10. Write a program to create (without using built in function) a square by implementing shear algorithm along 1. X-axis, 2.Y-axis

#include<stdio.h>
#include <GL/glut.h>
#include<math.h>
void init();
void display();
void drawPolygon(int, int, int, int, int, int, int, int);
void setPixel(GLint, GLint);
void main(int argc, char**argv)
{
glutInit(&argc,argv); //initialize GLUT
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //initialize display mode
glutInitWindowSize(300,300); //set display-window width & height
glutInitWindowPosition(600,50); //set display-window upper-left position
glutCreateWindow("Implementation of Shear Algorithm");
init(); //initialze OpenGL
glutDisplayFunc(display); //call graphics to be displayed on the window
glutMainLoop(); //display everything and wait
}
void init(void)
{
glClearColor(1.0,1.0,1.0,0.0); //set display-window background color to white
glMatrixMode(GL_PROJECTION); //set projection paramaters
gluOrtho2D(0.0,300.0,0.0,300.0);
}
void setPixel(GLint xCoordinate, GLint yCoordinate)
{
glBegin(GL_POINTS);
glVertex2i(xCoordinate,yCoordinate);
glEnd();
glFlush(); //executes all OpenGL functions as quickly as possible
}
void drawPolygon(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4)
{
glColor3f(0.0, 0.0, 0.0);
glBegin(GL_LINES);
glVertex2i(x1, y1);
glVertex2i(x2, y2);
glEnd();
glBegin(GL_LINES);
glVertex2i(x2, y2);
glVertex2i(x3, y3);
glEnd();
glBegin(GL_LINES);
glVertex2i(x3, y3);
glVertex2i(x4, y4);
glEnd();
glBegin(GL_LINES);
glVertex2i(x4, y4);
glVertex2i(x1, y1);
glEnd();
glFlush();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);
glPointSize(2.0);
GLint x0=100; // setting the starting point of square
GLint y0=100;
GLint x1 = 150; //setting the third point of square
GLint y1 = 150;
drawPolygon(x0, y0, x1, y0, x1, y1, x0, y1); //draw square
int opt;
float sh;
GLint x0_New, x1_New, y0_New, y1_New ;
for(;;)
{
printf(" \n 1. Shear along X-axis \n 2. Shear along Y-axis \n 3. Exit\n");
printf("Enter your option:");
scanf("%d", & opt);
switch(opt)
{
case 1: printf("\nEnter shear parameter: ");
scanf("%f", &sh);
x0_New = x0+ sh * y1;
x1_New = x1+ sh * y1;
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);
glPointSize(2.0);
drawPolygon(x0, y0, x1, y0, x1_New, y1, x0_New, y1);
break;
case 2:
printf("\nEnter shear parameter: ");
scanf("%f", &sh);
y0_New = y0+ sh * y1;
y1_New = y1+ sh * y1;
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0,0.0,0.0);
glPointSize(2.0);
drawPolygon(x0, y0, x1, y0_New, x1, y1_New, x0, y1);
break;
default: exit(0);
}
}
}