Unit Faces Unit?

[Deleted member 219079]

My current checking method;

    private constant function Positive takes real r returns real
        if r < 0 then
            return -r
        endif
        return r
    endfunction
    
    private function UnitFacingUnit takes unit u, unit u2 returns boolean
        return Positive((bj_RADTODEG*Atan2(GetUnitY(u2)-GetUnitY(u),GetUnitX(u2)-GetUnitX(u)))-GetUnitFacing(u))<5.
    endfunction

Does some crazy stuff from time to time.

If nobody can spot anything errors from it, I guess the bug lingers somewhere else in my code...

 

[Dr Super Good]

Atan2 returns from +180 to -180 if I recall and unit facing is from 0 to 360.

If the unit is facing 179 degrees (almost straight to the left but a tad up) yet the target is at -179 degrees (almost straight to the left but a tad down) the result is -358. When put through your positive function you get...

358 < 5.0 which is false.

However in reality the unit was only 2 degrees off a direct facing which should be true.

The solution is to not test the angle for deviation but the sin/cos of the angle. Unlike the returned angle from Atan2 which is discontinuous, the sin/cos of an angle is continuous and in effect converts the discontinuous angle into a continuous angle based number.

Since you are after deviation from facing the logical one to use is COS which is 1 at 0 and falls to 0 at 90/-90 and to -1 at 180/-180. Thus your entire return condition becomes...

    private function UnitFacingUnit takes unit u, unit u2 returns boolean
         return Cos(Atan2(GetUnitY(u2)-GetUnitY(u),GetUnitX(u2)-GetUnitX(u))-bj_DEGTORAD*GetUnitFacing(u))<0.996194
     endfunction

Where 0.99619469809174553229501040247389 is Cos(5degrees).

 

[Deleted member 219079]

Is that guaranteed to work? Can't get it to work..

 

[Dr Super Good]

Is that guaranteed to work?

I do hope so, but there is always the chance of some mistake as I have not tested it.

Check the result returned by

Cos(Atan2(GetUnitY(u2)-GetUnitY(u),GetUnitX(u2)-GetUnitX(u))-bj_DEGTORAD*GetUnitFacing(u))

It should be very close to 1 when facing a unit and -1 when facing away from a unit.

 

[Deleted member 219079]

Then the error must be in the following function:

private static method dummyMotion takes nothing returns nothing
            local unit u = GetEnumUnit()
            local integer i = GetUnitUserData(u)
            call SetUnitZ(u, DUMMY_HEIGHT + Pythagoras(GetUnitX(u)-GetUnitX(s.target),GetUnitY(u)-GetUnitY(s.target))*0.5)
            if not UnitFacingUnit(u, s.target) then
                    if FACES[i] then
                        set FACE_ANGLE[i] = -FACE_ANGLE[i]
                        set FACES[i] = false
                    endif
                    set FACING[i] = FACING[i] + DUMMY_TURN_SPEED*FACE_ANGLE[i]
                    call SetUnitFacing(u, FACING[i]*bj_RADTODEG)
                    call ChangeMotionAngle(u, FACING[i])
                else
                    set FACES[i] = true
                endif
        endmethod

Erratic movement; the turning stops after a while:

Edit: I know I can't put others to fix my code, I'll probably just dump the whole spell...

 

[Dr Super Good]

Erratic movement

No movement is erratic. The deterministic nature means it is all predictable but might not make sense. Please post an example map demonstrating this behaviour.

A rough guess is that you may not be converting degrees to radians (or back) correctly somewhere. Using degrees instead of radians will produce pretty crazy and seemingly random angles.

 

[Ceday]

The function UnitFacingUnit Dr Super Good told you actually gives inverse result.Use a "not" at the return value.(I will test soon)

 

[Dr Super Good]

The function UnitFacingUnit Dr Super Good told you actually gives inverse result.Use a "not" at the return value.(I will test soon)

Ops...

 

[Deleted member 219079]

I scrapped the spell, couldn't get it work.

Thanks for all the help anyways...