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# Anfaenger

Member Since 19 May 2011
Offline Last Active Sep 18 2016 09:53 AM

### In Topic: Implementing position-based rigid body dynamics

03 September 2016 - 03:54 AM

Turns out PBD is not very suitable for simulating absolutely rigid bodies (?).

I quickly had spheres jumping around on a plane, but couldn't get rid of jitter (becomes visible if increase gravity or decrease the timestep).

Maybe, that's why they solve contacts on velocity level (like in most impulse-based engines).

As for constraints equations, these lectures are extremely easy-to-understand:

[2014, 'so this is my *ss', lol, sorry]:

https://youtu.be/b2An7OJJ-j0?t=45m51s

[2015]:

### In Topic: Space filling curves for 'concentric' flood filling?

16 June 2016 - 01:40 PM

If I understood correctly, Gray codes allow to visit vertices of the cube once,

but I need to walk over the whole surface of the cube.

I'm looking for a (bijective) mapping from integer points on the cube surface to single integers and vice versa (not necessarily a space-filling curve).

btw, it seems in 3D there are no space-filling spiral curves:

### In Topic: Work queue with condition variable - design issue

15 June 2016 - 01:19 PM

I'll go with the 'dummy-task-just-to-exit-the-loop' approach.

My actual problem was creating/generating/loading/meshing voxel chunks as the player moves through the world (or growing the loaded area when a new world is created).

### In Topic: Closing cracks between neighboring chunks with different LoDs in a non-cubica...

22 March 2016 - 05:11 AM

yeah, I've run into the same problem as he did:

http://ngildea.blogspot.ru/2015/07/fixing-seams-bug.html

basically, the seam nodes gathered from the chunk's neighbors

generate polygons which coincide with the neighbor's polygons.

i.e. octree nodes collected from a neighboring chunk generate polys between themselves.

when later the neighbor's mesh is built, it will also generate the polys in the same positions.

maybe, there's a better algorithm for generating seams?

because all 7 neighbors (connected to the chunk via a seam) must be re-meshed whenever the chunk's LoD changes.

### In Topic: Closing cracks between neighboring chunks with different LoDs in a non-cubica...

21 March 2016 - 09:11 AM

Sorry, I didn't understand why the problem should be inversed, drawing the complicated buildings first and then filling the terrain.

Did you mean I should connect terrain to buildings?

btw, I almost solved the seams problem yesterday using octrees.

All cracks are filled correctly, but the seam generator produces overlapping polygons (which causes Z-fighting).

Here's an ugly picture showing a grid consisting of 16x16x2 chunks (resolution of each chunk = 16^3) with some Simplex noise clipped by a box and a few shapes added on top:

I haven't implemented LoD selection yet, only experimented with changing LoDs on a single chunk.

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