) {
     if ( (ax1<1e-15) || (ax2<1e-15) || (bx1<1e-15) || (bx2<1e-15) ) return 0;
     ax1 = log10(ax1); ax2 = log10(ax2);
     bx1 = log10(bx1); bx2 = log10(bx2);
  }

  if (is_log_y) {
     if ( (ay1<1e-15) || (ay2<1e-15) || (by1<1e-15) || (by2<1e-15) ) return 0;
     ay1 = log10(ay1); ay2 = log10(ay2);
     by1 = log10(by1); by2 = log10(by2);
  }

  // Cálculo dos coeficientes (alfa e beta) dos segmentos A e B 
  double dy_a = ay2-ay1;
  double dy_b = by2-by1;
  double dx_a = ax2-ax1;
  double dx_b = bx2-bx1;

  // Retas verticais e paralelas
  int va = fabs(dx_a) < 1e-5;
  int vb = fabs(dx_b) < 1e-5;
  if (va && vb) return 0;

  if (va) {
     ix = ax1;
     iy = SXYUtil::makeInterpolation(bx1,by1,bx2,by2,ix);
  }
  else if (vb) {
     ix = bx1;
     iy = SXYUtil::makeInterpolation(ax1,ay1,ax2,ay2,ix);
  }
  else {
     double alfa_a = dy_a / dx_a;
     double alfa_b = dy_b / dx_b;
     double beta_a = ay1 - alfa_a*ax1;
     double beta_b = by1 - alfa_b*bx1;

     // Teste de retas paralelas
     if ( fabs(alfa_a - alfa_b) < 1e-5 ) return 0;

     ix = (-beta_a + beta_b) / (alfa_a - alfa_b);
     iy = alfa_a * ix + beta_a;
  }

  ix = is_log_x ? pow(10,ix) : ix;
  iy = is_log_y ? pow(10,iy) : iy;

  if (is_log_x) {
     ax1 = pow(10,ax1); ax2 = pow(10,ax2);
     bx1 = pow(10,bx1); bx2 = pow(10,bx2);
  }

  if (is_log_y) {
     ay1 = pow(10,ay1); ay2 = pow(10,ay2);
     by1 = pow(10,by1); by2 = pow(10,by2);
  }

  double laminx = min(ax1,ax2);
  double laminy = min(ay1,ay2);
  double lamaxx = max(ax1,ax2);
  double lamaxy = max(ay1,ay2);
  if ( ix<laminx || ix>lamaxx || iy<laminy || iy>lamaxy ) return 0;

  double lbminx = min(bx1,bx2);
  double lbminy = min(by1,by2);
  double lbmaxx = max(bx1,bx2);
  double lbmaxy = max(by1,by2);
  if ( ix<lbminx || ix>lbmaxx || iy<lbminy || iy>lbmaxy ) return 0;

  return 1;
}

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SXY
Tecgraf / PUC-Rio - Computer Graphics Technology Group