USD Hydra Render Engine #110765

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opened 2023-08-03 16:41:23 +02:00 by Brecht Van Lommel · 8 comments

This tasks lists remaining work for the Hydra render engine, as a follow up to #100892 and #104712.

High priority:

  • Solve OpenGL core profile warnings in console (#110474)
  • MaterialX export (#112864)

Missing features:

  • Material preview surface support in Hydra, sharing code with USD (#110836)
  • Meshes
    • Multiple UV maps
    • Per-vertex color attributes
    • Other attributes like velocity
    • Subdivision surface along with creases
  • Image caching
    • Properly update when image changes in Blender
    • For packed images, unpack instead of saving, is much faster (#110933)
    • Take into account multilayer, stereo, colorspace and other options
    • USD preview surface does not write packed or edited textures to disk
  • Hydra Storm is missing output sockets in compositor, registered Combined pass by default?
  • Hydra Storm seemingly can't read .tx files as in bistro/attic scenes
  • Create node parsing system for World light

Discrepancies between USD and Hydra (as seen in automated render tests):

  • Curves use as animation paths are incorrectly shown in USD
  • Legacy hair particles missing in Hydra (#114197)
  • For USD, child particles are missing
  • No transparent background with USD
  • Missing point clouds for both
  • No background to dome light export in USD
  • ... various other things not listed

Bugs:

  • Camera border in junkshop.blend is wrong in 3D viewport (#113376)
  • USD export has wrong transform for hair in junkshop
  • Blender OpenGL error in feature detection reported by USD (#110915)
  • Use PyC_UnicodeFromBytes should be used instead of PyUnicode_FromString for file paths.

Code cleanup (which should fix issues too):

  • Use BKE_camera_params API to simplify camera code and share more with rest of Blender (#114370)
  • Unify image writing code between USD and Hydra
  • Move _bpy_hydra implementation to python/ folder to avoid accessing private functions of that module?
This tasks lists remaining work for the Hydra render engine, as a follow up to #100892 and #104712. High priority: * [x] Solve OpenGL core profile warnings in console (#110474) * [x] MaterialX export (#112864) Missing features: * [x] Material preview surface support in Hydra, sharing code with USD (#110836) * [ ] Meshes * [ ] Multiple UV maps * [ ] Per-vertex color attributes * [ ] Other attributes like velocity * [ ] Subdivision surface along with creases * [ ] Image caching * [ ] Properly update when image changes in Blender * [x] For packed images, unpack instead of saving, is much faster (#110933) * [ ] Take into account multilayer, stereo, colorspace and other options * [ ] USD preview surface does not write packed or edited textures to disk * [x] Hydra Storm is missing output sockets in compositor, registered Combined pass by default? * [ ] Hydra Storm seemingly can't read .tx files as in bistro/attic scenes * [ ] Create node parsing system for World light Discrepancies between USD and Hydra (as seen in automated render tests): * [ ] Curves use as animation paths are incorrectly shown in USD * [x] Legacy hair particles missing in Hydra (#114197) * [ ] For USD, child particles are missing * [ ] No transparent background with USD * [ ] Missing point clouds for both * [ ] No background to dome light export in USD * [ ] ... various other things not listed Bugs: * [x] Camera border in junkshop.blend is wrong in 3D viewport (https://projects.blender.org/blender/blender/pulls/113376) * [ ] USD export has wrong transform for hair in junkshop * [ ] Blender OpenGL error in feature detection reported by USD (#110915) * [x] Use `PyC_UnicodeFromBytes` should be used instead of `PyUnicode_FromString` for file paths. Code cleanup (which should fix issues too): * [x] Use `BKE_camera_params` API to simplify camera code and share more with rest of Blender (https://projects.blender.org/blender/blender/pulls/114370) * [ ] Unify image writing code between USD and Hydra * [ ] Move `_bpy_hydra` implementation to `python/` folder to avoid accessing private functions of that module?
Brecht Van Lommel added the
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Render & Cycles
labels 2023-08-03 16:41:23 +02:00
Brecht Van Lommel added this to the Render & Cycles project 2023-08-03 16:41:25 +02:00
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Is there a plan for sharing geometry export code between Hydra and USD export? I'm noticing some differences right now-- for example that we use the mesh triangulation for Hydra but N-sided faces for the USD exporter. I imagine some of those differences might persist, but a lot of the code would be the same.

Is there a plan for sharing geometry export code between Hydra and USD export? I'm noticing some differences right now-- for example that we use the mesh triangulation for Hydra but N-sided faces for the USD exporter. I imagine some of those differences might persist, but a lot of the code would be the same.
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@HooglyBoogly that's what I asked for when reviewing this, but it seems difficult. See various comments in the code review.

Both the API and data are different. For example Hydra expects the mesh to be split into submeshes by material, and has an API that queries various attributes on demand rather than exporting everything. I think Hydra does not handle n-gons, except when using subdivision surfaces which is not implemented yet.

I think for geometry export specifically, the best we can probably do is to refactor the code to make its structure, names and behavior more consistent. There might be a bit of code that can be factored out and shared, but not much I think.

@HooglyBoogly that's what I asked for when reviewing this, but it seems difficult. See various comments in the code review. Both the API and data are different. For example Hydra expects the mesh to be split into submeshes by material, and has an API that queries various attributes on demand rather than exporting everything. I think Hydra does not handle n-gons, except when using subdivision surfaces which is not implemented yet. I think for geometry export specifically, the best we can probably do is to refactor the code to make its structure, names and behavior more consistent. There might be a bit of code that can be factored out and shared, but not much I think.

@brecht please add this to the list #110915

@brecht please add this to the list https://projects.blender.org/blender/blender/issues/110915
Author
Owner

@DagerD I added it now, and also gave you the permission required to edit the issue description yourself for future things.

@DagerD I added it now, and also gave you the permission required to edit the issue description yourself for future things.

Hey hey, I am new to the blender dev space, sorry if this is the wrong place to put my question.

Is there currently support for color attributes such as displayColor being translated to primvars or is that something this issue aims to cover? I imported Pixar's "Kitchen Set" scene into blender, and I noticed that the displayColor is being set as a vertex attribute; however, when using the Hydra Storm renderer, I don't see the colors set by displayColor when rendering (this is the same when using a custom render delegate).

Hey hey, I am new to the blender dev space, sorry if this is the wrong place to put my question. Is there currently support for color attributes such as `displayColor` being translated to primvars or is that something this issue aims to cover? I imported Pixar's "Kitchen Set" scene into blender, and I noticed that the `displayColor` is being set as a vertex attribute; however, when using the `Hydra Storm` renderer, I don't see the colors set by `displayColor` when rendering (this is the same when using a custom render delegate).
Author
Owner

@Elijah-Nicol that's "Per-vertex color attributes" in the list of missing features. I'm not sure if some other changes will be needed to make Storm use those colors or if it being named displayColor will be enough.

@Elijah-Nicol that's "Per-vertex color attributes" in the list of missing features. I'm not sure if some other changes will be needed to make Storm use those colors or if it being named `displayColor` will be enough.

@brecht I thought that was the case, just wanted to check! Do you know when the task of implementing "Per-vertex color attributes" will commence?

@brecht I thought that was the case, just wanted to check! Do you know when the task of implementing "Per-vertex color attributes" will commence?
Author
Owner

I don't have a timeline, that one will be hopefully be solved before 4.0 is out.

I don't have a timeline, that one will be hopefully be solved before 4.0 is out.
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