Character doesn't stay on moving platform smaller than 5x5

I was making a platform that moves back and forth and I realized that it does not move your character along with the platform if the platform is under 5x5 size.

How it looks below 5x5:
https://gyazo.com/dbf86d1e2226b6eac1aa4f102031d4b0

How it’s supposed to look:
https://gyazo.com/4cfaeecf3b62e700221486f36d08de94

Repro file: Baseplate.rbxl (21.8 KB)

This happens 100% of the time.

4 Likes

isint that physics use some kind of circular force field ?
and the issue is the ratio between the radiance and the (distance between the center of the block and the colidable) surface ?

because, for large blocks, ive observed the inverse of this, where edges arent counted.

There are some limitations in the engine to prevent small objects, like debris from being able to move the character around as if it were a floor. If you raise the mass of this platform by changing the density you should find that it works.

7 Likes

so its the friction calculation that is having causing issues ?

Its a mix. For performance reasons the character is simulated as a floating object with forces that get applied to it and whatever its standing on (equal and opposite).

The caveat is that we prioritize user input as the most important factor, as opposed to realism. If you were to step on a bunch of loose rubble, the amount of force you can apply on a rock you step on is limited, otherwise you might send the rubble flying behind you and you wouldn’t go anywhere. In Roblox, we always make sure the force on the character is proportional to user input, but that means the equal and opposite force on the thing you are standing on might be massive if its small.

Basically without this, the force applied on the floor to keep your character afloat, or give them proper movement along the floor would send small debris flying into space. @ContextLost is working on a long-term project to make this potentially not an issue in the future, but this is how the engine works at this time, and we’re not 100% sure we’ll be able to full address this going forward (but we are going to try).

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