solved DXT KTX WebGL Skybox Issues

[SneakySnave]

Hello. I'm having an issue creating a skybox with compressed ktx textures.

I've followed the instructions here, and have used the 2 bat scripts in conjunction with the PVRTexTool and ASTC tools. Note that I've used "D" for developer level quality.

cd my-directory-with-images
make-ktx-batch D
ktx-batch

That seems to have correctly generated the compressed files.

I then create the default skybox.

var available = ['-astc.ktx', '-dxt.ktx', '-pvrtc.ktx', '-etc2.ktx', '-etc1.ktx'];
var formatUsed = engine.setTextureFormatToUse(available);
console.log(formatUsed + ' textures');

...

var skyboxTexture = new BABYLON.CubeTexture("textures/skybox/gradient-sky/SkyGradient", scene);
scene.createDefaultSkybox(skyboxTexture);

Based on the console output, it seems to be attempting to load the texture format used "-dxt.ktx" at my root URL.

I'm testing in Chrome on a MacBook, but am getting the same error in Firefox and Safari "Error: Error status: 404 - Unable to load -dxt.ktx".

Any ideas?

Thanks for taking the time to read.

[GameMonetize]

Did you make sure to enable .ktx mime type in your wbe server?

[SneakySnave]

Thanks for the lightning quick response, @Deltakosh!

I believe so. I have this in my mime.types file

image/ktx					ktx

 

[GameMonetize]

so if you go to http://localhost:8888/-dxt.ktx there is an actual file ?

 

[SneakySnave]

No, there is no file at http://localhost:8888/-dxt.ktx

[JCPalmer]

I never had any cube textures to test.  I just made the same changes I did to 2d textures.  I think the reason might have something to do with that there is no "SkyGradient" file, maybe try a real file (which will be the fallback) like "SkyGradient_ng.jpg".

[SneakySnave]

Thanks for the clue! I think I found the problem. It looks like you cannot cascade load separate sides of a cube texture if you're using a compressed texture format.

I followed the call stack from my line "var skyboxTexture = new BABYLON.CubeTexture("textures/skybox/gradient-sky/SkyGradient", scene);".

Not using a compressed texture format leads to Engine.prototype.createCubeTexture, and the function call cascadeLoad at line 10578 below.

Using a ktx texture format leads to Engine.prototype.createCubeTexture, and the function call BABYLON.Tools.LoadFile at line 10535 below.

At line 10528 the rootUrl is changed to the engine.textureFormatInUse, which is "-dxt.ktx". Then BJS tries to load a file "-dxt.ktx", which doesn't exist.

Is there a reason you cannot load all the sides of a cube texture separately when using a compressed texture format?

[GameMonetize]

The basic reason is because it was initially built for dds which can contains cube texture.

CascadeLoad uses html img object to load the faces unfortunately so it is not compatible with ktx

[SneakySnave]

Ah, I understand. So if you're going to support multi platform ktx textures in your project, you must also use that for your skybox. You cannot mix and match.

Thanks, @Deltakosh!