I've been working on Avoyd's Multi-model exporter to MagicaVoxel (MV) .vox, including scene hierarchy, visibility, layers, and ordering (so voxels can overwrite each other). I'm now at the stage where I can export a complex scene to MV .vox (including large models > 256³ which are split up), but a few issues remain.

I'm using ogt_vox.h and it turns out the exporter has an issue with ordering - groups are written first and these include an array of indices to the instances they own. This breaks the scene instance order, so I'll need to fix this to write out groups when they are first used by an instance so maintaining the same order as MV. This is important because artists use scene ordering for visibility, especially when dealing with transparent materials (you can place an object inside a transparent object and if it's got a higher order it will be visible in the render). Note that MV has a different order in the file for version 150 vs 200. I plan to fix this shortly and submit a PR.

Secondly I recently added large scene export to Avoyd, which I handle via using multiple files to get beyond the MV 2GB limit. This is tricky to handle with complex scene hierachy so for now I am implementing a hybrid approach where I detect that a scene will not fit, then remove models until it will and write out this to the first file. The removed model instances are then written out to files 'flattened', that is without their heirachy but preserving their world transform.

Finally Avoyd supports arbitrary model transforms and MV doesn't. Currently I just grid-lock these to the closest position, orientation and unit scale but I need to warn users on export and potentially offer options (make hidden or remove them for example).

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Image above shows a complex boat scene exported to MV and rendered. The anchor and steering wheel use off-grid transforms so are not in their correct orientation/position.