Add support for PLY proxy objects

[Theverat]

Planned workflow:

• Select object that has a long export time and/or makes OpenGL viewport sluggish (e.g. trees)
• Press a "make proxy" button (or a menu entry in the export menu?)
• Object is exported to disk as PLY and converted to a low-resolution proxy object in Blender

Implementation:

• The proxy has to support multiple materials. Back in LuxBlend we split it into multiple objects with one material each and parented them to one object, but this is far from ideal (user can accidentally move a part, and it is clumsy to use). A better idea:
  • Only one proxy object in Blender
  • Has properties attached with information about the multiple PLY files attached to the proxy and which material belongs to which PLY
• We will probably need to add a function to pyluxcoreforblender that exports a Blender mesh to PLY because the PLY exporter in Blender is written in Python and super slow.

Details:

• The preview mesh should have equal density over its volume (not depending on the original mesh density). Otherwise you get the problem that e.g. the preview mesh of a tree with highpoly leaves and a lowpoly trunk has almost no density around the trunk. (forum post)

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[neo2068]

ToDo List:

• [x] Add UI for proxy export in object tab
• [x] Add export code for ply file
• [x] Add external mesh handling during render export
• [x] Use the same names of shapes for proxy and high res meshes
• [x] Add buttons for manually add PLY files to proxies list
• [x] Add reload function for high res object when use proxy is unchecked
• [ ] Assign names to manually added proxy PLY files
• [ ] Check mesh normal smoothing on export/reimport
• [ ] On deselecting use_proxy ask if the high res mesh should be reimported
• [ ] Check proxy object name on reimport to correctly replace proxy object

Note: Blender decimate modifier is very slow on high res meshes, perhaps it is better to write an own function

[Theverat]

In my opinion you can directly write the PLY export function in pyluxcoreforblender, don't waste time on a Python version. Python is fine for small meshes, but obviously the proxy system will be only used on very heavy meshes, otherwise it's not worth the drawbacks (can no longer edit the mesh, can only link/append when the path is absolute, etc.).

[neo2068]

I implemented the PLY export with the existing functions of pyluxcore, i.e. Scene.DefineBlenderMesh() and Scene.SaveMesh().

[Theverat]

Ah, nice, I forgot SaveMesh existed. So you create a luxcore scene in an operator's "exec" method, define the mesh, save it, and throw away the scene?

[neo2068]

Yes, exactly.

[Theverat]

I made some improvements, hope I did not break anything.

[Theverat]

The operator now supports FONT, CURVE, SURFACE and META. (It also skips/restores objects where to_mesh did not create any faces, like for "helper curves").

[neo2068]

Sorry for the delayed Response and thanks for your work. Currently, we are renovating our flat and I have very little time to work on the project. Additionally, I have to use my notebook with Ubuntu (because my windows desktop PC isn't available) which brings other problems during compilation.

Michael

[Eneen]

I'd like to add Indigo renderer workflow here as from my observations it's designed in best possible way.

1. In contrary to vray and renderman proxies are connected to mesh not to object, so it's possible to assign proxy mesh to any possible mesh and easily replace meshes using blender linking. It's really, really useful to work this way because if you want to replace bunch of trees with different type but you would like to keep positions you just invoke linking and then just rename objects.
2. You can create any possible simple mesh, even not related to final object, no GUI needed.
3. You can keep proxies in separate blend file and then just link mesh to main file. It's very easy to change, swap and replace models this way as you don't need blender proxies or group instances just mesh (with proxy info).
4. Indigo writes it's own .igmesh proxies that contains info about assigned materials (names). Materials that are assigned to objects are automatically passed to proxy (name of material matters), so it's possible to have materials inside scene or inside scene containing decimated mesh and it's easy to work with external materials this way

Here is link to my proxy workflow: https://www.indigorenderer.com/forum/viewtopic.php?t=14056

I can provide screenshots how it's done in UI, but generally speaking it's just path to proxy in mesh properties, that's all.

[Theverat]

That sounds very reasonable, thanks for the input!

[Eneen]

@neo2068 @Theverat here is my forum post regarding solution I've written about: https://forums.luxcorerender.org/viewtopic.php?f=5&t=9&start=660#p17782 I can help with testing/bugreporting.