How do I build a walkable surface across a Region border?

[BJoyful]

One of my favourite things to do in SL is watch Regions disappear and reappear on Restart Tuesdays.  I'm not sure why 🤔 but the shock of everything gone 😯 and the satisfaction of seeing it reappear is so gratifying 🤩

We acquired a small parcel in an adjacent Region as a retreat just so we could enjoy the restarts on Tuesdays...

We've decided to give our parcels a more realistic makeover in the spirit of Three Cliffs Bay in Wales.  We currently experience falling through mesh only when walking east (to the right in the photo above) and see if anyone can help with this common Mainland Region Crossing issue, being... falling through mesh while walking across when the actual land is several metres below the mesh we wish to walk on.

I have noticed on other builds that terraforming the land up to just beneath the mesh works very well... but this land is in a +/- 4m from default area and +4 m falls short of the mesh at water level.  I've also noticed that walking slow with a pause on or close to the crossing helps prevent falling through... but its easy to forget when the countdown to restart is ticking away!

We look forward to experimenting and hope someone can provide a suggestion or a solution.  Thanks for reading my Topic ♥

 

[Candide LeMay]

The surfaces you walk on have extend past the sim border for about a meter or two. You have to build sort of an overlapping bridge. Invisible prims work fine for this if you just want to fix the physics. Do this from both sides of the sim border  (prim1 is rezzed in sim1 and extends into sim2, prim2 is rezzed in sim2 and extends into sim1. prim1 and prim2 partially overlap) and you should be able to walk back and forth without falling down.

[Diablo Lioncourt]

Just a little physics layer of an invisible prim rooted on each side extending onto the other a few should do

[Aethelwine]

There is a bit of art to it. On each side you need a prim that extends about one third its length across into the neighbouring region. So say you take a 6m prim push it two meters into next region and then in the adjacent region have another 6m prim extending 2m back into the other prim. you can make them invisible so you don't get glitching textures. Then test it and if it doesn't work try something a bit bigger and minor tweaks but I think that should work. It has been quite a few years since I was building roads across region boundaries.

Edited December 21, 2023 by Aethelwine

[Abnor Mole]

There are a few ways to handle region crossings. One is to bring up the land to just underneath where you are walking. You will fall through, just only until you reach the terrain underneath.

The reason this happens is the physics of an object do not extend into neighboring regions. When you cross a region border there are always at least a few fractions of a second while your avatar is traveling from one simulator to another. In that time if your position goes beyond the physics bounding box of an object you will enter that simulator inside, under, or past that object. Try it with a vertical wall on a region border and you will pass right through the wall when coming into the region.

In the case of walkable surfaces much depends on the object itself and its physics shape. If the physics are very thin on the surface and/or hollow you can easily end up underneath or trapped inside after crossing. What you need is physics shapes supporting your avatar on both sides of the crossing that compliment each other.

For flat surfaces an invisible prim box works just fine. Extend them across the border in both directions so they overlap at least a few meters. For best results make sure the prim is thick enough so if your avatar dips down into it slightly during the crossing it pushes you up and out of it instead of down and under. Also, objects where the physics of the root of a linkset (or an unlinked single object) tend to work slightly better than if it is the physics of a child link. It is more important that the physics of both objects occupy the same physics area at the crossing at least for a few meters. This method works fine for roads or any flat surface that crosses the border.

But what about complex physics shapes like a rock outcropping? For this there is another trick you can do. Assuming the object is modifiable, rez a prim cube next to it in the same region the rock occupies. Drag copy another copy of the rock upward and use ctrl-z to snap it back to the same position as the original. Link that rock to the cube you rezzed making the cube the root. Now change the opacity so the entire linkset is invisible. Once you have done that,  edit ONLY the root using Edit Linked and move it across the border into the other region and hide it underground or inside something so you won't bump into it when walking. Now you have two objects with the exact same physics shape on both sides of the border.

 

Edited December 21, 2023 by Abnor Mole

[BJoyful]

3 hours ago, Abnor Mole said:

But what about complex physics shapes like a rock outcropping? For this there is another trick you can do. Assuming the object is modifiable, rez a prim cube next to it in the same region the rock occupies. Drag copy another copy of the rock upward and use ctrl-z to snap it back to the same position as the original. Link that rock to the cube you rezzed making the cube the root. Now change the opacity so the entire linkset is invisible. Once you have done that,  edit ONLY the root using Edit Linked and move it across the border into the other region and hide it underground or inside something so you won't bump into it when walking. Now you have two objects with the exact same physics shape on both sides of the border.

I used a sort of combination of @Candide LeMay, @Aethelwine and Abnor's suggestions... making an invisible copy of the rocks and linking the visible rocks to a prim just below the mesh on one side and the invisible rocks copy to a root in the other Region.  I then edited the root on each side to overlap the Region border and it works perfectly!   (Before and after gifs below)

This works brilliantly!!  Abnor, you are so clever!  This is never something I would have thought to try but I completely understand why it works and is a great example of why its so educational and fun to watch Moles at work in SL!  We never know what tips and tricks we'll learn if we understand what they're doing! 🤩

BEFORE gif...

AFTER gif...

Thank you all for your help and advice! ♥♥♥  WoOOOhOOOo!  No more wet feet from falling through mesh!!   Problem SOLVED ♥

Edited December 21, 2023 by BJoyful

[rasterscan]

You never got wet feet. You made me get wet feet 🤐