贝塞尔曲线的生成(可调整控制点)

// homework3_1.cpp : Defines the entry point for the console application.

//

#include \"stdafx.h\"

#include

#include

#include

#include

#include

#include

#include

int wide,height;

int lefthit=0;

float x[4]={25,100,150,250},y[4]={25,125,175,50};

void reshape(int w, int h)

{

wide = w;

height = h;

glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

gluOrtho2D(-w/2,w/2,-h/2,h/2);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

}

int zuhe(int n,int k)

{

int i,s1,s2;

s1=1;

s2=1;

if(k==0) return 1;

for(i=n;i>=n-k+1;i--) s1=s1*i;

for(i=k;i>=2;i--) s2=s2*i;

return s1/s2;

}

float fang(float n,int k)

{

if(k==0) return 1;

return pow(n,k);

}

float benkn(int n,int k,float t)

{

return zuhe(n,k)*fang(t,k)*fang(1-t,n-k);

}

void Init(void)

{

glClearColor(1.0,1.0,1.0,0.0);

}

void display(void)

{

glClear(GL_COLOR_BUFFER_BIT);

glPointSize(8.0);

glColor3f(1.0f,0.0f,0.0f);

float x1[11],y1[11],t[11]={0},s=0.0;

int i;

for(i=1;i<11;i++) {s=s+0.1;t[i]=s;}

for(i=0;i<11;i++)

{

x1[i]=x[0]*benkn(3,0,t[i])+x[1]*benkn(3,1,t[i])+x[2]*benkn(3,2,t[i])+x[3]*benkn(3,3,t[i]);

y1[i]=y[0]*benkn(3,0,t[i])+y[1]*benkn(3,1,t[i])+y[2]*benkn(3,2,t[i])+y[3]*benkn(3,3,t[i]);

}

glBegin(GL_POINTS);

glVertex2f(x[0],y[0]);

glVertex2f(x[1],y[1]);

glVertex2f(x[2],y[2]);

glVertex2f(x[3],y[3]);

glEnd();

glBegin(GL_LINE_STRIP);

for(i=0;i<11;i++)

glVertex2f(x1[i],y1[i]);

glEnd();

glFlush();

}

void mouse(int key,int state,int m,int n)

{

if (lefthit==0) glClear(GL_COLOR_BUFFER_BIT);

int i=0;

glColor3f(1.0f,0.0f,0.0f);

if (key==GLUT_LEFT_BUTTON&&state == GLUT_DOWN)

{

glBegin(GL_POINTS);

for(i=lefthit;i<=3;i++)

{

x[i]=(m-wide/2);

y[i]=(height/2-n);

glVertex2f(x[i],y[i]);

printf(\"%f %f\\n\

}

glEnd();

glFlush();

lefthit++;

if (lefthit>=4)

{

display();

lefthit=0;

}

}

}

void main(int argc,char** argv)

{

glutInit(&argc,argv);

glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);

glutInitWindowSize(640,480);

glutInitWindowPosition(100,150);

glutCreateWindow(\"贝塞尔曲线\");

glutReshapeFunc(reshape);

glutDisplayFunc(display);

glutMouseFunc(mouse);

Init();

glutMainLoop();

}