Examples: Update FBXLoader examples to .outputEncoding = sRGBEncoding

[donmccurdy]

Related issue:

• Loaders: Ensure all loaders properly label and convert color textures and colors to sRGB / Linear correctly #23283

Added THREE.ColorManagement.legacyMode = false only where helpful to preserve the original look. In other cases I think the changes to the image are correct.

[epreston]

I've been wondering about that. Will both Color and ColorManagement continue to export SRGBToLinear ? Is it more future proof to import from ColorManagement ?

[Mugen87]

Don't we need some changes in FBXLoader first before doing this, see #23283 (comment)?

[donmccurdy]

Will both Color and ColorManagement continue to export SRGBToLinear ? Is it more future proof to import from ColorManagement ?

Although ColorManagement.js exports SRGBToLinear and LinearToSRGB, we don't export those functions from the three.js top-level module. Userland code will have to access them through other methods, like the THREE.Color API. It's also an option to do this...

THREE.ColorManagement.convert( color, 'srgb', 'srgb-linear' );

... but the THREE.Color API is more stable at this point; there is no reason to switch. I would probably consider convert(...) to be an internal API at least for now.

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Don't we need some changes in FBXLoader first before doing this, see #23283 (comment)?

I'd missed that, thanks! Currently FBXLoader color manages textures, but nothing else. So we're in a limbo where it's only half correct. I don't think that updating the examples to use .outputEncoding = sRGBEncoding makes things any worse, but we should definitely finish the changes to FBXLoader as well.

[donmccurdy]

Let's go ahead and do the changes described by #23283 (comment) too. I noticed that Blender has a choice when exporting FBX of whether the vertex colors are linear or sRGB. The default is sRGB, and I don't know that we can detect which was chosen, so I've assumed they're sRGB here.

@looeee as FYI, meant to preserve the look and appearance of FBX models under outputEncoding=sRGBEncoding.

[Mugen87]

Since the color maps already set .encoding = sRGBEncoding;, this PR is complete now. Merging.