Non-colony Cells getting locked to colony

I’ve had this bug happen a few times in the latest update. Sometimes in Multicellular, a cell that isn’t part of your colony gets attached to the colony, even if it isn’t touching any cell in the colony. Its movement becomes constrained to the movement of the colony. I first had this at one point immediately after leaving the editor. My stem cell spawned in as normal, and there was a fully-grown colony of my species next to me. I was struggling to move, and found that I could not swim away from the colony - I was fixed in position. When the colony moved and rotated, I was moved with it, as if my cell was part of the colony. I tried saving and reloading, and the issue didn’t return.

Later on, I found at a few points that cells which were near mine would suddenly get stuck to mine in the same way I was stuck before. I think one was a cell which had just bumped into me, but the others hadn’t touched me. I’m not sure if anything I did allowed them to get loose, but eventually they would break free and move elsewhere.

Here’s a screenshot of the initial sticking episode, and one of the late ones:

Here’s the save I first made, in case it’s useful:

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When stuck, was your cell able to rotate? I suspect that the physics bodies were overlapping and stuck due to that. If the rotation was not possible separately then this would be a much different bug. From the screenshot though it seems a bit suspicious how the colony could trap cells in it. I expect that colonies with more cells around them would be able to trap physics bodies between their individual cell bodies.

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I could rotate, but when the colony rotated, I rotated with them. The bug had actually recurred throughout my multicell playthrough. It seems to happen with any multicell organism - any nearby cell can become attached if it gets within a cell’s width of the colony.

This confirms that you didn’t become part of the colony.

This seems to confirm the physics bodies where stuck inside each other.

This is a bit strange. The only thing I can think of that is related is this:

If the bug always sticks after loading a save, I’d be very interested in getting such a save to check myself. Note that I’ll be taking away some time from Thrive over Christmas so if you provide a save soon, it’ll be a bit before I can investigate it.

The pilli hitboxes often seem to big. It does sometimes seem as though cells get stuck when the enlarged pilus hitbox collides with them. And it seems this bug occurs further away with cells near the pilus.

As for saves, the one I posted was made at the same time as the screenshot on the left. None of the erroneous attachments remain after loading.

How do you turn the physics debug draw on? I can test it more easily then.

Also, I’ve encountered a load more bugs in multicell. I was going to test with new saves to see if they’re muticellular-specific, and get more info to report on.

It’s only possible if you have the debug version of the Thrive native library as the physics engine doesn’t have debug draw capabilities when compiled in release mode. After you have that debug version of the Thrive native library you can just press F7 to toggle between physics debug levels.

I haven’t been able to find how to get the debug library. Is it on GitHub?

Also, the cell sticking issues and pilus collision issues only seem to start in multicell when the colony in the editor has more than 1 cell. I generally now go through the first session in multicellular with only the starting cell to speed it up. I haven’t noticed these issues during that session.

The native library source code is included in the Thrive repository.

You need to compile it yourself to get it (meaning you need a C++ compiler in addition to the C# development tools).

Note the -d flag needed when using the scripts to compile the native library to tell it to build the debug version.

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