Drift spell

[coolyoshi1]

How would you make a drifting spell like the one from mario kart?

 

[rulerofiron99]

By basing movement on acceleration rather than velocity.

Simplest way is to have two variables for the unit: x velocity and y velocity, let's call them dx and dy (both reals). (google component vectors if you want to understand it better)

The movement trigger, which will fire every 0.03 seconds, simply moves the unit based on dx and dy.

Use custom script: call SetUnitX(udg_unit, GetUnitX(udg_unit) + udg_dx)
and the same for dy, replacing all instances of X with Y in that script.

Next we need a trigger that sets dx and dy.

Since this trigger will be a little more "costly" in terms of calculations required, let's make it every 0.2 seconds or so.

The action will be, once again splitting it into X and Y;
Set dx = dx + (acceleration * cos(facing of unit))
Set dy = dy + (acceleration * sin(facing of unit))

We are adding the acceleration to the existing velocity so that it is gradual; if you want to drift around a corner, as you turn, your car is still going in another direction.
dx and dy can both go negative, to allow for west and south facing movement.

cos & sin are the lengths of sides based on angles in a triangle... do a google search for this as well.

If this all just doesn't make sense to you, I might have a trigger lying around that does this.

 

[coolyoshi1]

hmm ok thanks ill try this

 

[FlamingGlacier21]

By basing movement on acceleration rather than velocity.

Simplest way is to have two variables for the unit: x velocity and y velocity, let's call them dx and dy (both reals). (google component vectors if you want to understand it better)

The movement trigger, which will fire every 0.03 seconds, simply moves the unit based on dx and dy.

Use custom script: call SetUnitX(udg_unit, GetUnitX(udg_unit) + udg_dx)
and the same for dy, replacing all instances of X with Y in that script.

Next we need a trigger that sets dx and dy.

Since this trigger will be a little more "costly" in terms of calculations required, let's make it every 0.2 seconds or so.

The action will be, once again splitting it into X and Y;
Set dx = dx + (acceleration * cos(facing of unit))
Set dy = dy + (acceleration * sin(facing of unit))

We are adding the acceleration to the existing velocity so that it is gradual; if you want to drift around a corner, as you turn, your car is still going in another direction.
dx and dy can both go negative, to allow for west and south facing movement.

cos & sin are the lengths of sides based on angles in a triangle... do a google search for this as well.

If this all just doesn't make sense to you, I might have a trigger lying around that does this.

could you attach the map?

 

[rulerofiron99]

Found it

http://www.epicwar.com/maps/109084/

The system in the map replaces movement with the aforementioned method. Happy drifting.

 

[FlamingGlacier21]

thanks

 

[Elfansoer]

Umm, how if we want to use a polar offset?
Ruleonfire's answer is good, but I'd rather use polar offset than cartesian... Any idea?
(I'm sorry, Cartesius. I'd rather use center-position-based than X-Y-based...)

 

[rulerofiron99]

The problem with polar offset in this case is that the angle would have to be different to the unit's facing angle, so you'll need an index system with variables anyway.

 

[Elfansoer]

Oh... Thanks, rulerofiron, I just think polar offset will also works...

(Heh, you just say his nickname above this, as "ruleonfire". How inconsistent)