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2018-06-28T21:17:26Z

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wiki>Sebbas: Created page with "= Week 3 = My main task this week was to examine the pointcache which currently only stores and refills smoke grid data. I figured that since smoke and liquids are so similar (l..."

2016-06-11T17:21:14Z

Created page with "= Week 3 = My main task this week was to examine the pointcache which currently only stores and refills smoke grid data. I figured that since smoke and liquids are so similar (l..."

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= Week 3 =

My main task this week was to examine the pointcache which currently only stores and refills smoke grid data. I figured that since smoke and liquids are so similar (last week I decided to merge them into one single modifier for that same reason) their cache files should be treated equally.

=== What's been done ===

* Although they're similar, I needed some way to distinguish smoke and liquid setups. This is important for later setting domain parameters but also because of the different file formats: liquid simulations store surface data in <tt>.bobj.gz</tt> files, smoke volume data is stored in the Blender specific <tt>.bphys</tt> pointcache file format. So I added some flags to account for liquid setups and made my Mantaflow script setup more modular (e.g. a plain Mantaflow solver object can handle smoke and/or liquids). ({{GitCommit|rBd3c57bc244c0}}, {{GitCommit|rB05c03b652628}}, {{GitCommit|rB836db6c99046}})

* The next step towards liquid caching was to write the liquid surface files to the correct location on disk. Here, I was able to reuse the smoke cache structures. That is, I reused the smoke cache GUI and all the logic behind path parsing and custom file names. All in all, liquid cache writing works now. ({{GitCommit|rB7abab97769c5}}, {{GitCommit|rB5a8340634080}})

* Finally, after writing one needs to be able to read the cache. And this is where I am currently at. So far, I found that I might be able to reuse the Elbeem <tt>.bobj.gz</tt> read function. (https://developer.blender.org/diffusion/B/browse/master/source/blender/modifiers/intern/MOD_fluidsim_util.c$163)

* Last week I re-enabled the smoke simulation functions. This week I noticed that the high resolution smoke did not work anymore. The problem was a missing liquid inflow grid for high resolution (classic <tt>NULL</tt> pointer ...). So I added that grid and also think it should come in handy when implementing a high-res liquid option. ({{GitCommit|rBa3c04bdd56c4}})

* I took a closer look at <tt>sampleLevelsetWithParticles()</tt> from the Mantaflow source code to understand how particles are sampled. While the randomness and discretization factors play a role (see [[User:Sebbas/GSoC_2016/Reports/Week_2|last weeks report]]), the values from the phi grid do as well. So instead of filling the phi grid with -0.5 for every point inside the mesh, one can use the distance to the mesh surface. ({{GitCommit|rBe8863f0be170}}) I tried that approach, but found it produced less accurate meshes (see images). Thus, for now I will keep using my old approach. ({{GitCommit|rB0992e7f6861a}}, {{GitCommit|rB6c177d3d3098}})

{|align=center
| [[Image:Mantatorus_phi_fixed0.5.png|thumb|300px|Old approach - phi using -0.5 for points inside mesh]]
| [[File:Mantatorus_phi_variable.png|thumb|300px|New approach - phi using distance to mesh surface for points inside mesh]]
|}

=== Next up ===

* Get the liquid cache read mechanism working.

* Finish the video comparision I proposed last week. I need the cache reading to work first so that I can create comparable Mantaflow and Elbeem scenes. In my previous videos I always sideloaded the liquid surface files (don't need to test that again).

=== Questions ===

* Discuss <tt>sampleLevelsetWithParticles()</tt> with my mentor. Is interpolation the problem for less accurate meshes (especially on low-res grids)?

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Yamyam: 1版 をインポートしました

wiki>Sebbas: Created page with "= Week 3 = My main task this week was to examine the pointcache which currently only stores and refills smoke grid data. I figured that since smoke and liquids are so similar (l..."

Yamyam: 1版をインポートしました