Ai refactoring

[stohrendorf]

@serishema I did my best to understand why the AI goes crazy sometimes, and it seems the step and drop limits and their checks are negated. I tried to fix these things and make the original AI code a bit more readable. I'm not feeling really confident about these changes, they might make things even worse. It would be nice if you could take a look at this and mark any WTFs or ask for clarification when there's anything that's confusing. I will add comments or further refactor the code to hopefully clean things up.

[serishema]

I played the first 3 levels. These are the things I noticed about enemy behaviour with this branch.

• bats still "bounce" off the ground after dying from being shot. This is consistent and occurs every time.
• I was able to get a wolf stuck on a slant block that is lara's waist height. in this screenshot you can't see the wolf past lara's head, but it's there.
• in caves before the door at the end the wolves get stuck on the side of the stairs and don't attack up the stairs like they normally do. This is one box high (ie lara can just hang from the edge without touching the ground). I couldn't find a specific drop/step limit in wolf.h/wolf.cpp so I assume it's a quater sector inherrited from AIAgent. again the wolf is behind lara
• In City of Valabamca the bear at the end can get up the stairs to the 2nd level which i'm pretty sure it's not supposed be able to.
• In Lost Valley, raptors can get onto the temple platform and into the temple. Possibily because each step is not larger than the step limit?

[stohrendorf]

• Bats bouncing off the floor when falling is OG behavior. The AI is handling dead bats just like living entities, which means the gravity is working against the bats penetrating the floor, which causes a correction. See the lines near the comments fly movements ended up penetrating the floor and fly up from the floor. (Edit: To fix this, the AI must be disabled when bats die, and the gravity simulation with fly speed limitation must be done manually.)
• Wolves have a drop limit of -1024 and their default step limit of 256, see gameflows/tr1/object_infos.py, so this is a bug as the AI should have calculated a box path from the lower end of the steps. Which also means the wolf on the slanted sector should be able to just jump down from it. This means that somewhere the drop/step limit checks aren't applied properly.
• Raptors being able to enter the temple is fine, your explanation is correct. I've also seen the bear in City of Vilcabamba get up there for quite some time now, so if that's a bug, it's caused by something outside of the changes of this PR. Both have their default stp/drop limits of +/-256.

[stohrendorf]

One more terrifying thought... I seriously hope the box floor/ceiling heights aren't negated, too. But if I remember correctly, when I once exported the level geometry to OBJ, the boxes looked fine and matched the level geometry, but I'm not sure whether I negated the heights without questioning it enough.

[serishema]

Unfortunately I can't tell from the code. My guess would be that if the floor/ceiling heights were negated then these changes would have made all enemies behave very strangely which isn't happening.

I'm happy with everything, except for the wolves getting stuck. Do you want to address that in a seperate PR, possibly in the future or deal with it here?

if it's to be addressed in the future i'm happy to approve these changes.

[stohrendorf]

I found the issue with the pathfinder, it's just another case of "reverse thinking".