// Computer Graphics - Amir Hesami
// This program shows the effect of the reshape function.
// The result is the aspect ratio of the object will be changed. 
// reshape2.cpp

#include <GL/glut.h>

#pragma comment(lib, "opengl32.lib")  // Link OpenGL32.lib
#pragma comment(lib, "glu32.lib")	  // Link Glu32.lib
#pragma comment(lib, "glut32.lib")    // Link Glut32.lib
#pragma comment(linker, "/entry:\"mainCRTStartup\"" )  // set the entry point to be main()
#pragma comment(linker, "/subsystem:\"Windows\"" )  // set the entry point to be main()


void display();

void init();
void reshape(GLsizei , GLsizei );
int wh,ww;// for further use.
int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500,500);
	glutInitWindowPosition(100,100);
	glutCreateWindow("The effect of reshape");
	glutDisplayFunc(display);
	glutReshapeFunc(reshape);
	init();
	glutMainLoop();
	return 0;
}

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

	//Set the drawing color to red
	glColor3f(1.0,0.0,0.0);

	//draw unit square polygon
	glBegin(GL_POLYGON);
	   glVertex2f(-0.5,-0.5);
	   glVertex2f(-0.5,0.5);
	   glVertex2f(0.5,0.5);
	   glVertex2f(0.5,-0.5);
    glEnd();

	//Flush the buffer
	glFlush();
}

void init()
{
	//Set the background color
	glClearColor(1.0,1.0,1.0,1.0);
    
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(-1.0,1.0,-1.0,1.0);
}

void reshape(GLsizei w, GLsizei h)
{
	//adjust clipping box

    glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

    gluOrtho2D(-2.0,2.0,-2.0,2.0);
	
	glMatrixMode(GL_MODELVIEW);
    //adjust the viewport
	glViewport(0,0,w,h);
	//set global size for use by drawing routine

	ww = w;
	wh = h;
}