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makit3d
PostPosted: Sun Mar 04, 2007 3:41 pm    Post subject: Overhangs and such... Reply with quote



Joined: 10 Feb 2007
Posts: 123

Here is a really big topic on a lot of terrain oriented forums. Overhangs, holes and jutting out of vertical surfaces.

There have been discussions ranging from using layered heightfields, metaballs, displacement and splines along with a few other options. Is this something that could be, or is already considered as, a feature for Grome?
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ALicu
PostPosted: Sun Mar 04, 2007 4:32 pm    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

Yes, overhanging is a feature many wants from a terrain, so of course it is considered for next versions. The current state of terrains (heightfields without overhangs) will still be used (at least for while) since it offers such great advantages in many ways (storage space, LOD, texture mapping, collision detection and so on). One possibility we’ve saw for next versions is to allow overhangs but usually use heightfields where possible. The current terrain tools will be extended to work on arbitrary geometry but in general will be still be recommended to use normal heightmaps when possible. Again I cannot give you an exact data when this feature will be implemented.

About holes, I think that these are possible right now, in a way. As you know masked terrain layers can be made transparent. So if you mark all of the terrain layers as in use and apply a mask brush to make them transparent you get a hole as the entire terrain is transparent (of course you would need to have all the layers with masks, not a single simple color layer). Another solution would be to mark per vertex the terrain tiles which are considered missing (we’ve done this for other projects but I think that by masks you get a nicer result due to texture filtering). In the future expect the types of terrain layers supported by Grome to increase considerably so extended information can be contained per terrain surface at various resolutions. One of these types can be information per tiles (or per other unit) about the terrain collision (solid vs penetrable) so you can indicate where in-game units can pass thru terrain as there is a hole there. This, for example, is especially useful for cave entries.
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makit3d
PostPosted: Sun Mar 04, 2007 4:42 pm    Post subject: Reply with quote



Joined: 10 Feb 2007
Posts: 123

Quote:
so you can indicate where in-game units can pass thru terrain as there is a hole there. This, for example, is especially useful for cave entries.

I was thinking of tunnels for trains (at least in my case) but it's all the same. Even something like eroded rock bridges (such as the scene in the new movie King Kong where they land on the beach and the woman runs down the beach and passes under a rock bridge).
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ALicu
PostPosted: Sun Mar 04, 2007 4:53 pm    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

Oh, I see. Yes, for that a special editing system will be needed. From what we’ve studied a voxel system can be suited for that (not voxel in the old way, when they’ve used it for rendering, but used for modeling). This system will allow users to create arbitrary geometry by carving or adding terrain mass in any direction with automatic texture mapping without visible stretches. We are planning to add such a system sometime in the future, and would be used for carving the normal heightmapped terrain (to create tunnels) and also to create rocks like you’ve described.
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Mihai
PostPosted: Mon Mar 05, 2007 8:57 am    Post subject: Reply with quote



Joined: 26 Jan 2007
Posts: 85

Quote:
I was thinking of tunnels for trains (at least in my case) but it's all the same

Hi
You can add tunels, caves etc. right know in Grome, but those have to be external 3d objects and the entries can be paint on the terrain with transparency masks.

Best Regards
Mihai Daranga
Art Director
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Hunnenkoenig
PostPosted: Mon Mar 05, 2007 7:58 pm    Post subject: Reply with quote



Joined: 04 Mar 2007
Posts: 42
Location: Vienna/Budapest

Mihai wrote:

Hi
You can add tunels, caves etc. right know in Grome, but those have to be external 3d objects and the entries can be paint on the terrain with transparency masks.


Does this mean, I can go into the cave without any noticable change in the gameplay or do I have to use i.e. loading screens?
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ALicu
PostPosted: Mon Mar 05, 2007 9:25 pm    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

All that depends on your engine. Grome doesn’t impose any restriction on that, it is only creating the world. The engine should detect when you enter the cave and apply special loading and visibility algorithms.
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makit3d
PostPosted: Mon Mar 05, 2007 10:09 pm    Post subject: Reply with quote



Joined: 10 Feb 2007
Posts: 123

As I understand this the transparency mask tells the terrain 'I am to be ignored, but I still technically exist'? This method will tell the respective engine to not draw that portion of the terrain and the object(s) within that void are visible and solid? Also, by removing the mask the terrain is recognized and made visible and interactive again?

So, in essence, I wouldn't be removing the terrain with a transparency mask. I would simply be telling my respective engine to believe that area of the terrain is gone and to recognize the junk I put there instead.

Is this correct?
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Hunnenkoenig
PostPosted: Tue Mar 06, 2007 12:05 am    Post subject: Reply with quote



Joined: 04 Mar 2007
Posts: 42
Location: Vienna/Budapest

Oh, ok. Now I get the picture. Thanks!
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ALicu
PostPosted: Tue Mar 06, 2007 8:46 am    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

Quote:
As I understand this the transparency mask tells the terrain 'I am to be ignored, but I still technically exist'? This method will tell the respective engine to not draw that portion of the terrain and the object(s) within that void are visible and solid? Also, by removing the mask the terrain is recognized and made visible and interactive again?

So, in essence, I wouldn't be removing the terrain with a transparency mask. I would simply be telling my respective engine to believe that area of the terrain is gone and to recognize the junk I put there instead.

Is this correct?


Yes, you are correct.

If you keep the "hole" information in a specific layer (or other data organization) inside your engine, you can, for example, make an exporter that go thru all the layer masks and if in one place founds out that all are transparent there you mark a hole in your data.

Or, simpler than that, you can have a color layer created inside Grome you call, for example, "Holes", and you paint on it with a certain color where you want your holes to be. You will not see the holes in Grome as a hole (but by specific colors) but at export time you use this layer to save the "holing" information.

What I want to emphasize here is that you can use the terrain layers for more than just visual representation of terrain colors. You can use them for AI for example. Just have a layer that you decide to always call "AI" and use white where units can go and black where they can't. If you decide to have units not crossing a road, not going above an altitude and not climbing above a certain slope you can procedurally or manually generate this layer as any other texture layer using colorgen and color brushes.

Of course, the texture layers can contain only color information and you must encode your AI information in that range. But in the future Grome versions we will add more types of layers some of them carrying user defined data.
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zoombapup
PostPosted: Wed Jun 27, 2007 11:55 am    Post subject: Reply with quote



Joined: 27 Jun 2007
Posts: 10

If you take a look at the Crysis engine, they got around the problem of holes and caves by adding support for voxel based volumes "on top" of the landscape.

So basically, you make a big hole in the landscape heightfield.

You fill it in with a big voxel volume.

You then allow editing that volume.

We did something similar in Worms 3D, by using a skinned voxel volume we could have arbitrary completely destructable levels. Works great but I think the advantages of heightfields in terms of coding tools and renderers greatly outweights the advantages of other types of editing. So I think thier approach is actually the most sane (i.e. dont change the heightfield method to be more general, instead supplement the functionality with a further editing method).
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ALicu
PostPosted: Wed Jun 27, 2007 12:08 pm    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

Yes, you are absolutely right. Heightfields are too good performance wise, at least for a while I don't see them being abandoned. Voxels are good for couple of reasons (you can have sculpting tools for fast creation and also have destructible environments). But making them the rule around the map is a waste.

You can also get away with heighfields + generic meshes (edited in other modelers). I suspect Crysis voxels are just there as an eye candy feature (to impress when you need to license the engine). They could have easily used generic meshes to do the job.

We also study voxel editing as a fast way to create rocks, caves etc (and sometime in the future we will have it implemented in Grome). But I suspect that the common user will get a normal mesh in the end (with his exporter) because many will not support voxels natively in their engines.
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zoombapup
PostPosted: Wed Jun 27, 2007 12:11 pm    Post subject: Reply with quote



Joined: 27 Jun 2007
Posts: 10

Absolutely. But to my thinking its actually the best overall mix of ease of programming and ease of use.

Heightfields are fantastic for most terrain needs.

Voxels are great for making holes in volumes.

So the combination really works.

If you look at the crysis engine editor app demos btw, there are a few things you could use in grome. They have a road placement system that looks really good. The voxel editor is really user friendly (basically move abig red ball through space to "cut" holes).

What I'd expect is that you'd rarely use a voxel volume. Perhaps only for a specific case. So it'd be rare rather than used everywhere.

Plus, they had shadowing issues within the voxel volume if you look closesly Smile
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ALicu
PostPosted: Wed Jun 27, 2007 12:15 pm    Post subject: Reply with quote



Joined: 12 Feb 2007
Posts: 1326

About voxels (probably you know this): http://www.home.zonnet.nl/petervenis/

And also a road system is already in works for version 2 Smile
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zoombapup
PostPosted: Wed Jun 27, 2007 12:28 pm    Post subject: Reply with quote



Joined: 27 Jun 2007
Posts: 10

Hehhee.. cool, thats not far off what we were doing (although we did have a few more restrictions I would imagine).

I do like the fact that you can make wholly destructable environments, even if like in our case, they tend to look a bit chunky.

Here's a shot of how ours looked.

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