Notes

#include<GL/glut.h>
#include<stdio.h>
#include<math.h>
#define PI 3.1416
typedef struct point
{
GLfloat x, y, z;
};
void bino(int n, int *C)
{
int k, j;
for(k=0; k<=n; k++)
{
C[k]=1;
for(j=n; j>=k+1; j--)
C[k]*=j;
for(j=n-k; j>=2; j--)
C[k]/=j;
}
}
void computeBezPt(float u, point *pt1, int cPt, point *pt2, int *C)
{
int k, n=cPt-1;
float bFcn;
pt1 ->x =pt1 ->y = pt1->z=0.0;
for(k=0; k< cPt; k++)
{
bFcn = C[k] * pow(u, k) * pow( 1-u, n-k);
pt1 ->x += pt2[k].x * bFcn;
pt1 ->y += pt2[k].y * bFcn;
pt1 ->z += pt2[k].z * bFcn;
}
}
void bezier(point *pt1, int cPt, int bPt)
{
point bcPt;
float u;
int *C, k;
C= new int[cPt];
bino(cPt-1, C);
glBegin(GL_LINE_STRIP);
for(k=0; k<=bPt; k++)
{
u=float(k)/float(bPt);
computeBezPt(u, &bcPt, cPt, pt1, C);
glVertex2f(bcPt.x, bcPt.y);
}
glEnd();
delete[]C;
}
float theta = 0;
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
int nCtrlPts = 4, nBCPts =20;
point ctrlPts[4] = {{100, 400, 0}, {150, 450, 0}, {250, 350, 0},
{300, 400, 0}
};
ctrlPts[1].x +=50*sin(theta * PI/180.0);
ctrlPts[1].y +=25*sin(theta * PI/180.0);
ctrlPts[2].x -= 50*sin((theta+30) * PI/180.0);
ctrlPts[2].y -= 50*sin((theta+30) * PI/180.0);
ctrlPts[3].x -= 25*sin((theta) * PI/180.0);
ctrlPts[3].y += sin((theta-30) * PI/180.0);
theta+=0.2;
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glPointSize(5);
glPushMatrix();
glLineWidth(5);
glColor3f(1, 0.4, 0.2); //Indian flag: Orange color code
for(int i=0; i<50; i++)
{
glTranslatef(0, -0.8, 0);
bezier(ctrlPts, nCtrlPts, nBCPts);
}
glColor3f(1, 1, 1); //Indian flag: white color code
for(int i=0; i<50; i++)
{
glTranslatef(0, -0.8, 0);
bezier(ctrlPts, nCtrlPts, nBCPts);
}
glColor3f(0, 1, 0); //Indian flag: green color code
for(int i=0; i<50; i++)
{
glTranslatef(0, -0.8, 0);
bezier(ctrlPts, nCtrlPts, nBCPts);
}
glPopMatrix();
glColor3f(0.7, 0.5,0.3);
glLineWidth(5);
glBegin(GL_LINES);
glVertex2f(100,400);
glVertex2f(100,40);
glEnd();
glutPostRedisplay();
glutSwapBuffers();
}
void init()
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0,500,0,500);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowPosition(0, 0);
glutInitWindowSize(500,500);
glutCreateWindow("Bezier Curve");
init();
glutDisplayFunc(display);
glutMainLoop();
}