#include <windows.h>  
#include <gl/glut.h>

float v=150;
float t=0;
float a=-9.81;

void inicializa(void)
{
    glClearColor(0.6,0.8,1.0,0.0);		
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0, 640.0, 0.0, 480.0);
}
void dibuja(void)
{
    float x,y;
	glClear(GL_COLOR_BUFFER_BIT);
    x = v*t;                      // ecuaciones
    y = .5 * a * t*t;             // movimiento
    glColor3f(.6, .2, 0);         //cafe
    glRecti(0+x,389+y,100+x,397+y);
    glColor3f(0.3, 0.3, 0.3);  	   //gris    
	glBegin(GL_TRIANGLES); 	
		glVertex2i(100+x,380+y);	
		glVertex2i(130+x,393+y);	
		glVertex2i(100+x,406+y);	  
	glEnd();			
    glColor3f(.8, 0, 0);  	   
	glBegin(GL_QUAD_STRIP); 	
		glVertex2f(-20+x,385+y);		
		glVertex2i(-5+x,385+y);		
		glVertex2i(-12+x,393+y);	
		glVertex2i(4+x,393+y);	
		glVertex2i(-20+x,401+y);
		glVertex2i(-5+x,401+y);	
	glEnd();	
	glutSwapBuffers();								 
}
void tiempo(void)
{
     t += 0.05;
     glutPostRedisplay();
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);         			
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); 
	glutInitWindowSize(640,480);      
	glutInitWindowPosition(100, 150);  
	glutCreateWindow("Flecha");   
	inicializa();            
    glutIdleFunc(tiempo);    
	glutDisplayFunc(dibuja);        
	glutMainLoop(); 	
    return 0;	    
}