M12P6 - Chill Out Iceman - You can enter the turret ontop of the factory from the ground

[Mortecha]

Thank you for the swift bug fix for the previous bug, that was amazing. I have another that I noticed while I was playing through the game in my last play through.

Describe the bug The turret on top of the factory can be entered directly by standing next to it on the ground and entering it like any other turret.

Normally the player is supposed to summon the helicopter from the 3 dreaded pads placed over the map, then once they have the helicopter, fly it on top of the factory to then use the turret to destroy the surrounding bunkers and the factory door.

To Reproduce Steps to reproduce the behavior:

1. Begin the mission
2. Successfully get to the side of the turret
3. Enter the turret

Expected behavior The player shouldn't be able to enter the turret from the ground but instead fly to the roof of the factory first.

Screenshots

Desktop (please complete the following information):

• OS: Windows 11
• Version: 189FA1C

[segrax]

Haven't tried the Amiga version, but this behavior is the same as the dos version, am able to get into the turret from the ground

[segrax]

Can verify behavior is the same on Amiga

[Mortecha]

This makes me wonder if you could always do this. I'll have a go back and have a look.

[segrax]

far as i can tell yeah (i used the retail dos cd version and the amiga floppy version, on emulators).

no idea if was intended or not, presumably not, as it kinda makes the helicopter pointless?

[Mortecha]

An interesting quirk,

I'd say like most bugs in game dev, it was missed or they didn't have the time to fix before they shipped.

it does make the helicopter a pointless distraction, but since its a "feature" of the original, should it even be fixed?

[segrax]

depends who you talk to 😄

i have fixed a few engine bugs, but nothing map specific (although there is a fix in place for loading some map sprites in CF2, this fix comes from one of the original engines -- suspect it was the second? release on PC of CF2)

there is a list of fixes, although by the time I started documenting them, some had been forgotten. nothing really game play specific , mostly aesthetics and memory corruption issues which didnt break on Amiga / Dos

https://github.com/OpenFodder/openfodder/blob/master/BUGS.md

[segrax]

im not sure what the correct fix here would even be, guess the building would need to be extended by one tile to the right which should provide enough space to prevent troops entering the turret

[segrax]

or a map specific hack put in place to prevent entering from one side

[Mortecha]

The turret base has its own tiles, separate from the one normally used for ground turrets. I initially thought it was going to be some weird interaction with tiles placed on top of each other to create the building but turns out its not the case. The tile in question if a map specific hack was the way to go is 359.

im not sure what the correct fix here would even be, guess the building would need to be extended by one tile to the right which should provide enough space to prevent troops entering the turret

Same here, not sure what the best fix is for this either. I suspect the collision works as intended, but its only when the player is entering does it seem to forget about the wall.

[segrax]

maybe it could be fixed by modifying the HIT/BHIT tables,

although im not sure if they are capable for this situation, or if it will just end up blocking access on both sides

[Mortecha]

I'm not familiar with how all this works at the moment, I'd love to spend some time to figure it out.

I suspect the collision works as intended as you can't walk directly on top of the factory from the ground, but its only when the player is entering an object does it seem to forget about the wall in between.

I wonder if the same logic applies to anything else parked close to a wall or cliff. Perhaps not, this seems like a unique edge case.

[Mortecha]

Nope, not unique.

I was able to replicate the bug in M24P4 System Off with the helicopter.

[segrax]

seems the data is right,

I've just extracted all the tile BHIT data, and the right column (X = 7) is set to eTerrainFeature_Block.. rest of tile 359 for ice is eTerrainFeature_Rocky2 (this is another grenade2 situation 😄 - in at least one place, Rocky and Rocky2 are treated the same)

And yep, there is no check of tile/height on attempting to enter a vehicle, its only distance based

[segrax]

You can walk right through the blocked? (this tile is probably replaced, so its replacement?) tiles once the turret is destroyed

[Mortecha]

Yep it becomes 339, I didn't even think to test if you could walk through it after it was destroyed! Good find.

[Mortecha]

It seems that the roof turret base and destroyed roof base are also flipped versions of the normal ground based turret, could this also impact the distance to enter it?

[segrax]

the right edge of 339 is still blocked, but i couldnt always walk in. i think the sprites can move more than 1 pixel at a time though, so its likely only when it aligns right on the edge that the block while walking is working.

regardless though, the entering vehicle check doesn't take into account the tile types at all, its a hard-coded distance of < 0x0D

[Mortecha]

Might be the best way to handle it, acknowledge its existence as a bug in the original game and let it be. I can foresee a fix for it becoming quite complicated and messy, and my understanding about the games inner workings are still only superficial.

I have another issue I've come across if you're keen to have a look, it wont be an original game bug and I suspect it will be able to be fixed.