bezier.cpp File Reference

---

Detailed Description

Author:

unknown_author

Date:

2003-11-19

Version:

Id

bezier.cpp 8459 2010-03-17 22:02:19Z behrisch

Definition in file bezier.cpp.

#include <config.h>
#include <math.h>
#include <iostream>

Go to the source code of this file.

Functions
SUMOReal	Basis (int n, int i, SUMOReal t)
void	bezier (int npts, SUMOReal b[], int cpts, SUMOReal p[])
SUMOReal	factrl (int n)
SUMOReal	Ni (int n, int i)

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Function Documentation

SUMOReal Basis	(	int	n,
		int	i,
		SUMOReal	t
	)

Definition at line 90 of file bezier.cpp.

References Ni(), and SUMOReal.

Referenced by bezier().

                                       {
    SUMOReal basis;
    SUMOReal ti; /* this is t^i */
    SUMOReal tni; /* this is (1 - t)^i */

    /* handle the special cases to avoid domain problem with pow */

    if (t==0. && i == 0) ti=1.0;
    else ti = pow(t,i);
    if (n==i && t==1.) tni=1.0;
    else tni = pow((1-t),(n-i));
    basis = Ni(n,i)*ti*tni; /* calculate Bernstein basis function */
    return basis;
}

void bezier	(	int	npts,
		SUMOReal	b[],
		int	cpts,
		SUMOReal	p[]
	)

Definition at line 107 of file bezier.cpp.

References Basis(), factrl(), Ni(), and SUMOReal.

Referenced by NBNode::computeInternalLaneShape().

                                                       {
    int i;
    int j;
    int i1;
    int icount;
    int jcount;

    SUMOReal step;
    SUMOReal t;

    SUMOReal factrl(int);
    SUMOReal Ni(int,int);
    SUMOReal Basis(int,int,SUMOReal);

    /*    calculate the points on the Bezier curve */

    icount = 0;
    t = 0;
    step = (SUMOReal) 1.0/(cpts -1);

    for (i1 = 1; i1<=cpts; i1++) { /* main loop */

        if ((1.0 - t) < 5e-6) t = 1.0;

        for (j = 1; j <= 3; j++) { /* generate a point on the curve */
            jcount = j;
            p[icount+j] = 0.;
            for (i = 1; i <= npts; i++) { /* Do x,y,z components */
                p[icount + j] = p[icount + j] + Basis(npts-1,i-1,t)*b[jcount];
                jcount = jcount + 3;
            }
        }

        icount = icount + 3;
        t = t + step;
    }
}

SUMOReal factrl

(

int

n

)

Definition at line 58 of file bezier.cpp.

References SUMOReal.

Referenced by bezier(), and Ni().

                       {
    static int ntop=6;
    static SUMOReal a[33]= {
        1.0,1.0,2.0,6.0,24.0,120.0,720.0
    }
    ; /* fill in the first few values */
    int j1;

    if (n < 0) {
        throw 1;
    } //cout << "\nNegative factorial in routine FACTRL\n" ;
    if (n > 32) {
        throw 1;
    } //cout << "\nFactorial value too large in routine FACTRL\n";

    while (ntop < n) { /* use the precalulated value for n = 0....6 */
        j1 = ntop++;
        a[n]=a[j1]*ntop;
    }
    return a[n]; /* returns the value n! as a SUMORealing point number */
}

SUMOReal Ni	(	int	n,
		int	i
	)

Definition at line 82 of file bezier.cpp.

References factrl(), and SUMOReal.

Referenced by Basis(), and bezier().

                         {
    SUMOReal ni;
    ni = factrl(n)/(factrl(i)*factrl(n-i));
    return ni;
}