As a Roblox Developer specializing in cars & racing in a competitive nature, due to what the community calls “Vision Lag.” After sitting down with someone from the physics team at RDC, I really like what they had to say about fixing the issue, until they hit the catch. They said without anyone pushing on the DevForum for a change to this, it’d never happen, so, here I am. Here is my Feature Request.
So, to start off, the problem. Vision Lag. Vision Lag occurs when a client sends their position to the server and then to other clients slower than what they visually see their position at. Because of this you get weird issues where the view from two racers & a spectator are 3 wildly different views. I made a video to help understand the problem.
When Analyzing some screenshots from the video, you can see just how bad it is:
In this photo, at the start of the race, the Orange car sees the Orange & Pink car even, whereas the Pink car sees themself way out front. Even more out front than what the spectator sees.
Now as we get to the corner, each car sees themselves out in front, whereas the spectator sees them dead even. This causes issues where cars are able to drive inside one another from a spectator view, because neither car see their opponent in that spot they actually are. Because of that there is a lot of issues dictating what position you ever actually are in when the racing is side by side and close. Also, this makes car to car contact extremely difficult as neither car actually sees their opponent in the right place. Most collision causes in weird glitching.
So, what is my proposed solution. After talking with someone from Physics, their suggestion was a system similar to GTA V with simulated positioning. Apparently in GTA V, the server places the cars slightly ahead of their actual location to help decrease the issues with latency, and because of that certain glitches appear at high difference of speed things, however for low difference of speed issues like car to car bumping and rubbing, it works really well. (Playing chicken is still glitchy, but it’s not the intended thing for racing anyways.) Predicted Simulated Positioning would change the world of racing on Roblox.