An easy explanation to Dual Contouring?

Joe · 2017-11-13T21:27:43

1 hour ago, frob said: This is a general reminder to keep the conversation civil. Some private warnings have been issued. No more personal attacks. Let's keep it focused on the topic of the mesh data processing. Quote Note for member Several of your replies in the Dual Contouring discussion have been abusive, and a few border on useless. In one reply you state that you don't remember a technique but it is better. In another your declare that the person asking the question doesn't understand your answer in an insulting way, yet make no attempt to help them understand. Some of the replies include subtle personal attacks, which are not tolerated on this site. Statements like "stop being rude" and "work on your social competence!" are not okay. Please tone it down. Replies should generally help people learn and become better game developers, not insult them. Well - fair enough. I apologize for being rude myself, instead i should have explained why Questers quoted commend was wrong: If you look yourself to the video, it's clearly visible that the geometry is just a deformation of grid aligned cubes. Deformed cubes can of course have sharp features. Dual Contouring would contain intersections with the grid and also new geometry inside the cubes for the sphere shown in the video. (I did not say Surface Nets are 'better', just 'easier to implement' - so probably attractive for a beginner.) Quote I have already said: they clearly say on their website they are using Dual Contouring. But that's really not what I want to discuss here. I won't commend on why they state on their website their technique is BASED on dual contouring (whatever that means exactly), but you see that there was no interest in any further explantation as you suggest. And that made me angry because of the time it took me to find information about the technique i remembered. I still perceive this reaction as ignorant. Asking for help and then rejecting valid points it is not nice either and contradicts public discussion. But i took that much too personal. Shouldn't get upset that fast, even on a bad day. Sorry again, guys! Edit: ... and sorry for wasting even more space

Math and Physics Programming Algorithm C++ Behavior

Started by QuesterDesura November 09, 2017 05:13 PM

24 comments, last by JoeJ 6 years, 5 months ago

swiftcoder

18,997

November 11, 2017 01:39 AM

9 hours ago, QuesterDesura said:

If for example in my game a Cube gets placed by the player then I will create volume data containing the coordinates of the 8 edges, right?

Well, no. You volume data is usually a regular grid (can be 1-bit empty/full data, or floating point density values). You'd initialise the entire block of volume data to empty (i.e. zero). Then if the player places a cube, you'd intersect their cube with the volume data, and set each cell that intersects the box to full (i.e. one).

If you are looking for Minecraft-style terrain, where everything is cubes, then Dual Contouring is going to overcomplicate things significantly, and there are much simpler methods.

Tristam MacDonald. Ex-BigTech Software Engineer. Future farmer. [https://trist.am]

QuesterDesura

Author

November 11, 2017 08:45 AM

I'm looking for something

" rel="external">like this. They are using Dual Contouring. I think I now have gotten an Idea how Dual Contouring could be working and I will try to make a simple implementation and see if it works.

QuesterDesura

Author

November 11, 2017 05:38 PM

I have gotten some stuff working now. I used the Unity Editor to make it easier to see what I'm doing. I have "translated" the Code from the Github project in C# and changed/removed stuff that I don't understand. This is my first test:

The small cubes presents voxels which are inside the mesh. Next steps will be to also let the algorithm run through the other sides and make a solid shape.

This is how it looks with a distance of -0.5 to all edges:

I think/I hope I have now understood how this algorithm works. I will post again if I encounter new problems or hopefully I can get some more results and share them.

JoeJ

4,198

November 11, 2017 10:48 PM

13 hours ago, QuesterDesura said:

I'm looking for something
" rel="external">like this

The video looks like they do not use dual contouring, they only snap voxel vertices to the nearest point of target geometry, which should be a lot easier to implement. (Limitation is probably: You can not have two surfaces in one voxel.)

Unfortunately i do not remember a proper name or explantation of the technique, but there are a few around. Maybe someone else...

QuesterDesura

Author

November 11, 2017 11:20 PM

31 minutes ago, JoeJ said:

The video looks like they do not use dual contouring, they only snap voxel vertices to the nearest point of target geometry, which should be a lot easier to implement. (Limitation is probably: You can not have two surfaces in one voxel.)

Unfortunately i do not remember a proper name or explantation of the technique, but there are a few around. Maybe someone else...

They are using Dual Contouring which you can also see when you watch the full video, its also stated on their website.

sjhalayka

November 12, 2017 12:55 AM

@QuesterDesura -- can you please share your code on GitHub?

JoeJ

4,198

November 12, 2017 07:13 AM

7 hours ago, QuesterDesura said:

They are using Dual Contouring which you can also see when you watch the full video, its also stated on their website.

Still disagree. See here (1:10):

The wireframe morphs directly from deformed geometry to voxels. No geometry is generated inside a voxel like dual contouring or marching cubes would do.

Also the edge artefacts at the beginning when they build a structure from 3 boxes may hint this (missing vertex to represent multiple surfaces inside one voxel.)

Of course i do not know if that's all functionality they have.

JoeJ

4,198

November 12, 2017 08:30 AM

Found what i have in mind, it's called 'Surface Nets'

https://0fps.net/2012/07/12/smooth-voxel-terrain-part-2/

http://www.merl.com/publications/docs/TR99-24.pdf

Also found this about dual contouring, if you don't know yet, seems quite complete with code: http://ngildea.blogspot.co.at/

QuesterDesura

Author

November 12, 2017 10:38 AM

2 hours ago, JoeJ said:

Found what i have in mind, it's called 'Surface Nets'

https://0fps.net/2012/07/12/smooth-voxel-terrain-part-2/

http://www.merl.com/publications/docs/TR99-24.pdf

Also found this about dual contouring, if you don't know yet, seems quite complete with code: http://ngildea.blogspot.co.at/

At 1:10 you can see that the cube is not being smoothed, if that would be Surface Nets then the cube wouldn't remain sharp also as I have already said: they clearly say on their website they are using Dual Contouring. But that's really not what I want to discuss here.

JoeJ

4,198

November 12, 2017 11:21 AM

39 minutes ago, QuesterDesura said:

if that would be Surface Nets then the cube wouldn't remain sharp

You have not understood Surface Nets.

An easy explanation to Dual Contouring?

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