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Matti Deigan added a comment - 29/Sep/07 04:23 AM
Phantom Objects don't go through the ground even on the Havok2 engine. (llVolumeDetect sets objects phantom) so I say its a bug fix. otherwise there would be objects floating under the sim's calculations and messing up the sim due to prims that cant be found.
Phantom objects in the old havok collided with the ground. The only way to have something NOT collide with the ground was to use llVolumeDetect(). I've used this in the past to get around the fact that phantom objects collide with the ground. I couldn't move the ground, because of ANOTHER annoying limitation: avatars can't fly under their own power a certain height above the land surface.
So I think if this change remains in place, we need a "[ ] Really phantom, no kidding" option that goes through the ground. hmm. I've always found accidentally dropping things through the ground to be highly annoying. I fail to see what possible use there could be for this, that can't be done otherwise. THe example of the mario coiins, you could simply have them llDie() on collision with the land. Since that's essentially what's happening anyways, unless they're getting returned to ypou,. which would be spammy.
Well, alright, I can come up with one concrete example for you. It just takes awhile to explain all of the competing constraints.
The place where this was an issue was the sim Suffugium. Go there and look at the Police Drones that float around and scan you. Specifically take note of the large cone-shaped prims. The idea is that the drones should be able to float freely around and scan people, and since trying to design a path-finding algorithm to get around walls would be too difficult in LSL, I opted to have the drones be phantom. In the northern-center part of the sim, there's a big black saucer-shaped arena for a game called Holoball. The game is played by flying around in the arena, so it's important that players are able to fly freely. The rules disallow the use of flight-assist attachments. Since the ceiling on unassisted flight in SL is based on the height of the land, it was necessary to raise the land up underneath the arena. The land is fairly close to the ground under the arena so that all areas of the arena are accessible by unassisted avatar flight. Normally the police drones float 5-10m above the street level. However, when they chase an avatar to scan them, it's necessary to dip lower. The bounding box for the cone-shaped light prim hits the ground in the area below the arena. The only way to avoid this is to set the police drones to llVolumeDetect() so that they don't impact the terrain. (Currently I have llVolumeDetect() disabled due to yet ANOTHER constraint: when the police drones interpenetrate with the (non-phantom) automated vehicles, many collision() events are generated which drops the physics FPS drastically. Right now, I have the police drones react to a land_collision() by giving up chasing an avatar. I find this solution rather sub-optimal.)
Ryozu Kojima made changes - 29/Sep/07 01:08 PM
These cone prims are still attached to the drone, though. Part of the same object. Seems like a logical solution would be to only prevent the centre of the object going below ground, and disregard child prims
on a related note, tjhis might also help with your problem: SVC-742
Right, logically that would be a good solution, but that's not how the current system works. Since the havok 4 beta is all about keeping behavior the same between old-havok and new, llVolumeDetect() is the only option I have for something like this.
Yes, that feature request would help. Alternatively being able to phantom just the cone prims would help.
Ryozu Kojima made changes - 02/Oct/07 03:30 AM
Simon Linden made changes - 11/Oct/07 01:52 PM
kelly linden made changes - 11/Oct/07 02:15 PM
Fix committed internally, should be in the next beta update.
kelly linden made changes - 11/Oct/07 02:16 PM
To be clear: Physical objects with volume detect will fall through the ground.
lindenrobot made changes - 12/Oct/07 12:54 PM
I'm still not convinced on the objects falling through the ground thing, will they eventually be deleted if they fall into the ground never to return? I can think of some things that might take advantage of going underground, but if an object is below a certain allowable height (ie has fallen through the ground and end up at -256m or something) then they should be deleted after a while, say an hour. Otherwise they just use prim-count and could cause other problems.
The behavior will match what currently happens on production SL / agni. Objects that actually fall off world (go below 0 height) will be returned to lost and found.
Torley Linden made changes - 21/Dec/07 12:17 PM
Fixed in Havok4 Beta – for news & updates on the Official Linden Blog, see: » http://blog.secondlife.com/category/beta-test-grid/
Torley Linden made changes - 21/Dec/07 12:18 PM
Rob Linden made changes - 22/Dec/07 01:51 AM
Rob Linden made changes - 23/Dec/07 12:34 AM
Sue Linden made changes - 13/Nov/08 12:12 PM
Sue Linden made changes - 13/Nov/08 04:52 PM
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Bug
Closed
Normal
(Havok4) Objects with llVolumeDetect(TRUE) don't fall through ground
