[Crash] Warcraft III: Desync on Bridges Due to Vision Processing

[Makkad]

The video shows that as the bear descends the slope, a skeleton positioned in the upper right part of the slope remains visible for one player but goes out of sight for another. When an attack command is issued on the skeleton, this vision discrepancy causes the game clients to desynchronize.



This bug occurs on Warcraft III version 1.26. I was unable to reproduce it on Warcraft III: Reforged, but I can’t be certain the issue is completely absent there.

The issue seems related to vision processing rather than any triggers or modifications of Z-coordinates through the editor. Removing Fog of War on the map prevents the desync, as it ensures both players share the same view. Bug could be caused by different type of bridges, not only slopes.

This bug is relatively rare, and reproducing it consistently took considerable effort. However, it does occasionally occur and disrupt gameplay. I also found an old post describing a similar issue related to bridges and vision, which is unrelated to triggers: [Link to discussion].

I’m looking for guidance on resolving this issue without having to remove bridges from the map.

- Could adjusting object fields like Fog Radius, fatLOS, and occH in the editor help reduce the likelihood of desync? Any recommendations on configuring these fields would be helpful.

- If I add additional vision using the CreateFogModifierRect() function, are there any key considerations?

Any insights or ideas for avoiding this error (except removing bridges) or helping with custom vision system, when units enter into region near bridges would be very appreciated. Thank you!

 

[Tal'Rarity]

Problem is from vision, though what causes the d/c state is because of the bear issuing an order about to attack the skeleton not really visible.

The solution for stuff like this usually was solved by reconnection, can either try fixing the bridge closer to the cliff/terrain or lots of invisible platforms to mimic bridges while turning off model generating walkable status or a visibility check and quickly use some way of vision for all players that should see this player. Probably more idea's, but further along it gets more and more complicated like showing units through fog or turning off the lighting to make your own real vision while keeping map revealed.

 

[SpasMaster]

I've encountered this many years ago (~2013) on multiple occasions and remember reading in a few forums that bridges cause it, though at the time no one had specified the exact reason for it - it might have even been the one you linked. Now that you explain this in detail, it starts to make sense.

I want to add to this by saying that I've also encountered this with other doodads that affect vision over the years like Elevators and Ramps.