Physics model - user defined?

[Reid Parkin]

I've been using physics model user defined recently instead of the one triangle I usually use for phantom objects. It seems to work well in keeping LI low, just as well as a single triangle, and easier since it's right there to select.

My question is what is it exactly? What does user defined mean?

[arton Rotaru]

That's a Firestorm feature as well. If the default shapes aren't good enough for your likings, you can add your own physics mesh to the list of default shapes. This will be used when you select User Defined then. This can be added under the Settings tab of the uploader I guess.

For properly fitting physics meshes, you would still want to use the From file option, though.

Edited October 30, 2021 by arton Rotaru

[Aquila Kytori]

Earlier in the year the Firestorm Devs made some improvements to the mesh uploader and one of them was adding 3 new options when selecting which Physics shape to use.

From Beq's techy blog :  https://beqsother.blogspot.com/2021/06/summarising-next-improvements-to.html

" As of the next Firestorm release, creators will find 3 new options when selecting a physics shape.

1) The cube.

2) The hexagonal cylinder.

3) the user-defined mesh. "

 

User-defined means that if for some reason or other you often find yourself needing the same basic Physics shape for different models you can now have this same particular custom shape readily available as an option in the mesh uploader.

 

 

For example, lets say you like to use a triangle based pyramid shape for many of your projects :

 

1: Create the triangle base pyramid model and save it as a .dae file somewhere on your hard-drive.

2: Next time you open the SL mesh uploader go to the Preview settings options and paste in the location of the tri_ pyramid_Phys.dae file.

3: Open the Physics tab and now whenever you choose the User Defined option the triangle based physics shape will be automatically loaded as your physics model.

 

 

10 hours ago, Reid Parkin said:

I've been using physics model user defined recently instead of the one triangle I usually use for phantom objects. It seems to work well in keeping LI low, just as well as a single triangle, and easier since it's right there to select.

Choosing to use the  User Defined option and not having it linked a .dae file on your hard-drive will be the same as leaving the "Pick a physics model" field blank. The Physics cost then varies from model to model (depending on complexity ?). And in the Features tab of the inworld Build floater > Physics Shape Type, you wont have the Prim option. 

 

 

 

Edited October 30, 2021 by Aquila Kytori

[Aquila Kytori]

Arton again got there first lol

and notes something important :

2 minutes ago, arton Rotaru said:

For properly fitting physics meshes, you would still want to use the From file option, though.

 

[arton Rotaru]

1 minute ago, Aquila Kytori said:

Arton again got there first lol

Easy, when only typing out the bare minimum, instead of such a comprehensive reply like yours. 😇

[Chic Aeon]

I was SO happy to see both cube and hexagon cylinder added. Much easier than looking up my homemade ones over and over and over :D.  

[Beq Janus]

On 10/30/2021 at 2:58 PM, Chic Aeon said:

I was SO happy to see both cube and hexagon cylinder added. Much easier than looking up my homemade ones over and over and over :D.  

We share our laziness 🙂

I had a long debate (with myself, it gets that way sometimes) over including the "user defined" worrying that the risk of additional confusion was likely higher than the number of people who'd actually use it. Now that it is out there I wonder what the general consensus is? Worthwhile option or confusing distraction.

[Reid Parkin]

I'll find it very useful, so thank you, Beq, for including 'user defined'.

I've now followed Aquila's detailed instructions, thank you for adding all the detail. The bare minimum wouldn't work for me.

I think most people who use phantom objects such as plants would use a single triangle almost all the time.

[Chic Aeon]

I am not really seeing any use for myself of "user defined".  I either use a cube or a hexagon cylinder OR make a "correct"  physics model when needed. so  I will likely just keep ignoring that option LOL.   But if it is helpful for some folks then that is great. 

[LittleMe Jewell]

3 hours ago, Beq Janus said:

I had a long debate (with myself, it gets that way sometimes) over including the "user defined" worrying that the risk of additional confusion was likely higher than the number of people who'd actually use it. Now that it is out there I wonder what the general consensus is? Worthwhile option or confusing distraction.

I almost always use either a cube or a triangle for the simple stuff. Since the cube is now an option to select, but a triangle isn't, it is nice that I can define my triangle and have it available as an easy default also.

[Aquila Kytori]

10 hours ago, Beq Janus said:

I had a long debate (with myself, it gets that way sometimes) over including the "user defined" worrying that the risk of additional confusion was likely higher than the number of people who'd actually use it. Now that it is out there I wonder what the general consensus is? Worthwhile option or confusing distraction

Confusing? yes but worth keeping.

My two cents :

First thoughts were "What's the difference between From File and User Defined. Surely they are the same thing?"

Also having them one above the other at the bottom of the list doesn't help.

Perhaps have Load from file (instead of From File, as this would be consistent with the wording used when choosing the Source of the LoD models in the Level of detail tab) at the top of the list.

Does anyone use the High, Medium, Low or Lowest options especially now there are the new ones?  If yes aren't those covered with Load from file ?

So with the LoD options removed next would be Triangle because that seems to be a popular choice to have, followed by Cube and Hexagonal Cylinder. (Cylinder added because that's what it is, less confusion).

And finally User pre-defined instead of User defined. 

At the moment when hovering your mouse over any one of the options it displays the same "LOD to use for physics shape" in the info field. Perhaps you could make use of this information field to show a link to the relevant Beq's tech blog page or have a few words describing what it is ?

And why is Choose one . . .  shown twice ?

 

Edited November 1, 2021 by Aquila Kytori

[Beq Janus]

All good input thankyou. I'll try to take this into account when I am next poking at the uploader.

One question though

21 hours ago, Aquila Kytori said:

So with the LoD options removed next would be Triangle because that seems to be a popular choice to have, followed by Cube and Hexagonal Cylinder. (Cylinder added because that's what it is, less confusion)

Why would anyone want triangle?

I am confused as to why this is (apparently) popular as it appears to me to have no value. Indeed, it serves only to make problems.

1) It stores up problems in terms of raycasting and collision detection.
2) you are effectively adding a "useless" physics, when you might as well just leave it untouched and keep just the default convex hull.
3) It makes Beq sad.

Is there a use case I am missing where the triangle is an important and valid option?

[ChinRey]

2 hours ago, Beq Janus said:

Why would anyone want triangle?

The single triangle has the lowest physics weight among the shapes available to meshes and it is of course the less intrusive option. So I used to recommend it as the physic "zero model" for phantom objects to minimze the damage if they were accidentally switched from physics shape none to prim/convex hull in-world. It's hardly a big deal though and we don't want to make Beq sad of course.

Edited November 2, 2021 by ChinRey

[Aquila Kytori]

4 hours ago, Beq Janus said:

2) you are effectively adding a "useless" physics, when you might as well just leave it untouched and keep just the default convex hull.

The Default, (leaving the option blank) if I remember correctly uses the LOW Lod model for Physics. If this low LoD is relatively complex (think smaller objects) then the Physics cost can be alot higher than the download cost.

Example of a  small plant,  (see the build floater for the custom LoD tri counts).

Default Physics model (nothing selected) the Physics cost dominates the download cost Download = 0.236     Physics = 3.480      Land impact = 3.480.

 

and when rezzed :

 

Same LoD models but this time using a single triangle for Physics :

The physics cost is under control. Download = 0.236   Physics = 0.200   Land Impact 0.500.

 

When rezzed  and Physics shape type is Convex hull or Prim the Physics weight remains at 0.2

 

2 hours ago, ChinRey said:

It's hardly a big deal though and we don't want to make Beq sad of course.

Agreed

Lets forget the triangle idea ...............                                                                   . (but leave the User defined option.......................... )

 

[ChinRey]

17 minutes ago, Aquila Kytori said:

The Default, (leaving the option blank) if I remember correctly uses the LOW Lod model for Physics. If this low LoD is relatively complex (think smaller objects) then the Physics cost can be alot higher than the download cost.

You are right of course but I assumed and still assume that it was just a slip Beq made when she wrote the post. Choosing a cube rather than a triangle for a phantom object will never affect neither the land impact nor the actual physics weight as long as the object stays phantom.

However, that brings up another issue, what is the point of that "Choose on..." default option on the menu at all? I can't think of a single use for it, nor can I remember to have ever seen it in any other drop menus of any kind. How about removing it and maybe make the cube the default since it seems to be by far the most commonly aproproate option?

[Beq Janus]

On 11/3/2021 at 1:47 AM, ChinRey said:

You are right of course but I assumed and still assume that it was just a slip Beq made when she wrote the post. Choosing a cube rather than a triangle for a phantom object will never affect neither the land impact nor the actual physics weight as long as the object stays phantom.

However, that brings up another issue, what is the point of that "Choose on..." default option on the menu at all? I can't think of a single use for it, nor can I remember to have ever seen it in any other drop menus of any kind. How about removing it and maybe make the cube the default since it seems to be by far the most commonly aproproate option?

And yeah, it was my slip. I even thought about it! I typed low then (incorrectly) corrected myself at the time.

Thank you Rey and @Aquila Kytori for the examples, and I agree that that usage is valid, I am still reticent to include it because people would go "oooh tiny weeny phsyics, yes" and use it for all the inappropriate things where a cube would by a far better choice. Ultimately we can't stop stupidity but I try to avoid handing out free passes too. I'll revisit this once we get a little closer to being allowed to merge in the mesh optimiser branch that LL have. I'll be looking at that once I have my avatar render time and "auto tune" features mature enough.