Clipping?

[Mr-Fusion]

Does the HL2 engine still have clipping?

 

[Arno]

What exactly do you mean?
Every game engine needs clipping, or you could walk through every wall.

 

[Sulkdodds]

What do you mean, still have clipping? Do you mean does it still have clipping errors? Clipping is just the process that stops game objects going through walls and suchlike, but it's often done badly.

 

[CrazyHarij]

If not a single member on this forum will find a clipping error in the final game when it's released, I'll eat up my computer, piece by piece and film the process and post it on this forum.

 

[Mr-Fusion]

Yeah, clipping errors. In a mod like Day of Defeat if a player is really close to a door and you're on the other side you see their weapon sticking through. It also happens if a player is prone near a wall, sometimes you see their feet sticking through the wall.

It also happens when players die near walls, though i assume dying won't be a problem because of new physics stuff.

 

[RoyaleWithCheese]

If not a single member on this forum will find a clipping error in the final game when it's released, I'll eat up my computer, piece by piece and film the process and post it on this forum.

CANNIBAL!!!

 

[RandomPING]

That's how i get rid of all my old computers. I love your icon DeusEx2.

 

[qckbeam]

Clipping errors occur because the game engine performs collision calculations based on an internal representation of the in-game models, known as bounding boxes, or sometimes, hit-boxes. These boxes are most often a very crude representation of the actual in game model, and not detailed enough to cover things like fingers and feet correctly. As far as I know, HL2 still uses bounding boxes (albeit, more complex ones) like just about every single game out there (the only exception I can think of is Doom 3 which uses per-pixel collision detection), and will probably still have some minor errors with regards to clipping.

 

[Sulkdodds]

Well, we've already seen evidences of clipping errors in some of the screenshots...but then they were work-in-progress.

 

[qckbeam]

It would be stupid for Valve to waste resources on fixing small clipping errors like the ones we have seen, unless the rest of their engine was so well polished that they would be able to do it without a hit on performance.

 

[RandomPING]

Yea, a little clipping doesn't bother me. As long as i'm not falling out of levels, or a monster is half inside a wall, i'm fine with it.

I was falling out of walls in Prince of Persia... on my PS2! Now that's annoying, i expect clipping in a PC game, but not that kind in a console game. (good game otherwise)

 

[Neutrino]

Yeah, clipping errors. In a mod like Day of Defeat if a player is really close to a door and you're on the other side you see their weapon sticking through. It also happens if a player is prone near a wall, sometimes you see their feet sticking through the wall.

It also happens when players die near walls, though i assume dying won't be a problem because of new physics stuff.

I know what clipping errors are, but what's your point? Do you have a question about it or a comment? I don't know how to respond since I don't see any main point to your thread.

 

[ray_MAN]

Yes it does. In a screenshot a combine's foot went through another combine's foot.

 

[Shuzer]

Yes it does. In a screenshot a combine's foot went through another combine's foot.

That's nothing, watch the Traptown vid, the dumpster goes right through a combine and he's sticking through it lol

 

[FictiousWill]

Here we go with 3D graphics 101:

Clipping errors are not based on bounding-box calculations but are internal to directX. Polygons and their component pixels are clipped when drawn to the screenbased on what are called Z-Buffer calculations, which take advantage of a buffer of memory used to store depth of polygons. Depending on the accuracy of your Z-Buffer, be it 8-bit, 16-bit, or more commonly 32-bit, polygons will clip more accurately, at the cost of processing power. When you see a combine's foot going through another's body, this is not a clipping error. A clipping error would be the combine's foot inside another's body, but you are still able to see the foot. Another example would be seeing a sliding HL1 door through the wall it slid into. These kinds of errors (when one thing sticks through another) are instead called collision detection errors.

Collision detection errors are when ingame objects 'clip' through each other. The internal clipping of engine is working fine when you see a combine foot going into another combine. The computer knows quite well that that foot is inside the other combine, and it has drawn it accordingly. No clipping errors. The game engine is what handles these kind of errors - which do relate to bounding boxes. The engine should realize that the foot is in the wrong place, and move the body on the ground accordingly, or change to movement of the standing combine.

Clipping errors are not caused by the engine, they are a result of the buffer depth internal to DirectX. Collision detection errors are a result of an internal engine error, such as the foot going through the wall.

 

[MultiVaC]

There is really serious clipping in Bugbait, the Ant Lions hit the Combine right through those little bed things that they use for cover. Personally, I think this really needs to be fixed. I can live with the guy sticking through the dumpster, but the Ant Lions literally attack through those bed things.

 

[ray_MAN]

That's nothing, watch the Traptown vid, the dumpster goes right through a combine and he's sticking through it lol

Yeah I notced that too. But, that was obvious so I dodn't post that. I posted the thing about the screenshot because you really have to look hard to see it. (Well, not really)

 

[The Dark Elf]

Don't forget those errors were all fixed some time ago. There will probably be the odd errors here or there but I doubt players will be paying attention to those in too great a detail while their getting their arses kicked by the combine.

 

[FictiousWill]

There is really serious clipping in Bugbait, the Ant Lions hit the Combine right through those little bed things that they use for cover. Personally, I think this really needs to be fixed. I can live with the guy sticking through the dumpster, but the Ant Lions literally attack through those bed things.

Things clip, sure - but they're not clipping errors. The error stems from collision detection, the clipping is working just fine.

 

[Yatta]

Does the HL2 engine still have clipping?

Bounding boxes and collision cylinders for characters. You make them big enough so that no part of their body, in any animation pose can clip into a wall, and then they can't get around a level, or you can shoot 2 feet to the left of one and hit it.

Rag doll coomplicates things.

Not saying it all can't be done, but it's generally accepted that some amount of clipping is ok. Half a body going into a wall, maybe not. But, it's not a trivial problem to solve, or you wouldn't see it in any game. NO game can do clipping perfectly.

 

[Brian Damage]

Gabe was quoted in an interview responding to this very question. I think he said something like:

"Interpenetration is a bad thing..."

... which is typically vague, but seems to indicate that they've fixed (or want to fix) the collision detection problems.

 

[Yatta]

Gabe was quoted in an interview responding to this very question. I think he said something like:

"Interpenetration is a bad thing..."

That's crazy! I hate vague comments. :angry:

 

[clarky003]

I wonder if anyone knows why, 'interative objects' specifically seem to have bad clipping errors? more often with other interactive objects, mostley dead bodies. (the metal gurder and dumpster 'completely' errored on the clipping with the 'dead' combine soldiers, seemingly clipping error also has more chance of occuring with a dead corpse/corpses, 'an inactive character')... why why why?! and how hard could this possibly be to correct!? to the point of consistently... proper working.. clipping within the game.(no matter what objects)

 

[The Dark Elf]

I wonder if anyone knows why, 'interative objects' specifically seem to have bad clipping errors? more often with other interactive objects, mostley dead bodies. (the metal gurder and dumpster 'completely' errored on the clipping with the 'dead' combine soldiers, seemingly clipping error also has more chance of occuring with a dead corpse/corpses, 'an inactive character')... why why why?! and how hard could this possibly be to correct!? to the point of consistently... proper working.. clipping within the game.(no matter what objects)

It'll depend on what method is used. bounding box, vertex or polygon. Bounding box is the quickest to calculate and far less strain on the engine, but its the least accurate, though for the most part its hard to notice in an actual game. Vertex is when only the points in each polygon and the line from each one to the other is taken into consideration, a little more effort on the part of the engine to calculate but more realistic than bounding box, but not quite perfect. Polygon where the actual polygon itself is used to check nothing is crossing into it, the most cpu intensive of the three but also the most realistic. The more polygons involved the slower calculations are for the polygon method.

On a slow machine, the bounding box method is the best choice, no clipping but not very accurate, and only those parts with a bounding box will be "seen" in the calculations, so smaller area's with no bounding boxes will still clip. Vertex is often used in pre-rendered/calculated simulations, the higher the polycount the less risk of errors but the slower to calculate. Polygons, no clipping atall as each polygon is calculated against another, its just the slowest method