# 8. COMPUTER GRAPHICS LAB | READ NOW

VTU COMPUTER GRAPHICS LAB

Program 8:- Develop a menu driven program to animate a flag using Bezier Curve algorithm

## STEPS TO RUN CG PROGRAM

1. Copy the below copy
2. Past it in any code compiler ex- Code Blocks, DEV C++, VS Code
3. Save the file with .cpp extension
4. Compile and Run the code
5. Program Execution Successful

Note:- if you use Dev C++, right click on project>project options>parameter>linker paste the below code in Linker – as shown in image.

```-lopengl32
-lfreeglut
-lglu32```

## Program Code [lab8.cpp]

```#include<GL/glut.h>
#include<math.h>
#include<stdio.h>

void bezierCoefficients(int n,int *c)
{
int k,i;
for(k=0;k<=n;k++)
{
c[k]=1;
for(i=n;i>=k+1;i--)
c[k]*=i;
for(i=n-k;i>=2;i--)
c[k]/=i;
}
}

void display()
{
int cp[4][2]={{10,10},{100,200},{200,50},{300,300}};
int c[4],k,n=3;
float x,y,u,blend;
bezierCoefficients(n,c);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);
glLineWidth(5.0);
glBegin(GL_LINE_STRIP);
for(u=0;u<1.0;u+=0.01)
{
x=0;y=0;
for(k=0;k<4;k++)
{
blend=c[k]*pow(u,k)*pow(1-u,n-k);
x+=cp[k][0]*blend;
y+=cp[k][1]*blend;
}
glVertex2f(x,y);
}
glEnd();
glFlush();
}

void myinit()
{
glClearColor(1.0,1.0,1.0,1.0);
glColor3f(1.0,0.0,0.0);
glPointSize(5.0);
gluOrtho2D(0.0,600,0.0,600.0);
}

int main(int argc, char ** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowSize(600,600);
glutCreateWindow("Bezier Curve");
glutDisplayFunc(display);
myinit();
glutMainLoop();
return 0;
}```

## Alternative Method [lab8.cpp]

```#include<GL/glut.h>
#include<math.h>
#include<stdio.h>

void bezierCoefficients(int n,int *c)
{
int k,i;
for(k=0;k<=n;k++)
{
c[k]=1;
for(i=n;i>=k+1;i--)
c[k]*=i;
for(i=n-k;i>=2;i--)
c[k]/=i;
}
}

void display()
{
int cp[4][2]={{10,10},{100,200},{200,50},{300,300}};
int c[4],k,n=3;
float x,y,u,blend;
bezierCoefficients(n,c);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);
glLineWidth(5.0);
glBegin(GL_LINE_STRIP);
for(u=0;u<1.0;u+=0.01)
{
x=0;y=0;
for(k=0;k<4;k++)
{
blend=c[k]*pow(u,k)*pow(1-u,n-k);
x+=cp[k][0]*blend;
y+=cp[k][1]*blend;
}
glVertex2f(x,y);
}
glEnd();
glFlush();
}

void myinit()
{
glClearColor(1.0,1.0,1.0,1.0);
glColor3f(1.0,0.0,0.0);
glPointSize(5.0);
gluOrtho2D(0.0,600,0.0,600.0);
}

int main(int argc, char ** argv)
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowSize(600,600);
glutCreateWindow("Bezier Curve");
glutDisplayFunc(display);
myinit();
glutMainLoop();
return 0;
}```