[PATCH] Capturing Buildings

[historic_bruno]

This should fit in nicely with our new territories implementation and proposed unit conversion. Currently all units can attack structures, but this will change so that only siege units destroy buildings while capturing will replace their attacking behavior. Some outdated info from the design doc:

• Longest capture time
• Small capture radius
• No capture if enemy already has ownership and is within one of their unit's LOS
• Cannot capture if garrisoned
• Cannot capture if hitpoints are not reduced to a specified percentage
• Capturing an enemy structure changes the ownership of a structure from the previous owner to the new owner. It does not allow the player to research another civilisation's technologies or train units that are unavailable to the player's civilisation. However the visual structure remains the same.

[wraitii]

11 months later, this seems like the last big remaining gameplay stuff to add.

I think capturing should be done with a mechanism like "reverse garrisonning". Your units enter an empty building, and it slowly gets captured (perhaps with a resistance factor that slowly kills your units inside. Low for houses, huge for fortresses).

I don't like the fact that buildings couldn't be captured if in the LOS of another unit, or above a certain HP level, which is why I think the "garrisoning" system is a more convenient, more realistic, and better way.

[Erik Johansson]

Hmm, how would that be countered? I mean if the units are outside the building when they are capturing it the enemy can always try and kill them off before the building is captured, but if they are inside it, what way is there for a player to affect the outcome?

I do agree that the LOS/hitpoints limits should probably be removed, they make more sense for other things like animals/female citizens in the first case, and ships in the latter (though it's been decided not to include ship capturing for now, but in concept I mean). It might make sense to make it easier to capture a building with fewer hitpoints though, but I'd say that depends on how much that complicates implementation.

[wraitii]

I'd assume it would be countered by garrisoning (so attacking units would not necessarily have to attack an empty building... But may not be able to enter all buildings above a certain HP threshold. Basically houses would be open at 95% HP (tore the door down), fortresses much lower, and then there'd be a fight (and garrisoned units would be a bonus to the "base resistance level" which would slowly kill units (to simulate units inside).

[historic_bruno]

Hmm I'd rather see and be able to fight the capturing units. If everything happens hidden inside the building, that's kinda lame. Even though it might be "realistic" that units have to go inside structures to capture them, it feels less exciting for gameplay. Like I'm going to be watching UI status instead of controlling units.

[wraitii]

The capturing units would just stand out there like they're doing now for destroying then? What would the animation be? I'm not really seeing how this could feel right (though I agree, it'd be nice to see stuff).

[Erik Johansson]

It's how it's done in Empire Earth (though since their infantry can destroy buildings as well you have to choose specifically to capture rather than destroy the building), the units display something like the healing animation we have now while the building is being captured. In EE only infantry can capture buildings, and that might be something we may or may not want to do. After all, if we're only giving cavalry the ability to capture female citizens it would make sense to only give infantry the ability to capture buildings, to differentiate their roles a bit more. Cavalry would still be useful in building capturing situations as they could defend the capturing units.

[historic_bruno]

Maybe start a topic for it on the forums, that way everyone can view the ideas and give suggestions.

[sanderd17]

A patch added for capturing buildings. There are still some problems and questions remaining though.

Problems:

• No mirage support yet
• The GUI doesn't show any numeric values, only an estimation bar
• It's not balanced yet: all buildings and all infantry has the same settings now
• No animations yet
• Some TODOs

Questions

• Currently, re-winning capture points can be both by garrisoning and attacking your own building. Maybe one of the two is enough
• Territory decay converts towards gaia for unconnected terrain, and to an enemy player for enemy terrain. This may look strange for automatic converting gaia buildings

[sanderd17]

The new attached diff should work with mirages, and the GUI looks good enough now.

The capture point reduction has changed from proportional, to distributed flat rates. In the former case, an owner with almost no capture points remaining could still own the building if two other enemies were fighting for it. In the case, the owner is defeated quicker if he doesn't attack back.

Next to that, the option to allow training units, researching techs and constructing buildings from foreign entities (entities that don't belong to the proper civ), is settable in the Builder and ProductionQueue template. By default, it is false, which means you now can't train any units from different civs.

Territory decay has been changed back so that it can only automatically decay towards Gaia, and that Gaia-owned buildings don't decay.

The main remaining stuff now are the balacing and giving animations (perhaps the healing animation as a placeholder).

[sanderd17]

Version 3 is ready for review IMO. It should also be playable with the current stats.

Balance on the attackers side:

• All fighting units take 3 capture points per second when attacking a building (except elephants)
• Melee Elephants and mechanical siege engines use their crush attack to damage buildings like before

Capturing also becomes more effective when the health of the target is reduced. If a building has only half the health, units take double as much capture points. So when combining siege engines and capturing units, the building usually gets captured right before the siege engines completely demolish it. However, capturing such a heavily damaged building makes it very vulnerable for any future attacks on it.

Balance on the defenders side:

• Mechanical siege engines can be captured easily, they have only 100 capture points (so it takes about 3 seconds to capture with 10 units, which means you always must protect your siege engines).
• Houses and dropsites are also relatively easy to capture with 300 capture points. However, capturing only those buildings without capturing the base has no use, as it's just as easy for the defender to capture it back.
• Most buildings are medium hard to capture with 1000 capture points.
• The CC is hard to capture with 3000 capture points, which normally requires you to use a combination of damaging with siege engines and capturing with units to take over a base.
• The fortress is even harder to capture with 4000 capture points
• Walls cannot be captured, only destroyed

Garrisoning also gives 3 capture points per unit per second to the owner. So there must at least be more attackers than people garrisoned in the building the capture it at full health. If a building also shoots more arrows based on the garrison count, then it becomes very hard to capture a garrisoned building.

[sanderd17]

Version 4 fixes an issue with fields (capture and resource bars overlap), an issue with packable entities (the capture points were reset on (un)packing), and also fixes the training tooltip to display the capture attack.

[mimo]

In 16549:

petra: let the AI know it can build a new base around a captured cc,refs #996

[sanderd17]

In 16550:

Implement building capturing. Fixes #996