www.pudn.com > nurbs++3_0_10.zip > tnlength.C

// The first functions are used to compute the bezierMatrix coefficients
// I'm keeping them here in case I need them.
// but this file is used to test the validity of the length function
// this is bases partly on equation 6.86 from the NURBS book

#include 
#include 
#include 

using namespace PLib ; 

// Generates the bezier matrix coefficients
void bezierMatrix(int deg, PlMatrix_float& Mp){
  int i,j ;
  PlMatrix_float bin(deg+1,deg+1) ;

  binomialCoef(bin) ;
  Mp.resize(deg+1,deg+1) ;

  for(i=0;i of degree 2.\n" ;
  float l;
  for(i=0;i<500;++i)
    l = circle.length() ;
  cout << "it's length is " << l << "\terror = " << absolute(2*M_PI-l) << endl ; 

  cout << "Now we use a degree 3 circle to make sure it's still valid\n" ;
  circle.degreeElevate(1) ;
  for(i=0;i<500;++i)
    l = circle.length() ;
  cout << "it's length is " << l << "\terror = " << absolute(2*M_PI-l) << endl ; 

  cout << "\nIn case you forgot, the value should be 2*PI\n" ; 


  cout << "\nNow we test if we can find the length of the curve for a\n"
    "range of the circle: [0.25,0.75].\n" ;
  for(i=0;i<500;++i)
    l = circle.lengthIn(0.25,0.75) ;
  cout << "The length is " << l << "\terror = " << absolute(M_PI-l) << endl ; 

  return 0 ;
}