Conversion backwards

[SavAct]

Is it possible to convert from BPMX and BVMD back to PMX and VMD?
Some users are concerned about their future support/compatibility. However, if they can be converted back at any time, there would be no reason to avoid using them.

[noname0310]

The absence of a reverse conversion is intentional.

Most MMD assets do not allow for secondary distribution as is. In this case, it may be helpful to convert the MMD asset to BPMX or BVMD for browser use.

But if I provide the reverse conversion, this becomes meaningless.
Therefore, the inverse conversion will not be implemented in the future.

What you do with BPMX and BVMD is up to you, but it's not a good idea to expose them to your users. There are already so many 3D asset file formats out there, and no one wants to deal with one more.

[SavAct]

Most MMD assets do not allow for secondary distribution as is. In this case, it may be helpful to convert the MMD asset to BPMX or BVMD for browser use.

I don't understand the reasoning here. Based on my experience with models where creators prohibit redistribution, converting and distributing the converted format wasn't permitted either.

Would converting to glTF be a better option?
Though I expect this would make it incompatible with VMD animations.

(I noticed that a gzipped BPMX file is roughly the same size as a glTF file of the same model.)

[noname0310]

I don't understand the reasoning here. Based on my experience with models where creators prohibit redistribution, converting and distributing the converted format wasn't permitted either.

In fact, the motion data I'm using in the demo in the readme.md is authorized because I've transformed it into a specific format (BVMD) that other tools can't read.

Would converting to glTF be a better option?

glTF is supported everywhere, you can just put it in blender and it will load. But BPMX doesn't support any other tools, because no one has implemented the loader.

And in order to convert the data in PMX as losslessly and efficiently as possible, you can't use another format like glTF.

To be specific, glTF has a specification for representing skeletons like PMX, but it does not support the weight parameters that MMD supports. This is where the losses occur in the conversion.