Remove items that shatter instead of dropping them intact

[Zeropol]

Summary

Bugfixes "items that shatter were not destroyed on impact. To fix #48707"

Purpose of change

Thrown glass item can display the message "the X shatters", but the item itself was still intact. Led to content duplication for say non empty bottles.
This pull request should remove the shattered item from the game, but not its content.

Describe the solution

Replaced the "drop_item.visit_items" then "add_item_or_charges" with "item( drop_item ).spill_contents;"
This way, the container should never be dropped.
I used this because it is what objects that should burst ( filled condoms ) use, and it works well for the condom.
I just copy pasted.

Describe alternatives you've considered

Also drop glass shards depending of the weight of the object.

Testing

Tests I did :

• Threw empty bottles and saw they are removed from the game when the message say they shatter
• Threw glass jars ( forgot if empty or not ) until one of them don't shatter, and saw it is not removed from the game.
• Threw filled 3L jars ( salt water ) and saw they are removed and spill their content.
• Threw filled 3L jar with multiples items ( game watch with its battery and glass shiver ) . Jar destroyed, game watch OK, glass shiv intact.
• Threw empty and filled 3L jars ( salt water ) to a chicken until it die to be sure it still work.
• used "make [..] RUNTESTS=1"
• created a test item made of glass and able to both hold a battery and liquid. Threw the item. The item shatter and is removed, the liquid drop, the battery drop.

Tests that need to be done :

• I have not identified others special cases but it would be relevant if someone comfortable with the code could verify this modification don't brake anything I did not though of ( maybe it was for a good reason that the shattered snippet did not use item.spill_contents )

Additional context

Sorry if I made someone loose its time testing a flawed PR. ( also I forgot to name and describe the commit )

[actual-nh]

Also drop glass shards depending of the weight of the object.

This should be done, but perhaps wait for this part until after the problem with slowdowns from lots of objects (#47007 and others) is (mostly?) fixed?

[Zeropol]

If it is relevant I'll consider it then, thanks for the indication ! ( except if someone do it of course )

The slowdown caused by thousands of glass shards is maybe mostly caused by broken windows in cities, while the players ( I think ) usually don't throw molotovs/glass items every minute so it should not contribute that much to the glass shard abundance. ( while still be useful for "innawood" character who need a few shards ).

If I do it I propose to submit it in a different PR so if it can hurt performance it is easier to sort ( I suppose ).

[Zeropol]

In regard to make shattered item drop shards, I ran into the problem that the function that return the mass of an item is only partially implemented.

Cataclysm-DDA/src/item.h

Line 569 in b991a1b

units::mass weight( bool include_contents = true, bool integral = false ) const;

The parameter include_contents is not used.

As a consequence, filled glass containers would drop more shards than the same container when empty.

I also noticed some values I question :

• 3L jar have density of 93 kg/m³, its mass of 0.36 kg disassemble into 5 shards.
• jar have density of 220 kg/m³, its mass of 0.15 kg disassemble into 2 shards.
• bottle have density of 341 kg/m³, its mass of 0.45 kg disassemble into 3 shards.

As a result, shattered 3L jar would drop less shards than a bottle.
( instinctively, 3L jar could be heavier, or bottle could disassemble into more shards )

Would it make sense to determine the number of shards based on the volume instead of the mass ? I'm not seeing what side effect it could cause, if it do.
( looks like units::volume volume( bool integral = false, bool ignore_contents = false ) const; is fully implemented )

If this question is out of scope for this particular PR, please tell me so I ask for insights in the Discord instead of here.
Thanks :)

[Alex-Folts]

In regard to make shattered item drop shards, I ran into the problem that the function that return the mass of an item is only partially implemented.

Cataclysm-DDA/src/item.h

Line 569 in b991a1b

units::mass weight( bool include_contents = true, bool integral = false ) const;

The parameter include_contents is not used.

I guess you should use this method, but create new issue about this method is not fully implemented so it would be resolved as separate PR.

[Zeropol]

Thanks you for the insight Alex-Folts !

I also thought of using the itype instead of the actual item ( the mass should always the mass of the empty object with this method I hope ), I will try, but before I'll follow your advice and create an issue.
edit : I had it working :D and will submit the PR later today

[Alex-Folts]

Also some time ago was related to glass shards PR: #42212
with this technically you can craft galss shards from glass objects, but smashing glass object against wall to make glass shards sounds more natural.