EJEM_02_02.c

/*     USO DE gluPerspective     */

/*   gluPerspective(ANGULO(y), int(ANCHO/ALTO), Z_CERCA, Z_LEJOS)   */

#include <GL/glut.h>
#include <unistd.h>

void PintaEjes()
{
	glBegin(GL_LINES);
		glColor3f(1,0,0); glVertex3f(-5, 0, 0); glVertex3f(5, 0, 0);
		glColor3f(0,1,0); glVertex3f(0, -5, 0); glVertex3f(0, 5, 0);
		glColor3f(0,0,1); glVertex3f(0, 0, -5); glVertex3f(0, 0, 5);
	glEnd();
}

void Gradua  ( )
{
	int k=0, x1,y1,x2,y2;

	glBegin(GL_LINES);
	glColor3f(1,0,0); for(k=1; k<10; k++) { glVertex3f(-5+k, 0.2, 0); glVertex3f(-5+k, -0.2, 0); }
	glColor3f(0,1,0); for(k=1; k<10; k++) { glVertex3f(0.2, -5+k, 0); glVertex3f(-0.2, -5+k, 0); }
	glEnd();
}

void Dibuja(void)
{	
	glClearColor(0.0,0.0,0.0,0.0);
	glClear(GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(-5.0,5.0, -5.0,5.0, -5.0,5.0);
	PintaEjes( ); Gradua( );
	glMatrixMode(GL_MODELVIEW);
	gluPerspective(60.0,1.0,1.0,100.0);
	glTranslatef(0.0,0.0,-3.0);
	glBegin(GL_LINES);
		glColor3f(1.0f, 1.0f, 0.0f);
		glVertex3f(-2.0f, -2.0f, 2.0f); glVertex3f(2.0f, -2.0f, 2.0f);
		glVertex3f(2.0f, -2.0f, 2.0f); glVertex3f(2.0f, 2.0f, 0.0f);
		glVertex3f(2.0f, 2.0f, 0.0f); glVertex3f(-2.0f, 2.0f, 0.0f);
		glVertex3f(-2.0f, 2.0f, 0.0f); glVertex3f(-2.0f, -2.0f, 2.0f);
	glEnd();
	glFlush();
	sleep(20);
	exit(0);
}

int main(int argc, char ** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
	glutInitWindowPosition(200,150);
	glutInitWindowSize(1000,500);
	glutCreateWindow(argv[0]);
	glutDisplayFunc(Dibuja);
	glutMainLoop();
	return 0;
}