EPTOn November 05 2017 23:12 Freakling wrote:+ Show Spoiler +
Well, there's nothing new about this. From the comments it seems like half the people in this thread still have not completely understood it yet, though, maybe because of the somewhat crude translation in the subtitles.
What is miss chance?
Miss chance only applies to ranged, direct impact attacks (from both air and ground units) and has the following effects:
When does miss chance apply?
Useful notes:
Well, there's nothing new about this. From the comments it seems like half the people in this thread still have not completely understood it yet, though, maybe because of the somewhat crude translation in the subtitles.
What is miss chance?
Miss chance only applies to ranged, direct impact attacks (from both air and ground units) and has the following effects:
- The point of impact of the attack is moved
one tile30px (according to OpenBW code) towards the attacker. - All direct damage is nullified. Splash damage still applies, but around the actual point of impact.
When does miss chance apply?
- There is always a miss chance of 1/256 (.390625%).
- Ground units on lower ground have a 120/256 (46.875%) chance to miss ground units on higher ground. Air units are not affected, neither when attacking nor when being attacked (but can still profit from the vision blocking effect that higher ground gives).
+ Show Spoiler [some technical details] +There are three terrain levels in Brood War: low, medium and high ground. These are determined by minitile flags (small areas of 8x8 pixels). A unit's terrain level is determined by the flag of the minitile at its exact position, below the centre point of its collision box, coordinates rounded up to full pixels. Miss chance is the same from low to medium, low to high and medium to high ground. - There is a tile flag that causes a miss chance (known as cover effect) for units positioned on certain doodads/doodad tiles. This miss chance is also 120/256 (46.875%) and effects both air and ground attackers, independent of their terrain level. There is no stacking effect with high ground miss chance.
+ Show Spoiler [some technical details] +Units do not actually have to be positioned visibly behind the doodad sprite, in fact for most doodads this will have no effect at all, except for visibly obscuring the unit. To gain cover they need to be placed on one of the doodad tiles.
A tile is a basic terrain block of 32x32 pixels. Unit position is determined as below the centre point of its collision box, coordinates rounded up to full pixels.
Cover providing doodads roughly encompass the following :- tree doodads in Badlands
- tree doodads in Jungle
- most of the hut doodads in Desert as well as most of the bulkier plant doodads and the big derelict CC and derelict factory doodads.
- the more bulky building on snow doodads in Ice.
- none of the doodads in any other tileset provide cover.
- tree doodads in Badlands
- Dark Swarm grants a 100% miss chance for units under it, effecting both air ans ground attackers. Unlike the other sources of miss chance, Dark Swarm does not apply to buildings.+ Show Spoiler [some technical details] +Again, what determines whether a unit is considered under Dark Swarm cover is not any kind of overlap of the visible sprites but whether the unit's collision box overlaps the Dark Swarm's one, which is a square of 160x160 pixels.
- Different sources of miss chance do not stack up. Only the highest miss chance applying to any particular source of damage will be applied
Useful notes:
- melee attacks are not affected
- pure splash attacks (no point of impact) are also entirely unaffected. this is why the linear splash attacks of Lurkers and Firebats as well as the suicide splash attacks of Scarabs, Spider Mines and Infested Terrans still fully apply.
- For bouncing shots (Mutalisk) miss chance is only evaluated for the first hit. If the original attack misses, the shot will not bounce, but when it hits, the bounces will also hit their targets with 100% chance, disregarding any miss chance.
- miss chance has no effects on spells.
- burrow negates partial splash. To damage burrowed units they need to be within the 100% splash radius of a radial splash attack, which is why they can still be killed with indirect shots, but need to be hit directly at the point of impact.
- It is actually pretty easy to accurately predict where the point of impact of missed shots will be. It is moved by about 1 tile (30 pixels) towards the attacker along a straight connection. Since 32x32 pixels is the collision size of most big units, such as Lurkers, Dragoons, Reavers, Archons or Factory units, if a tight group of such units is targeted, shots missing a unit in the back will fully hit the row of units in front of it.
- Missed shots of sieged Tanks will land inside its minimal attack range of 2 tiles (64 pixels), but still not close enough to damage the tank itself.
I actually didn't know this. I just thought the miss chance just made the attack do zero damage.
