Move two linked child prims at the same time?

I'm building a project where I need to move two linked child prims at the same time, and have them move in a synchronised fashion so they don't seem to be moving out of step with each other. The movement itself is very simple, just a straight line.

I've been using llSetLinkPrimitiveParams and adjusting the prim position. The problem I'm having is the 0.2 second delay means that between moving one child then moving the other child, there's that 0.2 second delay which is obvious enough that it doesn't look right. Ideally I'd have liked to be able to feed two link numbers to llSetLinkPrimitiveParams but that doesn't appear to be possible.

I've considered putting separate scripts in each of the two child prims and then triggering them with a link message, but I'm concerned that this will just trade one timing problem for another -- I've seen the link messages fail now and then, and the only thing that would be worse than the two prims moving out of step with each other would be one of them not moving at all, so I'd like to keep everything within a single script if that's at all possible.

So, I'm hoping someone else may have come across this and come up with a solution? Thanks!

-Atashi

I think your heading in the right dierection to control them via separate scripts and trigger them with a single LinkdMessage.

I just did this recently to syncronize some stuff on my Storm Cloud security device and the sync was pretty good. I also did this to synchronize a texture change across about 100 prims on another project and that too worked pretty good.

Linked Messages are wonderful for this sorta stuff.

-Phidian

Can't you use a linked message that triggers a llSetPos; they don't have delay.. unless you're trying to move it really far along the line. Then i'm not quite sure, though you could use WarpPos, though that might be a little too fast.

A little trick I use a lot of times with no time penalty is either llSetColor/llSetAlpha or llSetLinkColor/llSetLinkAlpha. If you have a face that is not visible in the child prim or you can just make them hollow etc. Send the message to change alpha on only that face in each prim and then use something like this in each one you want to move:

default
{
	changed(integer change)
	{

		float alpha = llGetAlpha(5);//number of the face here
		if(change & CHANGED_COLOR)
		{
			if(alpha > 0.5)
			{
				llSetPos(<0.0.0>);//wherever
			}
			else
				llSetPos(<0.0.0>);//wherever else
		}

	}
}

You might also be able to use a single call to llSetLinkPrimitiveParams(), with concatenated lists for each child prim ?

[Edit]Ack, no, it won't do, the function only allows one set of prim params.

Thanks for the suggestions everyone! I tried using llSetPos but it too incurrs a 0.2 second delay.

I will try using a pair of scripts that are triggered in tandem by a link message and see how that works. As long as the link message works, it ought to allow things to happen in sync - or at least close enough that people don't really notice any slight delays or stutters.

-Atashi

That's what I do in creature animation, it works great. You can also use chat as a good alternative to link message.

I wrote a couple of timer scripts that are in the Forums Script Library.

You could adapt them to be pretty precise. Instead of sending a message to each child saying Do X Now...you send a message that says Do X at time YYYY. (YYYY could be only a few milliseconds in the future. The timers are accurate to better than a tenth of a second.

I have a demo I could send you...it is a bunch of boxes that rotate at exactly the same instant even though they do not exchange messages.

/15/24/184642/1.html

/15/4c/180313/1.html

About sending messages...

Delivery is not guaranteed. That is, you can send one and it will never arrive. It is designed that way. Live with it.

One simple band-aid is to send every message two times or more, and design the protocol so that receiving two copies of the same message is OK.

Also, order of arrival is not guaranteed. You can send A followed by B, and they both arrive, but B arrives first. Fun, eh? They don't even need to arrive at different objects in the same order.

And so many times I've asked myself whether all that check code was worth all the time and effort in the end since nothing is ever guaranteed (not even owning things you purchased - i.e. inventory loss).

Yea - I'm just whining

Try this...
Create two new scripts, each using llSetLinkPrimitiveParams, targeting their respective prims, but place them in the same prim

use one llMessageLinked call targeted at the prim they are in to trigger them both

I've never seen one script in a single prim get a link message and another in the same prim NOT get it... so if it fails, neither child moves

...in fact I don't believe I've ever seen failures except when using LINK_ALL, LINK_ALL_OTHERS, or LINK_ALL_CHILDREN....

anyone feel free to chime in if they have

Thanks Void -- that's what I was thinking of doing, in fact. Where I have the one script calling llSetLinkPrimitiveParams twice, I'd replace that with a llMessageLinked call to LINK_THIS then have two more tiny scripts in the same prim, each calling llSetLinkPrimitiveParams once when they hear the right link message from LINK_THIS

Will be trying it out when I can get inworld later today.

-Atashi