# Gravity-Bound Projectiles that Trace Position

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### » Wed Jun 08, 2016 12:43 am

In some games, such as Mega Man (again), there are some enemies that have the ability to fire shots that somehow manage to both get your X position and yet at the same time throw shots in an arc.
https://youtu.be/aZMXvt1kppc?t=1m36s

Is there any way to possibly emulate this in Construct 2 (either using behaviors or purely through events)?
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### » Fri Jun 10, 2016 11:44 pm

maybe every tick create a track sprite at object.x and object.y?
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### » Sat Jun 11, 2016 2:21 am

What gumshoe said pretty much...

Every tick; (or every X seconds for a slower angle correction)
- Set angle of projectile.sprite towards player.X,player.Y

On "enemy shoot"
- create projectile.sprite at enemy.X,enemy.Y
- set angle of projectile.sprite to (something not already aimed towards the player - maybe straight up?)

Note, the faster your projectile and the slower it angles itself will all affect the arcing motion.

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### » Sat Jun 11, 2016 2:48 am

there have been other topics for that. The equations for the motion of a falling projectile is this:

y1=y0+vy*t+0.5*gravity*t^2
x1=X0+vx*t

X0,y0 is the start position
X1,y1 is the end position
Vx,Vy is the velocity
t is time

If you pick a time and then solve those equations for vx and vy that would do it.

I think it's referred to elsewhere as predictive aiming. You could also Google kinematics for more tutorials about the equations used.
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