Dual technologies research bug

[Enrique]

You can research both "Dual" technologies if you click quickly enough. The player must be able to research only one. Tested in different civs in barracks, defense towers, temples, fortress and mills.

[zoot]

Confirmed with 'Iron Ax Heads' and 'Wheelbarrow' on Gaulic Mill.

[historic_bruno]

The UI lag strikes again :P I guess the check in the tech manager isn't correct yet?

[zoot]

As historic_bruno indicates, there's really two issues at play here:

The most obvious and egregious one is that the relevant simulation component (tech manager) does not properly check whether the paired tech has already been researched. This is the actual exploit and can probably be easily fixed by someone who knows the code.

The other, more subtle and IMO more interesting issue is the UI lag. The fact that it is even possible to click both buttons points to a more general flaw in the way the UI works.

Strictly speaking, what it does is correct: when you click one of the tech buttons in the pair, it issues the order to the tech manager and then waits patiently until the research order is queued. Once the research order shows up in the queue, it removes the button for both the queued tech and its pair from the UI.

Problem is that it takes a whole turn from issuing the order until it shows up in the queue, and turns take long enough time to be humanly perceivable. This creates a sluggishness in the UI which IMO is highly undesirable, because it leaves an impression that the game performs poorer than it actually does.

Since we can't count on the simulation being as fast as the UI (especially in the case of networked multiplayer), it would IMO be nice if the UI did some kind of interpolation. A simulation of the simulation, so to speak. It might be somewhat of an undertaking to implement, but I believe all modern RTSs do exactly this - particularly after the emergence of internet gaming, where network lag can really drag the user experience down the drain otherwise.

It's not something I would be able to do in a few hours, though, so I'm probably veering a bit out of the scope of this ticket here. Just wanted to suggest it in context :)

[leper]

In 13395:

Check if one of the technologies in a pair is already in progress. Fixes #1820.