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Pagusas · Jan 20, 2013

In the last 15+ years graphics have come a long way, with tons of improvements and methods to take care of common issues. Anti aliasing to mediate jaggies, texture filtering to combat blurry textures, vsync to handle screen tearing, yet one universal issue you still find in all games has yet to ever see even so much as an acknowledgment for designers. That issue is object clipping.

Every game has instances of objects, characters and particles magically moving through other objects, character arms turning into ghost as they travel seamlessly through the wall right next to them. Why does this still happen? Does it just take to much processing time to have all objects have some sort of collision detection to prevent such things? Is it because so many things in modern games are baked or prescriptive animations that will run there corse no matter if there is an object in the way or not?

How does this get solved? I was playing assasins creed 3 today and in the middle of a cutscenes the charters whole arm goes through a character right next to him, completely breaking any emmersian during that scene. Granted the game has many bugs, but this is one you seein all games. Skyrim, assasins creed, gta, bio shock, uncharted, all have loads of clipping problems. Will it ever be solved or fixed?

Durante · Jan 20, 2013

Pagusas said:
Does it just take to much processing time to have all objects have some sort of collision detection to prevent such things?

Yes.

Pagusas said:
Will it ever be solved or fixed?

Sure, you just need more power. The good thing is, in many cases solving it (with more power) could actually mean less developer effort in the end. E.g. instead of manually animating the movement of cloth on a character, it's calculated automatically in realtime.

Bony Manifesto · Jan 20, 2013

Pagusas said:
Every game has instances of objects, characters and particles magically moving through other objects, character arms turning into ghost as they travel seamlessly through the wall right next to them. Why does this still happen? Does it just take to much processing time to have all objects have some sort of collision detection to prevent such things? Is it because so many things in modern games are baked or prescriptive animations that will run there corse no matter if there is an object in the way or not?

You've pretty much answered your own question there.

oversitting · Jan 20, 2013

Because we have certain actions that are allowed and to program them in in a massive game requires to simplify much of it. Interfaces are used and thus software can actually be produced in relative time. What ends up happening is you can't calculate all of the models 100% and end up with clipping.

Not only that but models in the early stages of the engines are different than when the game launches. Im surprise games look so polished as it is.

Pagusas · Jan 20, 2013

I know some of the causes, i just don't understand why it hasn't gotten more attention or ways of being fixed like other graphical problems have been, as its just as ugly if not more so then the other things.

Hedja · Jan 20, 2013

To make something not clip, it either needs its own physics calculations whenever it collides with something else or the animations and combination of models need to be made in such a way they won't collide.

The former will take way too many calculations to make it seem natural and the result is simply not worth it while the latter can't be accommodated for every situation (custom equipment and capes for example).

Noogy · Jan 20, 2013

For the same reason all games aren't rendered at 10k resolution and feature 48x AA. It's either too demanding, or requires way too much optimization.

I still appreciate the art of 'level designing to hide clipping'.

I do believe that clipping and noticable LoD will go away one day, given enough horsepower. That's a realistic goal since it would actually require less work from developers.

Edit: Doh, I tend to think of distance clipping, should have read the OP more closely. But my points still stand.

Swifty · Jan 20, 2013

Doing triangle/triangle continuous collision detection for everything is just a bad idea.

AlexBasch · Jan 20, 2013

Just noticed this in Sleeping Dogs. Wei was wearing a bracelet and a jacket, when he was moving in the cutscenes the bracelet was still there. I don't know why the game doesn't just suppress the bracelet if you're wearing something that covers it.

UpperCaseN · Jan 20, 2013

You leave my clipping alone! I get plenty of unintentional amusement when I'm in a kick animation and my leg goes through the wall or when my sword weilding hero is walking past people and the sword goes straight through them with no harm

Kazerei · Jan 20, 2013

DonMigs85 · Jan 20, 2013

what's emmersian

Eaten By A Grue · Jan 20, 2013

Stealth Hotline Miami thread

M3d10n · Jan 20, 2013

Because everything is fake and there aren't actual objects in there. It's just a bunch of triangles being drawn as colored pixels on the screen.

Collision detection is expensive and in most games characters use a box, cylinder or capsule as a collision volume. What would happen to an arm animation of a dynamic object is blocking the arm? The animation is just a dumb sequence of positions and rotations for each limb.

Stuff like Euphoria does limb collision detection, but it's expensive and can have impact on gameplay (since the animation now dictates the actions, not otherwise).

AlphaTwo00 · Jan 20, 2013

KieferCrimson said:
Just noticed this in Sleeping Dogs. Wei was wearing a bracelet and a jacket, when he was moving in the cutscenes the bracelet was still there. I don't know why the game doesn't just suppress the bracelet if you're wearing something that covers it.

In cases like that, where we're talking about a high amount of character customization, to prevent things that are "layered" to clip, you either:

a) all customization things aren't just models, but models with collision (and CLOSE collision detection too in cases of clothing), which are costly. (This is why hair physics is still such a rare thing, and highly praised when looking done correctly)

b) the "cheaper" alternative is probably to build another character model with that option so that it doesn't clip. But this kind of defeats the entire customization, as someone would need to create EVERY available combination so things don't clip.

sakipon · Jan 20, 2013

I dislike it when characters with long hair have the hair going through their backs and arms and whatever. Yeah, challenging to get rid of, but just today I was looking at it happening in Mortal Kombat on Vita.

Dibbz · Jan 20, 2013

Collisions are not free.

SmithnCo · Jan 20, 2013

sakipon said:
I dislike it when characters with long hair have the hair going through their backs and arms and whatever. Yeah, challenging to get rid of, but just today I was looking at it happening in Mortal Kombat on Vita.

Yeah, that bugs the hell out of me. I remember it bugging me with Link's hat in a lot of the 3D Zelda games too.

Pagusas · Jan 20, 2013

I recall at the beginning of this gen seeing "demos" of advanced rigging and adaptive animation that would work its way around objects to prevent clipping. I recall seeing a character walk up fully modeled stairs and the animation and body adapting to the changes so the feet hit correctly on each step. Also recall seeing a basketball demo showing character on character collision that looked perfect. I'm guessing those were either bs, ortechthatjust end up being too resource intensive to use in the real productions?

Aguirre · Jan 20, 2013

i dont mind clipping if its done like in dark souls: when you hit a wall with a weapon/shield it clearly clips, however you are treated to sparks, sounds, debris and even a reaction animation. its a nice touch and gets round this issue.

Raonak · Jan 20, 2013

you underestimate how much work is involved in collision detection. its also something most people don't notice/care about.

Noi · Jan 20, 2013

I don't mind clipping in general cause there's tons of situations where you can't help having clipping occur especially if it's with bonus content not made to fit certain situations (See: RE5 costumes during regular play.)

When it DOES bother me though, is when it's part the main character's costume as something that he ALWAYS has on him/her. Like in Assassin's Creed III, they couldn't be bothered to make Connor's bowstring not clip into his body 24/7 even though there's not a single moment where he doesn't have the bow equipped. Lazy as hell.

Wasp · Jan 20, 2013

On the 360 version of Assassin's Creed III Desmond's white top is constantly clipping through his backpack. It annoyed me no end. On further inspection I discovered Desmond has developed a hunchback style tumour on his back which is what's protruding through his backpack. He really should see a doctor about that.

Baconsaurus Rex · Jan 20, 2013

DonMigs85 said:
what's emmersian

Sounds like some kind of cheese

Shining Sunshine · Jan 20, 2013

Here's a game without player clipping!

There's still level clipping though, and it takes a ton of processing power to make the Impact Engine work.

mclem · Jan 21, 2013

DonMigs85 said:
what's emmersian

Formed a prog rock supergroup with Lake and Palmer.

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