请问用MATLAB怎么绘制bezier曲线

function

[x,y]=bezier(x,y)

%用法：

%bezier(x,y)

%

生成n-1次贝塞尔曲线，其中x和y是n个点的坐标

%h=bezier(x,y)

%

生成n-1次贝塞尔曲线并返回曲线句柄

%[x,y]=bezier(x,y)

%

返回n-1次贝塞尔曲线的坐标

%例子：

%bezier([5,6,10,12],[0

5

-5

-2])

n=length(x)

t=linspace(0,1)

xx=0yy=0

for

k=0:n-1

tmp=nchoosek(n-1,k)*t.^k.*(1-t).^(n-1-k)

xx=xx+tmp*x(k+1)

yy=yy+tmp*y(k+1)

end

if

nargout==2

x=xxy=yy

end

h=plot(xx,yy)

if

nargout==1

x=h

end

/* Subroutine to generate a Bezier curve.

Copyright (c) 2000 David F. Rogers. All rights reserved.

b[] = array containing the defining polygon vertices

b[1] contains the x-component of the vertex

b[2] contains the y-component of the vertex

b[3] contains the z-component of the vertex

Basis = function to calculate the Bernstein basis value (see MECG Eq 5-65)

cpts = number of points to be calculated on the curve

Fractrl = function to calculate the factorial of a number

j[] = array containing the basis functions for a single value of t

npts = number of defining polygon vertices

p[] = array containing the curve points

p[1] contains the x-component of the point

p[2] contains the y-component of the point

p[3] contains the z-component of the point

t = parameter value 0 <= t <= 1

*/

#include <math.h>

/* function to calculate the factorial */

float factrl(int n)

{

static int ntop=6

static float 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) printf("\nNegative factorial in routine FACTRL\n")

if (n > 32) printf("\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 floating point number */

}

/* function to calculate the factorial function for Bernstein basis */

float Ni(int n,int i)

{

float ni

ni = factrl(n)/(factrl(i)*factrl(n-i))

return ni

}

/* function to calculate the Bernstein basis */

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

{

float basis

float ti /* this is t^i */

float 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

}

/* Bezier curve subroutine */

bezier(npts,b,cpts,p)

int cpts

int npts

float b[]

float p[]

{

int i

int j

int i1

int icount

int jcount

int n

float step

float t

float factrl(int)

float Ni(int,int)

float Basis(int,int,float)

/* calculate the points on the Bezier curve */

icount = 0

t = 0

step = 1.0/((float)(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

}

}

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