WAP to draw square in Opengl.

#include <GL\glut.h>

void init(void)
{
glClearColor(1.0, 1.0, 1.0, 0.0); // Set display window colour to white

glMatrixMode(GL_PROJECTION); // Set projection parameters
gluOrtho2D(0.0, 200.0, 0.0, 150.0);
}

void lineSegment(void)
{
glClear(GL_COLOR_BUFFER_BIT); // Clear display window

glColor3f(1.0, 0.0, 0.0); //Set line colour to red

glBegin(GL_LINES); //Specify line segment geometry
glVertex2i(10,10 );
glVertex2i(10,50);
glVertex2i(10,50);
glVertex2i(50,50);
glVertex2i(50,50);
glVertex2i(50,10);
glVertex2i(50,10);
glVertex2i(10,10);
glEnd();

glFlush(); // Process all OpenGL routines

}

int main(int argc, char* argv[])
{
glutInit(&argc, argv); // Initalise GLUT
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB); // Set display mode

glutInitWindowPosition(50, 100); // Set window position
glutInitWindowSize(400, 300); // Set window size
glutCreateWindow("An Example OpenGL Program"); // Create display window

init(); // Execute initialisation procedure
glutDisplayFunc(lineSegment); // Send graphics to display window
glutMainLoop(); // Display everything and wait

return 0;
}