Terasology: Game crashes when block next to stacked fences is destroyed

[ebackhaus]

What you were trying to do

Place fence below floating fence then destroy a connected block to place another fence.

What actually happened

Game crashes when the block connected to the stacked fence is destroyed.

How to reproduce

• Place fence
• Destroy block below fence
• Place fence below floating fence
• Destroy block connected to the stacked fence

Log details and game version

v2.1.0 - Alpha 11

Computer details

Windows 10 64-bit
RAM 12 GB

[portokaliu]

I just tried this on version 78, and it seems fences break all physics in the game when you destroy a block adjacent to a fence which has an item near it.

Repro: Dig a hole in between other blocks, don't pick up the dropped block, place fence in dug out area, dig any adjacent area on the sides.

Result: No block will have a rigidbody _except_ for the block you just placed.

Observations: It does not seem to happen when the block is surrounded by only 3 other blocks on the sides. Same for destroying blocks above or below while surrounded by less than 4 blocks on the sides.

Fun fact: after destroying that block while in ghost mode, you're able to _see_ the air block (with the in-game thing that tells you block names)

[syntaxi]

@pollend could this be caused by some interactions in the Block Family code?
I suppose testing to see if any blocks using a similar family definition also break it.

[pollend]

potentially but I can't really think of a situation where this would happen. you can try using git-bisect.

[Qwertygiy]

Reproduced with a fresh build today; issue is still active.

Here is the log results upon breaking the block: https://pastebin.com/fjJsdX40
The second of the two errors is repeated every tick until the game is paused.

Once the game is exited and reloaded, physics seem to function normally once again.

[Qwertygiy]

I've discovered why this happens.

The fence cross shape (when it connects to 4 blocks) has 3 colliders.

The fence T shape (when it connects to 3 blocks) has 2 colliders.

The block entity that is interacting with the fence when it changes shape winds up looking for that third collider, which is now outside the bounds of the array.

I tested this by adding an extra collider to the T shape, and the error no longer occurred. But, of course, that isn't a proper solution.

My guess is that there is a notification event of some sort sent to the physics system when a block is broken or placed, which is not being sent when the block family chooses a new shape.

[Cervator]

Re-opening this until we can release the associated TeraBullet PR and make the engine use it - TeraBullet is fixed, but engine still needs a push to get over the finish line :-)

(Darnit GitHub, why can't you read our minds instead of our typed text?)

[Cervator]

Now properly fixed in the engine after releasing TeraBullet formally and bumping the dependency version in the engine! Thanks for the help everybody :-)