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Prim falls through floor

Paladin Pinion
The other one of 10
Join date: 3 Aug 2007
Posts: 191
01-18-2010 15:29
I want to apply impulse to a small box prim 0.5 x 0.5 x 0.1 when it's clicked. The prim is non-physical initially. When clicked, I turn on physics and apply a small impulse. When a collision is detected, I turn off physics and set the prim to phantom. I use both collision_start and land_collision_start to detect collisions. This works great on the ground.

In a skybox, as soon as physics kicks in, the prim goes right through the floor before any impulse can be applied. I have tried raising the prim a little bit on the z axis before turning it physical (so it will be above the floor before physics turns on) but that doesn't help.

Is there a way around this? Or is this another case of a small prim falling through the gaps in Havoc's location checks? I do notice that sometimes it falls through the ground too, though only rarely, and at least it always pops back up again in a second. In a skybox it has never once worked.
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Void Singer
Int vSelf = Sing(void);
Join date: 24 Sep 2005
Posts: 6,973
01-18-2010 16:10
a lot depends on the size of the object, it's speed, and the thickness of the floor.... reinforcing the floor by either thickening it, or placing overlapping prims in the same location (they can be exactly the same size and position).

reinforcement gives the physics engine more chances to catch the item before it passes the point of no return for slipping by. if the sim is lagging already, sometimes even those tricks won't help. physics over 4km tend to be goofy too.
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Nika Talaj
now you see her ...
Join date: 2 Jan 2007
Posts: 5,449
01-18-2010 16:16
Set its buoyancy before you make it physical. Careful - a little buoyancy goes a long way!

:)
Paladin Pinion
The other one of 10
Join date: 3 Aug 2007
Posts: 191
01-18-2010 17:46
From: Nika Talaj
Set its buoyancy before you make it physical. Careful - a little buoyancy goes a long way!

:)


What a good idea. I thought the engine would ignore and discard physical commands if the object was non-physical. So they're permanent properties? That opens the door to lots of stuff...
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Johan Laurasia
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Join date: 31 Oct 2006
Posts: 1,394
01-18-2010 17:50
From: Void Singer
a lot depends on the size of the object, it's speed, and the thickness of the floor.... reinforcing the floor by either thickening it, or placing overlapping prims in the same location (they can be exactly the same size and position).

reinforcement gives the physics engine more chances to catch the item before it passes the point of no return for slipping by. if the sim is lagging already, sometimes even those tricks won't help. physics over 4km tend to be goofy too.


Reminds me of the time I was working on a physical object that had a bunch of small parts. I went to edit it and edit linked parts to get a a particular prim, and when I selected the 1 prim, the rest fell, right through my platform about 700 meters down to the ground. A few items that drifted off my property got returned (some right away, some days later), and I went down below to 'clean up', but I had a pretty extensive build on the ground at the time with roads and the whole 9 yards. Used every trick in the book to find and get all the pieces parts, and eventually I was fairly certain I had got them all, until I eventually sold the land, and when I pulled down my build and did a prim search, there was still 2 or 3 parts left.

The solution was simple enough though, after that, I coded the device so that when I stopped it, it would return to non-physical, so editing it wouldn't cause the disaster I had.

Btw, a friend was there, and couldn't stop laughing watching all those prims fall to pieces, through the floor, and down to the ground. (It was funny actually).
Void Singer
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Join date: 24 Sep 2005
Posts: 6,973
01-18-2010 18:21
did that mayself once or twice (or more... I never learn)

I should mention, I've found that coincidental prims (same siz/pos/rot/etc) are better at making physics behave than larger prims... especially when I layer in 5-10 of them for bearings.... and set type to glass. they are also good for adding weight for leverage.
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Paladin Pinion
The other one of 10
Join date: 3 Aug 2007
Posts: 191
01-18-2010 18:27
I've been doing the exploding prim thing for a couple of days now. :) I was amused the other day when I received a message that my eye had been returned to me because it went offworld. And to think I hadn't even missed it.

Anyway, in spite of my high hopes, setting buoyancy doesn't work. I have to turn it off immediately after the impluse, or the prim won't collide with anything, it just sails along in the air. I need it to fall back to the ground or the floor and trigger a collision.

I tried llSetHoverHeight too with the same non-results. Basically I just want a click to give the prim a little push, let physics carry it a bit, and then have it fall to the floor again.
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Paladin Pinion
The other one of 10
Join date: 3 Aug 2007
Posts: 191
01-18-2010 20:48
Oh wait -- it does work. I had an error elsewhere in my script. That's a good trick. Thanks!
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Nika Talaj
now you see her ...
Join date: 2 Jan 2007
Posts: 5,449
01-18-2010 20:57
From: Johan Laurasia
the rest fell, right through my platform about 700 meters down to the ground.
I'm always amazed that prims don't leave craters when I accidentally 'drop' them from 3700 feet up. I've taken to putting a suicide script in physical things I'm working with so that if I haven't changed them for a few hours they die, lol!

Glad the buoyancy worked out!
:)
Johan Laurasia
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Join date: 31 Oct 2006
Posts: 1,394
01-19-2010 01:22
From: Nika Talaj
I'm always amazed that prims don't leave craters when I accidentally 'drop' them from 3700 feet up. :)


Oooh, that sounds like a fun scripting challenge though... using land collision events combined with llModifyLand() to make bombs that leave creators in the ground :)
Void Singer
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Join date: 24 Sep 2005
Posts: 6,973
01-19-2010 07:56
From: Johan Laurasia
to make bombs that leave creators in the ground :)

I'm sensing a freudian slip of your opinion about certain weapon makers (maybe the ones that make griefing weapons?)
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Johan Laurasia
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01-19-2010 21:04
From: Void Singer
I'm sensing a freudian slip of your opinion about certain weapon makers (maybe the ones that make griefing weapons?)


Duh me... no a Firefoxian slip... I meant craters, but I got the underlined and Firefox corrected it to creators and I missed it. As a content creator myself, I don't support blowing up creators :)
Void Singer
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Join date: 24 Sep 2005
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01-19-2010 22:43
that's a shame... I can think of a few whom I'd like to.... in SL at any rate.
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