[WIP] Tight Mesh Sprites - Configurable and Optimized

UPDATE: SpriteSharp has since been released and is available on Asset Store:
https://www.assetstore.unity3d.com/en/#!/content/37599
Go check it now

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Hi everyone,

as you probably know, sprites in Unity have two different options for sprite meshes - Full Rect and Tight.
Full Rect is nothing more than a single quad, which is fine, but results into huge overdraw, as seemingly empty regions of the sprites are actually still rendered, consuming the GPU fill rate, which is especially in short supply on mobile platforms. Tight meshes avoids this issue by constructing a mesh that follows the contours of the sprite based on the texture alpha. This is a really awesome feature of 2D in Unity, the only problem is... there is no way to control the generation of the sprite mesh, and quite often Unity generates absurdly high-poly meshes, pretty much defeating the whole performance gain from this optimization This is long-known issue, but apparently, there is no fix to this day:
http://forum.unity3d.com/threads/tight-sprite-mesh-generating-terrible-meshes.247102/
http://issuetracker.unity3d.com/issues/triangle-and-quad-sprites-can-generate-far-too-many-vertices

But when Unity 5 was released, I've noticed a new API that allows overriding the sprite meshes. And so the work began to give better control over sprite meshes. Here are a few current results (Unity mesh on the left, mesh generated by my tool on the right):

The generated mesh is generally much cleaner, with less triangles to render.

You can change the mesh settings per-sprite, even if sprites are coming from the same texture. It also integrates nicely into Inspector, allowing to preview the new sprite mesh:


It won't work with Unity 4, as the API only became available in Unity 5, but I believe that's not a problem for most people.

I am thinking about putting this on the Asset Store for maybe $10. Does this seems like a fair price to you? It's pretty much finished and just needs a lot of polish, but probably you guys have some ideas on what can be added.

All things considered, what do you think about this?

 

Great work! Keep it up.

 

Wow, I'm impressed. Nicely done.

 

Added multi-sprite editing, apply/revert buttons and undo/redo functions, so now it pretty much looks and feels like it has always been there

 

What is your timeline for getting this in the Asset store?

 

Somewhere at the middle of May.

 

I'm very surprised Unity engineeres not proposing some option really

 

Well, AFAIK, they are not doing that deliberately, with the justification that the amount of vertices generated by Unity is never to cause problems even on mobile platforms. And while vertex processing generally takes much less time draw pixel processing, that is obviously not entirely true:
1) If you are drawing a lot of sprites, the difference between 1000 triangles and 100 triangles per sprite is increasingly big.
2) Also, SpriteRenderers are only batched up to a certain amount of polygons (somewhere like 5k), because they are batched on the CPU, and there is an overhead of doing that. So decreasing the polygon count could in fact decrease the amount of draw calls and CPU load.
3) Unity doesn't takes into account that sprites can actually be scaled, because, well, it has no knowledge about how sprites will actually look in game. There is no point of making highly-tesselated mesh for an object that typically takes a small amount of screen space anyway. That's why a manual control is required.

 

Have you considered an option for maximizing opaque / minimizing semitransparent areas?

 

There is an "alpha tolerance" parameter that controls just that. Basically, all pixels with alpha lower than the alpha tolerance value are considered opaque and are included to the mesh.

 

I'm talking about using two submeshes/sprite renderers. It's worth doing if the opaque areas cover a lot of screen area. I don't know if it's even feasible in Unity yet.

 

Tomorrow is the middle of May



Looking forward to release

 

Ah, makes sense. I believe this can be done, but at the very least this'd mean doubling the amount of sprites, since mesh is generated per-sprite, so that'd be a bit of inconvenience. But otherwise this is a great idea, I'll probably try to implement this in some future update.

Well, I said "somewhere at the middle of May" I've just came back home from a trip and hope to release it next week.

 

This is such a neat tool!

 

OK everyone, I've sent the first version to the Asset Store for approval It usually takes around a week for them to accept a new asset, so hopefully it all goes smoothly.

 

Bored from waiting the approval, I've created a new announcement thread for SpriteSharp here:
http://forum.unity3d.com/threads/spritesharp-sprite-mesh-optimizer.327997/
Check it out for some nice images, and please post any replies there now
Thank you everyone for your support!