[JASS] Formula is imprecise?

[Molekyle]

So I'm trying to move this unit in a circular motion and everything is working out perfectly fine apart from one thing, the radius keeps increasing by a tiny amount. Over a short span of time this would not be visible - but this is not the case.

This is the code and the formula for the circular motion that I'm using:

set u1 = gg_unit_n001_0000
set u2 = udg_UNIT_Dummy[1]
set x1 = GetUnitX(u1)
set y1 = GetUnitY(u1)
set x2 = GetUnitX(u2)-x1
set y2 = GetUnitY(u2)-y1
set d = SquareRoot(y2*y2+x2*x2)
call ClearTextMessagesBJ( GetPlayersAll() )
call DisplayTextToForce( GetPlayersAll(), R2S(d) )
set a = Atan2(y2,x2)+7.50*bj_DEGTORAD
call SetUnitPosition(u2,x1+d*Cos(a),y1+d*Sin(a))
call DestroyEffect(AddSpecialEffectTarget ("war3mapImported\\BlackKeeperMissileNoSound.mdl", u2, "origin"))
set u1 = null
set u2 = null

 

[Starquizer]

I can't see anything wrong with the math ?

Is unit u1 has a fixed position ?

 

[rulerofiron99]

Save the unit's angle from the center of the circle to a variable, and update that instead.

set u1 = gg_unit_n001_0000
set u2 = udg_UNIT_Dummy[1]
set x1 = GetUnitX(u1)
set y1 = GetUnitY(u1)
call SetUnitX(u2, x1 + d * Cos(angle))
call SetUnitY(u2, y1 + d * Sin(angle))

d and angle should be saved globally.

 

[Molekyle]

I can't see anything wrong with the math ?

Is unit u1 has a fixed position ?

Yes u1 does have a fixxed position.

Save the unit's angle from the center of the circle to a variable, and update that instead.

set u1 = gg_unit_n001_0000
set u2 = udg_UNIT_Dummy[1]
set x1 = GetUnitX(u1)
set y1 = GetUnitY(u1)
call SetUnitX(u2, x1 + d * Cos(angle))
call SetUnitY(u2, y1 + d * Sin(angle))

d and angle should be saved globally.

I suppose I'll try that, I'll report back with the results :>

 

[Molekyle]

It worked! Thanks alot rulerofiron99

 

[Starquizer]

It worked! Thanks alot rulerofiron99

So, what was wrong; you were using the "d" and "a" locally ?

 

[rulerofiron99]

So, what was wrong; you were using the "d" and "a" locally ?

The problem isn't exactly that they were locals; the script was recalculating the distance every iteration, and distance increases when the unit moves.

My script uses a set distance, and performs angular momentum.

 

[Maker]

Often it is better to save the cos and sin values rather than then angle, no need to recalculate them during every loop since they return the same value each time.