Limiting direction on flexible objects

Flexible objects are amazing and show great oppurtunity. Unfortunately you need to be quite inventive if you want to have them look a bit realistic.

I understand why they are better off being phantom but will there ever be a way to limit the directions they can flex too? It would not make everything look natural but it would help a lot simulating something resting on a surface.

For example if you make a cape now and walk backwards it'll have the nasty habit to go right thru you. You can offset it a bit by rotating the object so that it flexes a lot better towards the back but it's not all that easy to do if you want to keep a nice look. If we could limit in what direction it can flex on an axis we'd have less issues. It won't look totally natural but it would look ok or at least similar to what we'd get in 1.9 when moving in a less ideal direction and it would look fabulous when walking in the intended direction.

Until SL gets proper cloth/fabric physics, I wouldn't expect much more development on flex prims which tend to lag the client enough as it is WITHOUT being physical and SL having to deal with av collision detection (on an attachment, no less).

However, flex prims CAN have pseudo-sorta-limited rotation by changing the "gravity" amount: 10 will push it down, -10 up (yes, backwards but it's a gravitational force vector). Then set "wind" to 0 and, possibly, the other settings to 0 too. Rotating the flex prim like this (or when frozen after bent by the wind) will cause some interesting twisting (especially when combined with the "twist" param). Unfortunately, flex prims tend to reset/twitch when the camera zooms out (perhaps an LOD artifact) and if will reset regardless when moving in/out of the draw distance.

There are several ways to deal with this.

1. Gravity
2. User-defined constant force away from the avatar (not yet implemented but has been suggested and I believe it's a good idea)
3. Avatar and ground collisions. These would take some time to implement, but would be done client-side and would be an optional feature. Perhaps in the next version of Flexible Objects.

I'd like for the cape to have total freedom when walking forward but having a lot less when walking backwards. I don't see how gravity can help a lot. The only gravity related trick I've found upto now is that you can use it to make a rotated flexprim bend towards the ground so that it is less obvious that it is prerotated away from the avatar.

Note that gravity will be quite useful in combination with number 2 as it would help to get a somewhat natural look.



This could prove to be quite useful though maybe a bit limited in scope.



That would be fabulous, I'd be more than happy if we'd need to settle for lesser intermediate solutions.

Once the scripting calls are in you could stiffen the cape when walking backwards.

Yes I have thought about it too. Though that would be less nice when it comes to server load off course.

Just a thought, no idea if it'd work, but it might also be possible to limit it to an extent by having the prim pointing back away from your avatar rather than downwards.

This works to some extent. If I understand you correctly you are referring to what I describe here:



So first you rotate it away so that it's close to you at the top but not at the bottom. Then you use gravity to pull it down which will make it flex and it'll also come closer to you (as it can not grow in size moving closer to to ground requires it to come closer to you). This works a bit but it is far from easy to make it look natural nor does it solve the problem in many cases.

Oh, indeed it is. Should re-read threads before posting really.

This is now be possible with the "force" llSetPrimitiveParams PRIM_FLEXIBLE parameter:

// llSetPrimitiveParams([PRIM_FLEXIBLE,
//								  boolean on,
//								  integer softness,
//								  float gravity,
//								  float friction,
//								  float wind,
//								  float tension,
//								  vector force]);
llSetPrimitiveParams([PRIM_FLEXIBLE,1,3,10,10,0,10,<.1,0,0>]);

No, it's not in the same order as the object editor (which doesn't have a "force" option either). Yes, I already submitted a but report about both.

Oooh! Vector force! That could allow you to use pre-flexed flexible prims for building.

Thanks for pointing that out, Argent -- I would never have noticed that!

Indeed, that's just the sort of thing I was wishing for when I was messing around with flexiprims trying to figure out a way to make them bend in a direction other than straight down or up. If this is accurate, I'd be one happy fox!

One question: For attachments, is the vector global, relative to the attachment point, relative to the root, or local to the (child) prim? I'm at work, so I can't test it for myself right now.

Props to Eep Quirk, actually.

Ah, true that! I should get my eyes checked.

Vector Force! Merge to form FLEXITRON!

Sorry, couldn't resist.

Psyra, Psyra, Psyra...

More than ever I wish you'd made your bird avatars moddable.

I can't play with flexible feathers on my Magpie!

AUGH!

Please, I'll buy another one, just... make 'em moddable...

I just wrote a little script using this force parameter... and creates a kind of carnivorous plant that's attracted to avatars. Set up a double-row of them in Sandbox Goguen, and it's pretty amazing watching them worshipping Stillpink Sandgrain.