Make a projectile thrown in a curved arc?

Development Programming & Scripting
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1

I’m working on a prototype for a turn based RPG and I’m working on projectiles and am trying to make a grenade projectile that can be thrown at a target. I already have the projectile setup so that it will spawn and hit the intended target. (which is simply since both the launch position and target are fixed positions) All I’m looking to do is have it follow the curved arc, but I have been struggling to find a proper tutorial as they all seem to be based around throwing a grenade at a moving target (which I don’t need since the game is turn-based). I’ve been trying to make use of the suggest projectile velocity but my results either have arcing way to high in the air (that it takes several minutes actually to hit the target.) or it travels too fast I can’t even see it.

Does anyone have any suggestions of better methods to accomplish this or potentially what I might be doing wrong with SuggestProjectileVelocity?

Thanks!

2

Hey @Zanzibarios!

This should be doable, if you bring us your SuggestProjectileVelocity code! Also it shouldn’t matter on the “Throwing a grenade at a moving target” thing, a target is a target, you just take out any extra math that predicts the path of a target.

3

There’s two ways of doing this:

  1. solve the differential equation that lets physics simulation lob the grenade to hit the target
  2. cheat, and build an animation that sends the projectile to the target

The animation in option 2) can be procedural. For example, you could build the projectile something like:

Pseudo-code you can convert to C++ or Blueprint pretty easily:

OnThrow(SourcePos, TargetPos):
  Alpha = 0
  Distance = (TargetPos - SourcePos).Length()
  TimeToTarget = Distance / ThrowSpeed

OnTick(DeltaTime):
  Alpha = Alpha + (DeltaTime / TimeToTarget)
  if (Alpha >= 1):
    Alpha = 1
    Explode()
  Position = SourcePos + (TargetPos - SourcePos) * Alpha + HeightForAlpha(Alpha)

HeightForAlpha(Alpha):
   Beta = (Alpha - 0.5) * 2
  return Distance * (1 - Beta * Beta) * Vector.Up
4

Suggest Projectile velocity is focus on the speed,you can adjust the flying speed,but the arc is hard to control.(faster the speed is,straighter the line is).

if you want more control on the arc,you could use another one,called suggest projectile custom arc,which you can adjust the arc on it.
But the speed is fixed.

And another way is like they said.
Make a timeline animation for it.
That way you can fully control the arc and speed.