Four ways to improve sim crossings with vehicles (One of them simulator side)

[Davido Chrome]

1. When a vehicle crosses a sim all the scripts needs to be transfered. Put as many functions as you can into as few scripts as possible. Use llLinkParticleSystem and llSetlinkPrimitiveParamsfast instead of making separate scritps for functions such as spinning wheels and exhaust. While it is true that scripts don't cause lag per se, each script is still assigned a time slice in each Frame Per Second of the sim, and initiating them when you enter a sim do cause lag. This lag will be reduced by limiting the number of scripts in your vehicle and that you are wearing.

2. Optimize the physics cost of your vehicle, the less surfaces that the simulator recieving you need to take into account for when you land on it's shores the better. See this post for more information.

3. Keep the prim count low, the less objects your vehicle is made of the less moving objects the sim needs to keep track off. Thus it is smarter to make vehicles from Mesh. If you use Mesh to make your vehicle you can get a lot more details into one object.

4. Simulator side, which is kind of related to 2. Make road "bridges" to make sure that the sim crossings have as few complex surfaces as possible for the vehicle to bump into after the crossing. Lower the terrain a bit under the road at the crossings so that the collision surfaces of the terrain isn't activated and align two roads made from untortured boxes perfectly with the sim border on each side. Make sure that the boxes are also aligned perfectly with eachother.

To get away from the illusion of falling into the road, and actually ending up partly inside it, link an invisble prim to the road prims on each side that overlaps four meters into the next sim. The invisible prims need to be prefectly aligned with the visible prim, and it is important that the visible prim is the root prim. And yes, this means that the invisible prims will overlap with the root prim on the other side.

OBS: Do not, under any circumstance, delink the prims until you have moved both prim into one sim or the other! ( https://jira.secondlife.com/browse/SVC-7717 )

I hope you find these tidbits usefull. /David Chrome

[Ceera Murakami]

Great suggestions, except for #4.

A 'bridge' between sims should have prims that extent 4M or more into the other sim from each side. This allows the simulators on both sides to believe there is still a surface under the person or vehicle throughout the handoff from one simulator to the other, and eliminates the necessity of having terrain just below the transition point.

In other words, in sim A there is a linkset that includes a prim that extends 4M or more into sim B. In Sim B there is a linkset that includes a prim that extends 4M or more into sim A. An example of this can be seen in the Rutgers sims "Rutgers University" and "RUCE 2" where the road between them exactly splits the sim border, with invisible prims extending across the sim edge from either side to eliminate sim crossing glitches.

[Davido Chrome]

Mind if I edit your information into the original post?

Edit: Tested and it works. I will edit it in to my post.

[Ceera Murakami]

Fine by me. The more people who know how to make good sim crossing builds, the better everyone's SL experience will be.

I've used that trick to make elevated bridges that cross from one sim to another, and to make floors for buildings on the ground or as skyboxes, where part of the building was in one sim, and part in the other. It eliminates the "falling through the floor" sim crossing issue completely.

[Davido Chrome]

Thank you!