# How do I Make Parabolic Projectile and Movement

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• 11 posts
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Calculate parabolic trajectories and tween objects over them.
• Hi guys... i was wondering if you could lend me some of you wisdom in the fiel of mathematics and C2

im looking for a bullet that will travel in a parabolic way (like castlevania's skeletons)... and hit the player, but not ramdom, but with precision (see the picture attached) i can make a parabolic bullet but i cant do it that it will always fall where the players is... so if he does not moves it will hit him.

how do you do it??? 0:

another thing if its possible to implement this to make enemies jump in a parabolic trajectory and fall in the player... that would be awesome...

thanks in advance, any help will be appreciated

• Graphics looks really nice

The bullet behaviour has gravity. Just try to play around with that I guess.

• Here is a capx with a few different methods:

/examples22/cannon.capx

https://www.dropbox.com/s/f651hqzv53u23 ... .capx?dl=1

The first method uses a fixed speed and finds an angle. The angle is NaN if there is no solution.

The second uses a fixed angle and finds a speed. The angle is NaN if there is no solution.

The third is like the second but the angle is always pointed above the target so there always is a solution.

Finally the bullet behavior wasn't used since the path isn't accurate when using gravity.

• Here is a capx with a few different methods:

https://dl.dropboxusercontent.com/u/542 ... annon.capx

The first method uses a fixed speed and finds an angle. The angle is NaN if there is no solution.

The second uses a fixed angle and finds a speed. The angle is NaN if there is no solution.

The third is like the second but the angle is always pointed above the target so there always is a solution.

Finally the bullet behavior wasn't used since the path isn't accurate when using gravity.

i will check it out =) thanks a lot...and report findings

btw your plugins are awesome... and many of my game's features could not be possible wihtout you =) thanks

you surely will appear in my game with other user that are so firendly and helpful XD

• Awesome example, mod speed mode is so close to what i need as the flight time seems to remain the same no matter how far away i click from the cannon. Changing the angle (to Mouse.Y-400 rather than -200, for example) alters the flight time, is there a way i can have fixed flight time regardless of the angle? I'd like to have 3 projectiles that have different angle but same flight time so they all hit the target at the same time.

• is it possible to combine this with Turret behavior ?

• Having a fixed flight time and having a different launch angle isn't physically accurate since it requires each cannonball to have a different gravity.

Do do a launch here are the formulas. "angle" is the launch angle and t is the flight time. You'll need to change event 5 to use ball.gravity instead of gravity in the equations.

ball set vx to (x_target-x_start) /t

ball set vy to ball.vx*tan(angle)

ball set gravity to 2*(y_target-y_start-ball.vy*t)/t^2

Probably no, the turret behavior is for straight shots, but with some creativity you possibly could do something similar with events.

• Can this be done without using gravity then? Like a formula to follow an arc from point A to point B, with a specific angle and flight time? There has to be a way...

• It can be done by modifying the capx with the info from my last post, or you could setup a function to do a Quadratic Bezier Curve, which is like lerp but you can do this:

http://en.wikipedia.org/wiki/B%C3%A9zie ... tic_curves

and here's the math for it:

http://en.wikipedia.org/wiki/B%C3%A9zie ... ier_curves

The math doesn't look much simpler:

https://dl.dropboxusercontent.com/u/542 ... /qarp.capx

You can change up the path by changing xmid and ymid to another location.

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• Thanks, i will experiment with this.

• I really needed this. thanks

• 11 posts