Fix projectile interaction with obstacles; remove ACID_DROP from documentation #17759

sethsimon · 2016-07-21T01:13:52Z

Non-bullet projectiles will only penetrate an impassable obstacle if it destroys the obstacle and still has momentum afterwards (e.g. throwing axe vs. window). Bullet projectiles (those that deal DT_CUT and have a high speed) will penetrate an impassable obstacle whether it destroys the obstacle or not, as long as it has momentum after hitting it.

Also, it's a little odd that the acid that corrosives spit disappears if it hits the ground (and not a creature). I noticed that there is a documented ammo effect in doc/JSON_FLAGS.md called ACID_DROP that "creates a tiny field of weak acid." Strangely, it wasn't implemented, so I implemented it and added it to the projectile created by mattack::acid_accurate.

This has the effect of buffing corrosives a bit. In testing, it appears that if you leave the field as soon as it appears under your feet, the field will cause about 10 damage if you have no clothes on your legs or feet, or 5 damage when wearing socks/boots and briefs/cargo pants.

Now that the projectile's speed is a determining factor in deciding whether it's a bullet or not, throwing axes can't go through dressers anymore.

pisskop · 2016-07-21T02:58:38Z

im not sure coorosives spit enough acid to make a puddle.

in fact, im sure it was removed because its annoying unavoidable damage and encourages minmaxing.

corrosive acid doesnt puddle when it hits a player, unless thats been readded very recently
corrosive acid burns the players via damage over time if it hits, targetted. the puddle is redundant

sethsimon · 2016-07-21T03:57:14Z

You're right, it was removed in #14775.

Coolthulhu · 2016-07-21T10:01:26Z

src/ranged.cpp

+                           proj_arg.impact.damage_units.end(),
+                           []( const damage_unit &dam )
+    {
+        return dam.type == DT_CUT;


This will make thrown rocks stop at windows.

IRL, a rock that's badly aimed, weakly thrown, or thrown from far away might not go through a window. With 2 throwing, 5 strength, 5 dexterity, and from 1 tile away, 4 out of 14 throws broke a window. With 2 throwing, 8 strength, and 8 dexterity, you can reliably break it from 3 tiles away. With 0 throwing, 8 strength, and 8 dexterity, you can reliably break a window from 2 tiles away. With 1 throwing, 5 strength, and 5 dexterity, it's very difficult (but possible) to break a window from 1 tile away.

EDIT: All the tests had 7-8 perception.

This check gates whether or not a projectile could go through furniture or terrain. It's gating by speed, obviously, but also by damage type. But, why? This commit fixes a problem where you could not shoot through fences. This problem has also appeared in the past, and in both instances, it was because of this damage type check. So, clearly this damage type check does something, but does it do what it's supposed to? Going back to the commit that introduced it, a037977, it shows that it was introduced because the author or that commit though it was the only way to tell if a projectile was a bullet or not. In the commit after next, the author also adds the projectile speed check. Going to the PR that commit is included in, CleverRaven#17759, it reveals that this was likely introduced to prevent corrosive zombies from using their acid spit over things like dressers and through things like chain link fences. And indeed, removing this allows them to spit through these furnitures, but more importantly, through reinforced vehicle glass. So, let's use an ammo effect instead to determine if it should penetrate obstacles or not.

sethsimon added 5 commits July 19, 2016 21:55

Only let bullets go through impassable stuff

a037977

Implement ACID_DROP and use it in the acid_accurate attack

4608c2f

Modify is it a bullet? determination

7cc899d

Now that the projectile's speed is a determining factor in deciding whether it's a bullet or not, throwing axes can't go through dressers anymore.

Check the cheaper condition first

f1fe238

Indent properly to appease Jenkins

e37cee1

Remove ACID_DROP from corrosives

74bf00e

Coolthulhu reviewed Jul 21, 2016
View reviewed changes

sethsimon changed the title ~~Fix projectile interaction with obstacles; give corrosives ACID_DROP~~ Fix projectile interaction with obstacles; remove ACID_DROP from documentation Jul 21, 2016

Remove documentation and implementation of ACID_DROP

85e82b9

Coolthulhu self-assigned this Jul 25, 2016

Coolthulhu merged commit 24d829b into CleverRaven:master Jul 25, 2016

sethsimon deleted the corrosive branch August 4, 2016 19:53

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Fix projectile interaction with obstacles; remove ACID_DROP from documentation #17759

Fix projectile interaction with obstacles; remove ACID_DROP from documentation #17759

sethsimon commented Jul 21, 2016

pisskop commented Jul 21, 2016 •

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sethsimon commented Jul 21, 2016

Coolthulhu Jul 21, 2016

sethsimon Jul 21, 2016 •

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Fix projectile interaction with obstacles; remove ACID_DROP from documentation #17759

Fix projectile interaction with obstacles; remove ACID_DROP from documentation #17759

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sethsimon commented Jul 21, 2016

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