Isis 3.0 Application Source Code Reference

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circle2.cpp

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#include "Isis.h"
#include "ProcessByLine.h"
#include "SpecialPixel.h"
#include "iException.h"

using namespace std; 
using namespace Isis;

void circle (Buffer &in, Buffer &out);
double cline,csamp,radius;  // Global variables

void IsisMain() {
  // We will be processing by line
  ProcessByLine p;

  // Setup the input and output cubes
  p.SetInputCube("FROM");
  p.SetOutputCube ("TO");
  
  // Get the three points along the edge of the circle
  UserInterface &ui = Application::GetUserInterface();
  double y1 = ui.GetDouble ("LINE1");
  double y2 = ui.GetDouble ("LINE2");
  double y3 = ui.GetDouble ("LINE3");
  double x1 = ui.GetDouble ("SAMP1");
  double x2 = ui.GetDouble ("SAMP2");
  double x3 = ui.GetDouble ("SAMP3");
  
  // Compute the center line/samp and radius of the circle
  double x21 = x2 - x1;
  double y21 = y2 - y1;
  double x31 = x3 - x1;
  double y31 = y3 - y1;
  double den = 2.0 * (x21*y31 - x31*y21);
  if (den == 0.0) {
    string message = "The three points lie on a line so a circle can not be computed";
    throw iException::Message(iException::User,message,_FILEINFO_);
  }

  double sq2 = x21*x21 + y21*y21;
  double sq3 = x31*x31 + y31*y31;
  csamp = (sq2*y31 - sq3*y21) / den;
  cline = (sq3*x21 - sq2*x31) / den;
  
  radius = sqrt(csamp*csamp + cline*cline);
  csamp += x1;
  cline += y1;

  // Start the processing
  p.StartProcess(circle);
  p.EndProcess();
}

// Line processing routine
void circle (Buffer &in, Buffer &out) {
  // Compute part of the distance (doesn't vary since the line is constant)
  double dist, partA, partB;
  partA = cline - (double) in.Line();
  partA *= partA; 

  // Loop for each pixel in the line. 
  for (int i=0; i<in.size(); i++) {
    // Compute the rest of the distance
    partB = csamp - (double) in.Sample(i);
    partB *= partB;
    dist = partA + partB;
    if (dist < 0.0) dist = 0.0; // Shouldn't happen
    dist = sqrt(dist);

    // Mask everything outside the radius and keep what is inside
    if (dist <= radius) {
      out[i] = in[i];
    }
    else {
      out[i] = NULL8;
    }
  }
}