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elringus / sprite-dicing

Cross-engine tool for lossless compression of sprites with identical areas
https://dicing.elringus.me
MIT License
1.35k stars 144 forks source link

Improve dices content hashing speed #19

Closed elringus closed 2 years ago

elringus commented 3 years ago

Currently, content hash for dices is generated via Unity's Texture.imageContentsHash, which requires creating and filling a texture per dice, which is inefficient: https://github.com/Elringus/SpriteDicing/blob/master/Assets/SpriteDicing/Editor/Processors/TextureDicer.cs#L93

If anyone have an idea on how to replicate the Unity's image content hashing in a way that even slightly different textures will have unique hashes, please share it here or create a pull request. I've already tried hashing color arrays by each item value and its index, but it's not working in some cases (eg, square in Assets/Examples/Atlases/Flat will have artifacts).

We could probably try Hash128.Compute, which accepts arrays in Unity 2020, but I want to keep compatibility with 2019.4 for the time being.

konistehrad commented 2 years ago

As 2019.4 is falling into the rearview, we can theoretically use HashUnsafeUtilities.ComputeHash128 for legacy compatibility, and use Hash128.Compute elsewhere. This will add a unique codepath, as well as a "must enable unsafe code" warning for 2019.4, but since that requirement is limited to editor-only code, perhaps this is a decent compromise in the name of backwards compatibility?

elringus commented 2 years ago

@konistehrad thank you for the info! I didn't know about HashUnsafeUtilities. It turns out Hash128.Compute in Unity 2020 is just a wrapper over that utility: https://github.com/Unity-Technologies/UnityCsReference/blob/master/Runtime/Export/Hashing/HashUtilities.cs#L58

The hack is now resolved in v1.6.

konistehrad commented 2 years ago

HA! Wow you're fast, very cool, and excellent work. 👍