I think it would be useful, for texture compression issues, allow Paper2D sprites to have more than 1 texture (1 for RGB and another one for alpha channel). This way all textures could be compressed with ETC1 for android.
I was wondering if there is any plan to make sprites more texture-compression-friendly.
If not, I could try to implement this myself and then I would like to hear your advice (in order to do something that at least could be profitable to more people, not just me).
I’d like to add general support for multiple textures on sprites. It won’t be specifically for Android texture compression, but with a custom material that pulls RGB from the first slot and A from the second, it could certainly be used for that (as well as for normal-mapped sprites, complex materials that need a mask texture, etc…).
I haven’t decided exactly how I plan on implementing it yet, but conceptually it’s not too bad:
Adding either an array of textures or a fixed set of additional textures to UPaperSprite
Transferring more than one texture from game thread to render thread in the various sprite/flipbook proxies
Adding a texture index/texture slot parameter to UMaterialExpressionSpriteTextureSampler
Extending the named texture replacement stuff in FTextureOverrideRenderProxy to replace more than one
Note: You can work around this now if your source assets are already atlased, you could create one material instance per atlas page that references the separate alpha texture as a non-sprite texture sample. (You could even do it if they aren’t atlased, but you’d have a plethora of loose one-off materials that might be annoying to work with).
[edit] I also just want to take a moment to both rue and lament the state of texture compression on mobile devices and the patents on texture compression that put everyone in the present situation.
Also thanks for the workaround, I really like it. Simple and easy to implement! I definetly can use it.
I have all textures atlased except the textures I use with UMG (which currently does not support atlasing and its a BIG pity). So yeah, It will work ! I guess at some point the implementation of sprite batching will push towards having less and bigger atlases right?
Paper2D: Add support for specifying additional textures for a sprite
This is useful for providing masks, normal maps, etc…
The position of the sprite in each additional texture must match the relative position in the Source sprite
Sprite texture sampler nodes can now be configured to point to one of the additional textures
Paper2D: Add name customizations for sprite texture slots, which are pulled from the default material (so you can tag a slot as ‘Normal Map’ or ‘Base Map’ and it will display that way in the Sprite Editor)
Appreciate that this is a very old post…
But is there any way to deal with image sequences in the additional slots? If I have an image sequence of 100 frames do I have to manually select each normal, roughness, emission etc. texture that I add to my sprite?
