Supporting other compressed texture formats (ETC2/PVR) for WebGL

Hello,

I know mobile is not officially supported, but since iOS (Safari) 11 and the latest Chrome for Android support webassembly we've ran a few tests and it may be feasible for us to allow some (few) mobile devices to use WebGL. A big blocker though to fully validate this is the DXT format that Unity uses for WebGL (obviously not supported on most mobile gpus resulting in decompression to uncompressed textures). We use asset bundles so it wouldn't be too hard for us to build different texture bundles for various devices, but at the moment these formats are not exposed to us under WebGL.

Thus we were wondering if PVR (iOS) and ETC2 (Android) formats could be added as possible compressed texture formats for WebGL. Again while mobile isn't officially supported, I think you'll have more interest on those platforms sooner rather than later and the ability to use different texture formats will be essential.

 

Support it strongly!

 

Yes, we are working on it now.
We are trying to help Unity WebGL migrate to mobile browsers and Facebook IG.

 

Maybe you can try this demo, https://www.mujigame.com/muji/samurai2/index.html
It can be played on Android and iOS.

 

We use our technologies to optimize Unity WebGL original version (emscripten version), actually, almost all of current Unity WebGL cannot work on mobile, because there are two major issues:
1. code size is huge (engine + game logic);
2. resources are huge (it is caused by emscripten memory file system I think);
Because memory usage exceeds the limitation on mobile, especially on iOS, Unity WebGL will crash, we rebuilt Unity WebGL original output by our compiler, redesigned the file system with our blocking technology based on cloud service, solved many issues in Unity output for mobile such as rendering, touch, even we modified il2cpp code to add bsd socket and multithreading support for online game, we call our system WEB-IR, I think it can help Unity WebGL move to real mobile very well.
Add more:
Texture compression format is another big issue, because it looks Unity WebGL only supports the formats for desktop browsers currently, but on mobile browser such as android chrome and iOS webkit, Unity WebGL has to decompress these textures by software, obviously, it is eating the time and memory space, it causes poorer performance and higher crash risk, whether more mobile WebGL texture formats can be supported such as pvrtc on iOS and astc/etc1 on Android?
And This game is Samurai2, the copyright belongs to the author MadFinger or their publisher, we just use it as a Demo to experiment.

 

So I'm bumping this thread again. I don't mean to beat a dead horse here, I'm quite confident Unity is working hard on mobile! However I just wanted to say I think the time to support ETC2 in addition to DXT should be sooner rather than later.

We're quite happy with how wasm performs on the last few versions of Android (i.e. Chrome on Android) even when decompressing our DXT textures. We seriously think we can start supporting Android in the (very) near future. As you can imagine a huge deal! Obviously I'd really like to avoid using uncompressed (decompressed dxt) textures and I also rather not develop a whole pipeline for "side-loading" (through UnityWebRequest) etc2 textures. I really think Android today is already a viable platform for Unity webgl. Maybe if iOS supported wasm it could too...

 

So I did a little more investigation into the subject and there are just a few things that I'll note (I'm sure you know most anyways):

• We still need PVR. I was hoping that we (as a community) could just get away with DXT (desktop) and ETC2 (mobile). But while the hardware obviously supports it, iOS only exposes PVR as a compressed texture format to WebGL (not even ETC1 either!). I confirmed this with my iPhone X on iOS 11.4.
  
  
• I firmly believe we should be using ETC2 and not ETC1 for Android. I understand there might be a desire to pick ETC1 to ensure the broadest level of support. But I'd counter with on WebGL they actually both have similar market share [ETC2: https://webglstats.com/webgl2/extension/WEBGL_compressed_texture_etc ETC1: https://webglstats.com/webgl2/extension/WEBGL_compressed_texture_etc1]. And let's face it, ultra-low devices that only support ETC1 (Mali-4xx) are not running Unity WebGL anytime soon. ETC1's lack of alpha support makes it significantly harder to work with in a content pipeline (extra shaders, extra textures, etc.). In this circumstance I think the negatives far outweigh the positives for ETC1 when compared to ETC2.
  
  
• While obviously I think the endgame should be to support DXT, PVR, and ETC2. I think adding ETC2 support should be given priority over PVR (if that's even applicable). As noted above we really like where Android is at the moment and are extremely confident we can make our currently existing product work with only minor caveats. iOS without wasm still needs some work (at the very least our current products won't work without some modification) thus I think the business opportunity there is lower (maybe you could just limit it to the latest iPads?). But in general, I'd highly recommend people to give Android wasm a look. Definitely a viable platform with just a little help from Unity imo.

 

So some good news for those who are a bit adventurous!!! It turns out Unity WebGL does support PVR/ETC2 "under the hood". I compressed a texture to PVR (outside of Unity) and "sideloaded" using Texture2D.LoadRawTextureData.

On my desktop computer:

On my iPhone X:




Some interesting opportunities have just opened up! Of course would be nice not having to sideload textures...

 

Well spoke too soon on ETC2...

My guess is Unity doesn't interpret the "WEBGL_compressed_texture_etc" or "GL_WEBGL_compressed_texture_etc" extensions as that device supporting ETC2. Bummer! Amusingly the "PVR build" works on Android devices that use Imagination Technologies GPUs (I guess not that surprising)...

 

No dice, I changed the code to:

Code (JavaScript):

1. var automaticallyEnabledExtensions = ["WEBGL_compressed_texture_etc1", "WEBGL_compressed_texture_etc", "OES_texture_float", "OES_texture_half_float", "OES_standard_derivatives", "OES_vertex_array_object", "WEBGL_compressed_texture_s3tc", "WEBGL_depth_texture", "OES_element_index_uint", "EXT_texture_filter_anisotropic", "ANGLE_instanced_arrays", "OES_texture_float_linear", "OES_texture_half_float_linear", "WEBGL_compressed_texture_atc", "WEBKIT_WEBGL_compressed_texture_pvrtc", "WEBGL_compressed_texture_pvrtc", "EXT_color_buffer_half_float", "WEBGL_color_buffer_float", "EXT_frag_depth", "EXT_sRGB", "WEBGL_draw_buffers", "WEBGL_shared_resources", "EXT_shader_texture_lod", "EXT_color_buffer_float"];
2. var exts = GLctx.getSupportedExtensions();
3. if (exts && exts.length > 0)
4. {
5.     GLctx.getSupportedExtensions().forEach((function(ext)
6.     {
7.         if (automaticallyEnabledExtensions.indexOf(ext) != -1)
8.         {
9.             console.log("extension IS enabled " + ext);
10.             GLctx.getExtension(ext)
11.         }
12.         else
13.         {
14.             console.log("extension NOT enabled " + ext);
15.         }
16.     }))
17. }

And it did print out:

But still shows unsupported:

Damn! I really thought that would do it too. I made a development build and tried to look through the code to determine how Unity checks supported texture formats (I suspect the underlining problem with ETC2 is something silly!), but I'm getting lost chasing function pointers around in the heap. I'll let you know if I make any other progress. I'll try ETC1 next (yuck no alpha) and see if I can get that working (and maybe ASTC if I'm desperate).

 

Well ETC1 and ASTC also both don't work. So I've only been able to get PVR working on iOS and Android. I'm wondering if I'm actually enabling those extensions "under the hood". I'll investigate a little more, but I think I'm hitting some roadblocks...

 

Any news?)

 

We went backwards, can't even load PVR on ios using my "trick" on newer versions of Unity. Still hoping one day...

 

Slight bump.

Is there any progress on this being supported officially? We have a WebGL scene that we would like to work on both Desktop Web/iOS Web and Android web and we are struggling with Texture decompression on iOS. kognito1 mentioned that the workaround doesn't work on newer Unity versions, could you let me know what version it does work on?

 

Another +1 for this.
We have a game that runs great on desktop WebVR / WebGl and crashes on Oculus Quest because of the forced DXT decompress / out of memory crash. If WebGL could support ETC2 or ASTC, we'd probably have the highest market share multiplayer VR game out there. But the DXT thing means no-go for mobile.

And Unity -- WebGL works for mobile! Very few mobile phones I've tried don't support the builds coming out of your pipeline. But these annoying little things really kill it. Literally just fix texture compression options and we'll have a AA competitive VR game built on your platform in WebVR

 

Yeah still the biggest challenge on mobile for us.

The last version of Unity where Texture2D.LoadRawTextureData worked with PVR textures was 2018.2 btw.

 

If you can see Safari console on iOS, you will see that PVR supported. I see that on Unity 2018.3.12f

 

Yeah that's just printing out all the WebGL extensions the browser supports. The issue isn't the browser (Safari), but Unity not enabling (or using correctly) the extension anymore.

 

OMG.

Instead, we can achieve the display of ETC textures, but not PVRTC. We expanded the export of ETC / PVRTC textures and loaded the corresponding resource packs according to different platforms when loading. Well, the test result was that the ETC1 texture can be displayed normally on Android phones, but it is black with PVRTC on IOS.

 

We also encountered the same problem, could you describe detail how to export and load ETC/PVRTC? Many thanks in advance.

 

when use unity 2020.3.25f1, and use crunch etc2 format,but at mobile phone its display
blurred screen，i only use sprite to test, i can support project. moblie phone support etc2 format， but why happen blurred screen，help。