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

void ejesCoordenada() {
	
	glLineWidth(2.5);
	glBegin(GL_LINES);
		glColor3f(1.0,0.0,0.0);
		glVertex2f(0,10);
		glVertex2f(0,-10);
		glColor3f(0.0,0.0,1.0);
		glVertex2f(10,0);
		glVertex2f(-10,0);
	glEnd();

	glLineWidth(1.5);
	int i;
	glColor3f(0.0,1.0,0.0);
	glBegin(GL_LINES);
		for(i = -10; i <=10; i++){
			if (i!=0) {		
				if ((i%2)==0){	
					glVertex2f(i,0.4);
					glVertex2f(i,-0.4);

					glVertex2f(0.4,i);
					glVertex2f(-0.4,i);
				}else{
					glVertex2f(i,0.2);
					glVertex2f(i,-0.2);

					glVertex2f(0.2,i);
					glVertex2f(-0.2,i);

				}
			}
		}
		
	glEnd();

	glLineWidth(1.0);
}

void dibujarCuadrado() {

	glBegin(GL_LINE_LOOP);
		glVertex2f(-1,1);
		glVertex2f(1,1);
		glVertex2f(1,-1);
		glVertex2f(-1,-1);
	glEnd();

}

void dibujarTriangulo() {

	glBegin(GL_LINE_LOOP);
		glVertex2f(0,0);
		glVertex2f(0,1);
		glVertex2f(-1,0);
	glEnd();

	glBegin(GL_LINE_LOOP);
		glVertex2f(0,0);
		glVertex2f(0,-1);
		glVertex2f(1,0);
	glEnd();


}

void display(){

	glClearColor(0.0f, 0.0f, 0.0f ,1.0f);				
	glClear(GL_COLOR_BUFFER_BIT);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
	ejesCoordenada();

	
	glColor3f(1.0,1.0,0.0);


	glTranslatef(2.0,1.0,0.0);	
	dibujarCuadrado();
	

	glColor3f(1.0,0.5,0.5);


	glTranslatef(3.0,0.0,0.0);
	glScalef(2.0,2.0,2.0);
	dibujarTriangulo();

	glFlush();

}

void cambioventana(int w, int h){

	float aspectratio;

	if (h==0)
		h=1;

	glViewport(0, 0, w, h);

    	glMatrixMode(GL_PROJECTION);

    	glLoadIdentity();


	aspectratio = (float) w / (float) h;

	if (w<=h) {

		glOrtho(-10, 10, -10/aspectratio, 10/aspectratio, 1.0, -1.0);

	}else{

		glOrtho(-10*aspectratio, 10*aspectratio, -10, 10, 1.0, -1.0);

	}
	

    

}

int main(int argc,char** argv) {

	glutInit(&argc,argv);
	glutInitWindowSize (500, 500); 
        glutInitWindowPosition (10, 50);
	glutCreateWindow ("Mi primera ventana");	

	glutDisplayFunc(display);
	glutReshapeFunc(cambioventana);

	glutMainLoop();

	return 0;
}