Sprite Packer tight packing algorithm is wasting a lot of space

Hey guys

Ive attached page two (p2) and page three (p3) of my atlases. The omitted first page looks a lot like the second page, so it was left out for brevity.



Fortunately, this issue is pretty clear just by looking at the two screenshots. While the pages are clearly a little bit optimized, they are very far from optimal. The page (p3) with many small sprites could easily fit in the gaps of my other pages (p2 and omitted p1). While we use a custom packer policy, the issue occurs regardless of what packer policy is used.

Fortunately these are compressed with PVRTC which reduces the memory impact of the waste, but its still somewhat concerning since texture memory is our biggest bottleneck.

There are also other software packages that do a phenomenal job with packing like http://www.spriteuv.com/comparisonspritepacker and also prove that more efficient packing *can* be done.

Unfortunately, I cant use a third party tool since other tools will not use dynamic meshes to reduce fill rate and increase atlas sprite density. Those that DO use dynamic meshes end up using "mesh renderer" components which would be pretty incompatible with all the work we've already done.

Please help, Unity devs!

 

Funny, I was trying to find out why the Unity sprite packer was ... less than efficient. Seriously.

I have to pack everything into DefaultPackerPolicy for the uGUI. I don't understand why they'd make it so inefficient.

 

I'm as surprised as you, Yukichu. It's actually a really major problem considering that mobile devices have very limited memory compared to PCs.

I think it would be perfectly reasonable to provide an naïve packer if they allowed us to customize the algorithm, but since that is not possible, it's become a very serious issue that it is so inefficient.

The strange thing is that Unity's packer seems perfectly capable of handling the geometric calculations. One of my example sheets has dozens of sprites packed efficiently. It almost seems like its a bug that causes it to give up optimization prematurely.

 

I'm having the same issue in 5.3.2f1

 

@ColossalPaul

This was for an older version of Unity. The settings are all identical since they're set via code + grouped into atlases using an extended PackerPolicy (but I checked, and yes, the issue occurs with any PackerPolicy). The current version of Unity seems improved since my original post, though still not ideal as Joaobsneto confirmed.