Trying to gradually change prim size?

Hi! This is probably a stupidly simple question, but I'm going to ask the experts here anyway, lol.

I'm trying to write a script that will change the properties of a prim by a small amount when the prim is touched. I've tried to set this up as a touch_start event that randomizes a small vector addition to the current PRIM_SIZE vector value. It seemed like I would want to get the current prim size, then add my random-adjustment to that, then set the primitive parameters to the new value.... but I can't get it to work, and I don't know enough to know why.

Okay, having explained all that, why isn't my script doing the job I describe above?

default
{
    touch_start(integer total_number)
    {
        float xnew1 = llFrand(0.1);
        float xnew2 = -llFrand(0.1);
        float xnew = (xnew1 + xnew2);
        
        float ynew1 = llFrand(0.1);
        float ynew2 = -llFrand(0.1);
        float ynew = (ynew1 + ynew2);

        float znew1 = llFrand(0.1);
        float znew2 = -llFrand(0.1);
        float znew = (znew1 + znew2);

        vector addsize = <xnew, ynew, znew>; 
        vector newsize = llVecMag(llGetPrimitiveParams([PRIM_SIZE]) + addsize);

        llSetPrimitiveParams([PRIM_SIZE, newsize]);
            
    }
}

Not stupid question at all. The thing about llGetPrimitiveParams is it actually returns a *list*, since you can feed it a list of parameter types to get all at once. In your case it's returning a list with a single vector in it, but it's a list just the same, square brackets and all. So do something like this:

vector newsize = llVecMag(llList2Vector(llGetPrimitiveParams([PRIM_SIZE]),0) + addsize);


Maybe not the easiest to read though. Look at this too, same thing in 2 steps.

vector myvector = llList2Vector(llGetPrimitiveParams([PRIM_SIZE]),0);
vector newsize = llVecMag(myvector + addsize);


Hope that helps some

default
{
    touch_start(integer total_number)
    {
        float xnew1 = llFrand(0.1);
        float xnew2 = -llFrand(0.1);
        float xnew = (xnew1 + xnew2);

        float ynew1 = llFrand(0.1);
        float ynew2 = -llFrand(0.1);
        float ynew = (ynew1 + ynew2);

        float znew1 = llFrand(0.1);
        float znew2 = -llFrand(0.1);
        float znew = (znew1 + znew2);

        vector addsize = <xnew, ynew, znew>;
        vector newsize = addsize + llList2Vector( llGetPrimitiveParams([PRIM_SIZE]), 0 );
        llSetPrimitiveParams([PRIM_SIZE, newsize ]);
    }
...
}

You have confused the 'PeimitiveParams'- function calls, see http://www.lslwiki.net/lslwiki/wakka.php?wakka=llSetPrimitiveParams
to learn all about it.

happy scripting

llVecMag returns a Float not a Vector... so what shall it be?

llVecMag returns a float that is the "length" of a vector, so I'm not sure what you're attempting to do with it.

Side note:

I'm guessing you want values from -0.1 to 0.1:

vector current;
vector add;
vector new;

default
{
state_entry()
{
current = llGetScale();
}

touch_start(integer total_number)
{

add.x = llFrand(0.2) - 0.1;
add.y = llFrand(0.2) - 0.1;
add.z = llFrand(0.2) - 0.1;

new = current + add;

if (new.x < 0.01) { new.x  = 0.01;}
else if (new.y < 0.01) { new.y  = 0.01;}
else if (new.z < 0.01) { new.z = 0.01;}
else if (new.x > 10.0) { new.x  = 10.0;}
else if (new.y > 10.0) { new.y  = 10.0;}
else if (new.z > 10.0) { new.z  = 10.0;}

current = new;
llSetScale(new);
}
}

I'm not sure whether or not you actually need the size checks or not.

That part was copy/pasted from the OP, my bad I guess? It seems there is more than one issue with data types going on here

Cool, thanks for all the replies, everyone! You've helped me figure out where I was going wrong, and now it works like it should!