Description of the problem

Hi,

It seems, three.js uses a WebGL extension (GL_EXT_shader_texture_lod) without checking whether it's supported first. To reproduce the problem, do the following:

Open up this link in a mobile firefox browser: (I have android, but I believe it might be the same for iOS as well).

If you switch to a PBR model, it won't appear in the scene. If you switch to another kind of model, it will appear just fine. Based on this, I believe, it has something to do with PBR.

I connected my phone to the firefox webIDE, and the console outputs the following message when the problem occurs:

Three.js version

• Dev
• r91
• ...

Browser

• All of them
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• macOS
• Linux
• Android
• iOS