coll, phmo, and ???

Snaku · Post by **Snaku** » Wed May 03, 2006 7:25 pm

Ok, so I messed with a pelican for the first time today. Never bothered before 'cuz it's huge, but with bsp conversions we can have huge maps now. So... this thing has altered my whole understanding of collision. Like coll is projectile impact. Phmo is physical impact. And apparently there's something else for impact with the terrain? I'd always thought that was phmo based, but now it seems it's not. Any idea what it is?
A few things I've noticed is that MC has two "contact points" one in each foot, and since he never turns upside down (at least while he's alive and not in a vehicle) his feel will always touch the ground. The warthog has markers for the tires, which, if nulled, will leave the wheels sinking into the ground and the hog will be all flippy. Not as much as the pelican, but a little--but it still rests on the ground.
So what is this third kind of collision? Is it just in the phmo still, but the pelican lacks that particular part? It obviously has phmo since you can walk on it, and it will collide with machs exactly as it should, so what's the deal?

sundriedprawn · Post by **sundriedprawn** » Thu May 04, 2006 12:53 am

well as the pelican never touches the ground i doubt it will have one

xzodia · Post by **xzodia** » Thu May 04, 2006 5:25 am

we spoke of this a while ago snaku dont you remember? about giving the pelican hog wheel markers?

n64nerd · Post by **n64nerd** » Thu May 04, 2006 5:33 am

funny, I think I've hit the groung before in a pelican... are you talking about the way it rolls around on the ground? I think they just gave it a roundish phmo. it never truly touches the ground in campaign, so why go through all that trouble? also, I'm not so sure about coll being so straightforward. if you null out the marker for the cab of the banshee, you can shoot through where it was, but still step on it.

xzodia · Post by **xzodia** » Thu May 04, 2006 5:47 am

just to clear up PHOMO: physical collision (ground and objects) COLL: proj collision

Snaku · Post by **Snaku** » Thu May 04, 2006 7:05 am

Yeah, coll is only for bullets. You can break off a bone of a vehicle (like the cab) and you can shoot through the place it used to be, but still stand on it.
The wierd thing is that the pelican rests solidly on a mach. Must be the phmo. It'll collide with the mach just as it should, and you can walk to the very edges of the wings without falling through. It seems the phmo is just fine (as far as coming into contact with bipeds or machs, and probably other vehicles and scen and stuff). I'm going to throw out a theory here that there are contact points at the edges of things (in mc it'd be his feet, in any vehicle it'd probably be any major corner) that can't pass through the bsp. Oddly, though, I found mc's contact points, but, if my theory is correct, they must be named differently for everything else.
Also, it seems as if coll might be wrapped around the model similarly to the shaders. I tried giving my motorcycle the coll of a ghost, but it seemed to still be just as big as the hog is normally. It just made it much easier to destroy and it seemed the gas tank was on the side in about the area it would've been for the ghost... but it didn't actually destroy the hog. It did, however destroy the attached ghost. Swapping out the phmo, however, resulted in being able to walk through the hog right up to where the ghost would've been--it even had the ghost's wings. It also was not very drivable as the phmo seemed to be dragging on the ground.. but it still animated correctly.
Anyway, I have a theory that, if correct, could fix the flippyness of the pelican, and maybe improve it in other ways, too.

n64nerd · Post by **n64nerd** » Thu May 04, 2006 8:33 am

I'm sorry, I might not have been clear. I know what coll and phmo are, but I was saying it's not just another object that dictates the collision; it's probably a collection on models that are referenced in many tags, etc. I guess we've established that coll is referenced in the bone tag and not the markers.
I think we need to dive into the coll and phmo plugins and see what we can find.

SyrinEldarin · Post by **SyrinEldarin** » Thu May 04, 2006 8:39 am

Erm, I'm pretty sure he meant that, when you REST a pelican on top of a mach, its collision is just fine, but it goes apeshit on BSP.

Snaku · Post by **Snaku** » Thu May 04, 2006 10:04 am

Well, I've decided that it is indeed phmo that dictates how an object interacts with the bsp, but it's apparently a different part of the phmo. (I decided this when I gave a vehicle a diff phmo and it collided with the bsp just like the new phmo should've. My explorations into phmo are going kinda' slow, though. I think I've spotted a few numbers that appear to be coordinates, though, so I'll tinker a bit. It'd be awesome to be able to edit phmo even if it's a bit sloppy. We could fix holes in machs, and scen. Resize vehicles. Remove the legs from the scarab...

xzodia · Post by **xzodia** » Thu May 04, 2006 10:17 am

snaku wrote:Remove the legs from the scarab...

you'd love that snaku wouldnt you? i had been intending to look at phomo and im short of somthing to do at the mo so nows as good a time as any

Snaku · Post by **Snaku** » Thu May 04, 2006 12:24 pm

Yeah, I would. I could go back to my very first plan. The one that's been on hold for-freakin-ever.

Punk Rock0905 · Post by **Punk Rock0905** » Thu May 04, 2006 1:23 pm

This is just a thought, but maybe they just didnt finish the phmo model for the phantom/pelican. I fail to see how you can rule that one out. It wouldnt be the first time bungie was lazy about coll/phmo.

xzodia · Post by **xzodia** » Thu May 04, 2006 2:02 pm

that doesnt mean it cant be fixed tho

Snaku · Post by **Snaku** » Thu May 04, 2006 7:23 pm

Yeah, they didn't finish it. It seems likely they intended it to be usable as a vehicle, but then before finishing they stopped. It does have a whole control scheme/driving physics of it's own, which it wouldn't need for scripted cutscenes.
They would've finished it's phmo in regards to bipeds because of the parts of the game where you can run into it, but they wouldn't have needed to fix it's terrain phmo. I guess I was just surprised to realize these two things were different.
And yes, that doesn't mean it can't be fixed, or at least some sort of workaround found to keep it from flipping.

n64nerd · Post by **n64nerd** » Fri May 05, 2006 5:41 am

I don't believe they were going to put the pelican in, or else they were just toying with it. the ai does control the pelicans in some situations; on delta halo, if you stand under the warthog pelican, it will move over before detaching the warthog. there never needed to be terrain collision, so why put it in?

I, personally, would like to see a working warthog with its chassis a story high.