Bezier曲线

  1 #include <windows.h>    
  2 #include <math.h>    
  3 #include <gl/GL.h>    
  4 #include <gl/glut.h>    
  5 int SCREEN_HEIGHT = 480;    
  6 int NUMPOINTS = 0;    
  7 class Point    
  8 {    
  9 public:    
 10     float x, y;    
 11     void setxy(float x2, float y2)    
 12     {    
 13         x = x2;    
 14         y = y2;    
 15     }    
 16     Point  operator&(const Point & rPoint)    
 17     {    
 18         x = rPoint.x;    
 19         y = rPoint.y;    
 20         return * this;    
 21     }    
 22 };    
 23 Point abc[4];    
 24 void myInit()    
 25 {    
 26     glClearColor(0.0,0.0,0.0,0.0);    
 27     glColor3f(1.0f, 0.0, 0.0);    
 28     glPointSize(4.0);    
 29     glMatrixMode(GL_PROJECTION);    
 30     glLoadIdentity();    
 31     gluOrtho2D(0.0, 640, 0.0, 480.0);    
 32 }    
 33 void drawDot(Point pt)     
 34 {    
 35     glBegin(GL_POINTS);    
 36     glVertex2f(pt.x, pt.y);    
 37     glEnd();    
 38     glFlush();    
 39 }    
 40 void drawLine(Point p1, Point p2)    
 41 {    
 42     glBegin(GL_LINES);    
 43     glVertex2f(p1.x, p1.y);    
 44     glVertex2f(p2.x, p2.y);    
 45     glEnd();    
 46     glFlush();    
 47 }    
 48 //四个控制点的贝塞尔曲线 即三次Bezier曲线  
 49 Point drawBezier(Point A, Point B, Point C, Point D,double t)     
 50 {    
 51     Point P;  
 52     double a1 = pow((1-t),3);  
 53     double a2 = pow((1-t),2)*3*t;  
 54     double a3 = 3*t*t*(1-t);  
 55     double a4 = t*t*t;  
 56   
 57     P.x = a1*A.x+a2*B.x+a3*C.x+a4*D.x;  
 58     P.y = a1*A.y+a2*B.y+a3*C.y+a4*D.y;  
 59     return P;    
 60 }    
 61 void myMouse(int button, int state, int x, int y)    
 62 {    
 63     if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)    
 64     {    
 65         abc[NUMPOINTS].setxy((float)x, (float)(SCREEN_HEIGHT - y));    
 66         NUMPOINTS++;    
 67         if (NUMPOINTS == 4)    
 68         {    
 69             glColor3f(1.0, 0.0, 1.0);    
 70             drawDot(abc[0]);    
 71             drawDot(abc[1]);    
 72             drawDot(abc[2]);    
 73             drawDot(abc[3]);    
 74             glColor3f(1.0, 1.0, 0.0);    
 75             drawLine(abc[0], abc[1]);    
 76             drawLine(abc[1], abc[2]);    
 77             drawLine(abc[2], abc[3]);    
 78             glColor3f(0.0, 1.0, 1.0);    
 79             Point POld = abc[0];    
 80             for (double t = 0.0; t<=1.0;t+=0.1)    
 81             {    
 82                 Point P = drawBezier(abc[0], abc[1], abc[2],  abc[3], t);    
 83                 drawLine(POld, P);    
 84                 POld = P;    
 85             }    
 86             glColor3f(1.0, 0.0, 0.0);    
 87             NUMPOINTS = 0;    
 88         }    
 89     }    
 90 }    
 91 void myDisplay()    
 92 {    
 93     glClear(GL_COLOR_BUFFER_BIT);    
 94     glFlush();    
 95 }    
 96 int main(int argc, char * agrv[])    
 97 {    
 98     glutInit(&argc, agrv);    
 99     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);    
100     glutInitWindowSize(640, 480);    
101     glutInitWindowPosition(100, 150);    
102     glutCreateWindow("Bezier Curve");    
103     glutMouseFunc(myMouse);    
104     glutDisplayFunc(myDisplay);    
105     myInit();    
106     glutMainLoop();    
107     return 0;    
108 }
保留代码自己慢慢看~