bw pathfinding being what it is, put the spider mine on unwalkable terrain the moment it got in range also slightly worth noting that this walkability test is buildtile/megatile resolution, so effectively it checks if more than 12 minitiles within that are are walkable in that regard, the bw pathfinding might not be doing anything wrong here, it's just a resolution issue with the walkability test.
To add some more background to that:
Each terrain tile is made up of 4×4 minitiles, which are either walkable or unwalkable.
At game-start the game classifies each tile with at least 4 unwalkable minitiles as unwalkable, all other tiles as walkable.
Whether a ground unit can occupy a location depends solely on the minitile walkability property.
The tile the mine from the clip detonates on has 8/16 unwalkable minitiles and is thus classified as an unwalkable tile, which makes the Mine dud out.
Conclusion: Near unwalkable terrain, such as cliff edges, in particularlyin tight chokes, or doodads, there is a certain chance that Mine damage will be completely mitigated.
EDIT: Here's the whole situation recreated in ScmDraft with overlays showing the relevant walkabily properties: + Show Spoiler [Show animation] +
EDIT2: Thanks to StaticNine for another video demonstrating the effect. Note that the video title does not explain the conditions and cause of the effect correctly: + Show Spoiler [show video] +
On February 22 2021 12:22 FlaShFTW wrote: I love how this one clip is getting so much traction. My goon is a hero now, and his tale will be echoed throughout Auir.
Wait till Bisu finds out – and perfects his cliff-hugging technique
The red is unwalkable tiles. As I explained where stuff can go is determined on the minitile level, which is the grey overlay. As far as this topic is concerned: Grey prohibits movement, red makes Mines dud.
Just one quick question: What exactly do you mean by "grey prohibits movement"?
From your explanation above - 'ground units can occupy walkable mini-tiles' - I had the impression that units can walk/move on walkable mini-tiles, despite the whole tile being classified as unwalkable. Maybe only by patch-finding accident, but isn't that what the mine in the video did, no?
Or did you mean: "Normally units won't step on walkable mini-tiles if the whole tile is unwalkable"? Are units being pushed off of a walkable mini-tile (in an unwalkable whole-tile) should they accidentally move onto it?
Units can occupy any walkable space they can fit in. But if the tile is flagged unwalkable any mine explosions on it will be duds. The mine can move onto the tile because it is partly walkable (has walkable minitiles), but doesn't deal damage because the whole tile is flagged as unwalkable.
Or, to be very technical about it:
A ground unit's collision box may not overlap with any unwalkable minitiles
If a ground unit overlaps with unwalkable terrain it will be force-moved to the "nearest" (according to the game's idea of nearest…) walkable area (this just as a side note, it is not relevant for the effect discussed in this thread).
The centre of the collision box (rounded up coordinates) is the actual unit position, which is what is checked to determine the terrain flag checks for the unit.
Maybe it's not quite clear what I mean with grey, because the grey overlay actually looks dark red under the red overlay… Can you see that there are two overlays visible on that image, the darker one with 4× the resolution of the other? Maybe I should make a gif…
So there are mini-tiles that are either walkable or unwalkable, but a tile as a whole is either flagged as walkable or unwalkable? Are there any other circumstance where a whole tile being flagged walkable or unwalkable matters? Other than building placment presumably. Scarab duds too due to this perhaps?
I guess with this info the best way to make a spider mine dud is make it hit a unit on the sides of a ramp or throw your unit to a corner and hope for the best.
On February 24 2021 05:13 Dangermousecatdog wrote: So there are mini-tiles that are either walkable or unwalkable, but a tile as a whole is either flagged as walkable or unwalkable? Are there any other circumstance where a whole tile being flagged walkable or unwalkable matters? Other than building placment presumably.
Pathfinding regions are generated and connected based on the walkability and terrain level tile flags (both generated from the respective minitile flags at game-start), so indirectly they have a huge bearing on long-range pathfinding and a plethora of associated behaviours.
Buildability is only determined by the buildability flag, a game-generated "partially walkable" flag (which is set as soon as one minitile of a tile in unwlkable) and a creep flag for Zerg (there are some special cases regarding partially unwalkable, but buildable tiles). Creep spread is only determined by the buildability flag though (and has some unintended buggy interaction with a deprecated "flipped doodad sprite" flag).
Scarab duds too due to this perhaps?
Read the quote from the OP, follow the references! The relevant flag check is specifically hardcoded for Mines only. Scarabs dud due to timeout, when they cannot reach their target due to other units blocking the way, or when the Reaver owner aborts the attack (gives the Reaver a stop order).
I guess with this info the best way to make a spider mine dud is make it hit a unit on the sides of a ramp or throw your unit to a corner and hope for the best.
Something like this. In practice it is situationally useful to know and somewhat luck based, I guess.
Only very indirectly. The reason for Reaver jams is a bad pathfinding region layout. Because Scarabs are ground units Reavers use pathfinding distances instead of normal distances to determine their attack range. Pahfinding distances across three or more regions are measured over the nodes of the intervening regions, so if the nodes are far off the shortest path the effective attack distance will be severely shortened.
Interesting. Also, there a bunch of doodad's that give 100% invulnerability to spider man damage if the spidermine approaches from the south. Here is a video showing it:
It's not the direction of approach though but of where the Mines explode, right next to the doodad where tiles are flagged as unwalkable. If you flipped Marine and Mine positions in this setup you'd get the same result.
But it's a nice, instructive video. I'll link it in the OP.
EPT![[image loading]](https://i.imgur.com/Kc2Ch4d.gif)
![[image loading]](https://i.imgur.com/CntSh36.jpg)
