Recommendations for matching rendering in Bevy and Blender?

[bcolloran]

Hi all, I'm relatively new to 3d rendering, and I have a newbie question that I suspect a lot of other folks might have as well, so I'm hoping we can start a thread to collect the wisdom that the bevy community has gathered about aligning rendering between Blender and Bevy.

So, the question/topic is: Does anyone have beginner-friendly recommended workflows and/or settings that you have used to get the render output in Blender pretty close to what you'd see in Bevy? For my own purposes, I'm don't need perfection, but the fiddling I've done so far leaves much room for improvement.

My high level workflow objective is to be able to do my 3d work in Blender and have the GLTF files I import into Bevy look basically the same -- for me, there is a lot of value in doing high feedback iteration in blender without needing to make round trips to adjust things. I think I'd like to have a set of settings and constraints for both the Blender and Bevy sides that I can basically get set up once, and will thereafter allow me to do all of my visual work on the Blender with pretty high confidence that whatever I cook up in Blender will look basically the same without having to make additional adjustments on either side. I'm very willing to work within constraints to accomplish that, I just don't know what those constraints should look like, or what a good baseline setup might look like for each side.

(And for my use case while I'm learning, I intend to limit my scope to relatively simple low-poly models, though I'd like to play with lighting effects some. However, I'd be happy for anyone to share their experience with regard to realistic AAA-style graphics workflows between Blender and Bevy, as I'm sure that would be of general interest to the community.)

Some particular things I'd love tips on include:

• Which if any of Blender's render engines would be the best baseline on which to match Bevy's rendering?

  • The AI tells me Cycles doesn't support bloom. Is Eevee a better choice in that regard?

• And regarding bloom: I can live without it if it's too hard to get it to match, but I'd really like to use it if possible. Any recommendations on that front? I may be looking in the wrong place, but the bloom settings I see for Eevee (threshold, Knee, Radius, Color, Intensity, Clamp) don't obviously correspond to the options in
  Bevy (intensity, low_frequency_boost, low_frequency_boost_curvature, high_pass_frequency prefilter_settings: {...}, composite_mode).

• Any recommendations on materials+shaders? I know I can't cram an arbitrary Blender shader graph into a GLTF and hope for it to work, but are there parts of Blender's material+shader model can be straightforwardly exported to GLTF and rendered with roughly the same output in Bevy?

  • For some reason, I have gotten it in my head that Principled BSDF materials are pretty well supported. Is that at all correct? Are there parts of Principled BSDF that aren't supported?
  • Are there other material models that would be easier to set up for a good match between Blender and Bevy?

• I'm already using the tonemap Tonemapping::BlenderFilmic in Bevy. Anything else to be aware of regarding tone mapping?

• Matching lighting:

  • for mapping Blender "sun" lights to Bevy directional lights (I think this is the correct equivalence), I've tried converting from Blender's "strength" in W/m^2 to Bevy's illuminance in lux using the approximation 1.000 W/m² = 683.0 lumen/m² = 1lux from this page https://blendergrid.com/learn/articles/cycles-physically-correct-brightness. This is not giving entirely satisfactory results (looks much dimmer in Bevy. I could do trial and error, but if someone has a working conversion formula that woudl be much easier :-)
  • I'm not really sure how to approximate Bevy's AmbientLight in Blender. I can set a solid color background in Blender > Scene > World > Surface and fiddle with it's strength to get ambient light-like effects, but strength doesn't appear to have units, and neither does AmbientLight's property brightness, so I'm not sure how to do a consistent conversion there. Anyone have a working recipe for this?

I'll also say: since I'm new to this area, I don't know what I don't know -- I'm open to hearing that I'm thinking about this wrong, or asking the wrong questions! :-) And If folks have links or resources that have been helpful to them, please post here as well.

Thanks!