Draw the letters S, P, R or U of English alphabet using multiple Bézier curves. 

A complete code for plotting Bezier curves is given previously. There in the code, control points for the Bézier curves are taken using mouse input.  Plot Bézier curves by first identifying the control points of the curve and then storing them in an array.  Always employ curves of same degree for plotting different parts of the alphabet letter.  In the following code, character  P  is generated using only quadratic Bézier curves. Straight line segments are also generated using a quadratic Bézier curve by choosing the control points on a straight line. 

/* Create the character P using multiple Bezier curves*/

#include

#include

#include  

#define n 2 //Uniform degree of all Bezier curves 

int ww=640,wh = 480; //Window Size

int OUT_CURVES = 18; //Counter for curves in outer boundary

int IN_CURVES=12; // Counter for curves in inner boundary

//Coordinates of control points for outer curves

int Px_Out[21]={90, 120, 160, 180, 180, 180, 180, 180, 160,

140, 120, 120,120, 120, 140, 140,140, 120, 90, 90, 90};

int Py_Out[21]={100, 100, 100, 100, 120, 140, 160, 180, 180,

180, 180, 230,230,240,240, 250, 260, 260, 260, 200,100};

//Coordinates of control points for inner curves

int Px_In[15]={120, 130, 140, 160, 160, 160, 160,

160,160,160,130,120,120,120,120};

int Py_In[15]={120, 120, 120, 120, 130, 140,

140,145,150,160,160,160,160,130,120};  

void myInit(){

    glClearColor(0.0,0.0,0.0,0.0);

    glColor3f(0.0,1.0,0.0);

    glPointSize(4.0); //Select point size 

    gluOrtho2D(0.0,640.0,0.0,480.0); 

    //For setting the clipping areas  

} //Initialize    

//Point plotting    

//Computing factorial of a number k

int factorial(int k) {

 int fact=1,i;

 for(i=1;i<=k;i++)

 fact=fact*i;

 return fact; }  

/* Draw a bezier curve with control points (x[i],y[i]),

i=0,..., n */

void drawBezier(int x[n+1], int y[n+1]) {

 double P_x,P_y;

 glColor3f(1.0,1.0,1.0); //Set drawing colour for curve

 for( double t=0.0;t<=1.0;t+=0.01){

  P_x=0.0; 

  P_y=0.0;

 glBegin(GL_POINTS); //Draw point (P_x,P_y) on the curve 

for( int i=0;i<=n;i++) {

 int cni=factorial(n)/(factorial(n-i)*factorial(i));

 P_x = P_x+(double)(x[i]*cni)*pow(1 - t,n-i)*pow(t,i); 

 P_y = P_y+(double)(y[i]*cni)*pow(1 - t,n-i)*pow(t,i); 

   }

   glVertex2f(P_x,wh -P_y); 

   }

 glEnd();

glFlush(); }

//Draw character P using Bezier curves

void Bezier()

{

 int Control_x[3], Control_y[3];

 //Outer Boundary curves 

 for (int j=0;j<=OUT_CURVES; j+=2){

  Control_x[0]=Px_Out[j];

  Control_y[0]=Py_Out[j];

  Control_x[1]=Px_Out[j+1];

  Control_y[1]=Py_Out[j+1];

  Control_x[2]=Px_Out[j+2];

  Control_y[2]=Py_Out[j+2];

 drawBezier(Control_x, Control_y);

 }

 //Inner Boundary curves

 for (int j=0;j<=IN_CURVES; j+=2){

  Control_x[0]=Px_In[j];

  Control_y[0]=Py_In[j];

  Control_x[1]=Px_In[j+1];

  Control_y[1]=Py_In[j+1];

  Control_x[2]=Px_In[j+2];

  Control_y[2]=Py_In[j+2];

 drawBezier(Control_x, Control_y);

 }

 glFlush();

}

//Draw character P on a mouse click

void myMouse(int button, int state, int x, int y) { 

 if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {      

  Bezier();

  glFlush();} 

}

void myDisplay() {

    glClear(GL_COLOR_BUFFER_BIT);

 //Bezier();

    glFlush();

}

int main() {

    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);

    glutInitWindowSize(ww,wh);

    glutInitWindowPosition(200,200);

    glutCreateWindow("Bezier curves");

    glutMouseFunc(myMouse);

    glutDisplayFunc(myDisplay);

    myInit();

    glutMainLoop();

 return 0;

}

 Other characters R,S,U can be similarly plotted using appropriate coordinates of the control points.