# My concertina door is stuck

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I am working on a door that concertinas along its x-axis in order to open and close and I have the concertina part working nicely.

My problem is repositioning the door as it changes size so it remains butted up against the left-hand door post.  It's refusing to reposition!

It is part of a link-set (with link number 2) btw. And I am pretty sure I have the maths right. The trouble appears to be the line that should move the door prim but doesn't.

I am sure that I am missing something blindingly obvious but I cannot for the life of me think what. Help?

```vector door_XYZ; // door position vector
float door_LHS; // x co-ordinate of the left-hand doorpost
float door_SIZ; // door width (variable)
float door_MOD; // the amount by which the door shrinks/grows per iteration of the open/close routine

door_operation(integer mode){
integer i;
for(i = 0; i < 32; i++){
door_SIZ += (mode * door_MOD); // shrink/grow the door
door_XYZ.x = door_LHS + (door_SIZ / 2); // recalcalculate the x co-ordinate relative to the doorpost
llSetLinkPrimitiveParamsFast(2,[PRIM_SIZE,<door_SIZ, 0.01, 3.35>]); // resize the door prim
llSetLinkPrimitiveParamsFast(2,[PRIM_POSITION,<door_XYZ.x, door_XYZ.y, door_XYZ.z>]); // THE BIT THAT DOESN'T SEEM TO WORK
}
}

default{
state_entry(){
door_SIZ = .15; // initial width of the door (open = 0.15; closed = 2.0)
door_LHS = door_XYZ.x - (door_SIZ / 2);
door_MOD = (2.0 - 0.15) / 32;
}
// there's a listen triggering the open/close routine with the appropriate open/close (-1 or +1) parameter
}```

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At first glance, I'm nervous about the integer division in calculating door_LHS and door_XYZ.x -- I'd try switching the divisor to 2.0 instead of 2. I don't know the dimensions here but I'm guessing door_SIZ / 2 == 0.

EDIT: Okay, that's wrong. Hmmm.

Edited by Qie Niangao
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I see a couple problems (been ages since I've scripted, so take me with a grain of salt):
1) I think you are grabbing the LHS position from your door (link #2) not the post (link #1).
2) I think you must use PRIM_POS_LOCAL to move a child prim. That will change the math of your door_LHS assignment.

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Yeah, I think @Madelaine McMasters' #2 is why it's not moving at all: when you get PRIM_POSITION of a child prim, it returns region coordinates, but if you set PRIM_POSITION of a child prim it expects local coordinates, and region coordinates are usually gonna be way beyond the link limits (as well as just wrong). So, yeah, PRIM_POS_LOCAL for both should help a lot.

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Thank you so much everyone. I now have my door moving!

Not moving as intended, I hasten to add. Something to do with the orientation of the door prim itself I think.

It's actually wandering about all over the place at the moment so I do not recommend anyone using the script as it stands.

But movement is good so I can work on the rest.

[UPDATE: wandering door problem solved! And it wasn't the script. My door is actually for a lift (elevator?), parts of which had somehow got rotated when they were linked to form the whole. It now works perfectly so, once again, thank you   *smacking head for not thinking of it myself*]

Edited by clarashymonkey
update