Unit facing direction

[casperjeff]

Part of my AI's formations logic will need to determine a unit's facing direction (as well as the need to face units in a certain direction).

I'd hate to think that the only way to 'face' a unit in a particular direction was to create a bogus move command and then stop the unit once movement starts (heck, tanks can turn in place pretty easily).

Is there any way to determine the 'direction' a unit is facing (radians? degrees? cardinal direction?)? (other than tracking previous movements and extrapolating based on straight line analysis?)

Is there any way to 'face' a unit in a particular direction without crazy unnecessary movements?

I am assuming that units can 'fire' in any direction regardless of what direction the vehicle is facing?

Can any BA units turn in place or is the 'turn rate' for each unit involved?

[Kloot]

Is there any way to determine the 'direction' a unit is facing (radians? degrees? cardinal direction?)? (other than tracking previous movements and extrapolating based on straight line analysis?)

No.

Is there any way to 'face' a unit in a particular direction without crazy unnecessary movements?

No.

I am assuming that units can 'fire' in any direction regardless of what direction the vehicle is facing?

Depends on a unit's armament (weapon aiming restrictions, etc), but true for many *A units.

Can any BA units turn in place or is the 'turn rate' for each unit involved?

All unit types can perform in-place turns below a certain limit (which defaults to 15 elmos per second; AI's can not read the actual value), but this only kicks in when a unit's turning speed is less than its wanted speed.

[casperjeff]

No.

Grumble.
Just a little more work for me.

[yuritch]

I had to code my own 'turn in place' command for Spring 1944 units in lua. Spring engine isn't really suited for non-360 degree turreted weapons (or at least their support is far from perfect), as well as some other features not usually found in *A mods.

My solution can be extended to other games/mods, but that requires changes to those mods, which no AI should do, so it's hardly of use here (unless some engine dev implements a similar feature into Spring itself).

[casperjeff]

thanks....I'll be ok I think.

[casperjeff]

All unit types can perform in-place turns below a certain limit (which defaults to 15 elmos per second; AI's can not read the actual value), but this only kicks in when a unit's turning speed is less than its wanted speed.

Can you elaborate on this?
Between all these functions, I figured I should be able to get arbitrary units to 'turn in place' or at leas move in a minimal direction enough to face the direction of movement when complete (dynamically based on unitDef)

getTurnInPlaceDistance()
Units above this distance to goal will try to turn while keeping some of their speed.

getTurnInPlaceSpeedLimit()
Units below this speed will turn in place regardless of their turnInPlace setting.

getTurnRadius()

getTurnRate()

I've tried changing wanted speed to match at/below/above the turninplace speed limit (with little/no effect), tried various distances for movement but each unit requires unique values....

Any ideas?

[Tobi]

I recall I experimented some time with a nearby (say 100 elmos or so) CMD_MOVE plus a CMD_SET_WANTED_MAX_SPEED very close to zero (0.001 or so), and IIRC this worked decently to turn a unit while keeping it almost in same place.

Note the move command needs to be far enough away from the unit or it will think it has reached it's destination already and it will stop. Also it needs small but non-zero wanted max speed IIRC, or the unit just won't move/turn at all.

[casperjeff]

Thanks...I will try this tonight. I did not experiment with wanted speeds that low....

I apologize...can somebody give me a rundown on the term 'elmo'? Elmos as a rate means to me 'how many Elmo's big bird can eat per second...which is about 2.4'

[Tobi]

It's the semi official unit of measurement used for distances in Spring.

1 elmo = 1 map texture pixel = 1/8 map heightmap pixels

Coordinates for commands, unit positions, etc., all are measured in 'elmos'.

[casperjeff]

Got it to work. Pretty nifty. Thanks much!!

Code: Select all

    
private void rotateUnit(COCUnit unit, float angle){
        float DISTANCE=100f;
        float SPEED = 0.002f;
        float toX = (float)Math.cos(Math.toRadians(angle))*DISTANCE;
        float toZ = -(float)Math.sin(Math.toRadians(angle))*DISTANCE;
        float toY = unit.getUnit().getPos().y;
        AIFloat3 moveTo = new AIFloat3(unit.getUnit().getPos().x+toX, toY, unit.getUnit().getPos().z+toZ);
        AICommand command = new MoveUnitAICommand(unit.getUnit(), 0,new java.util.ArrayList(), 1000, moveTo);
        handleEngineCommand(command);
        command = new SetWantedMaxSpeedUnitAICommand(unit.getUnit(), 0,new java.util.ArrayList(), 1000, SPEED );
        handleEngineCommand(command);
    }

[zwzsg]

You must mean 1/8, not 8.

[Tobi]

Ah, yes, thanks, fixed now.