LDrawLoader: Convert to linear colors when parsing models

[gkjohnson]

Related issue: --

https://raw.githack.com/gkjohnson/three.js/ldraw-linear-color/examples/webgl_loader_ldraw.html

Description

Semi-related to @donmccurdy's color space consistency efforts (#22346) -- all loaders should appropriately label texture color spaces, convert colors to Linear color space, and set the renderer output color space to sRGB. This PR does so for LDrawLoader.

From what I can tell these are the loader examples that still are not setting renderer.outputEncoding = sRGBEncoding on the page meaning they don't appropriately set the model color spaces for linear lighting calculations on load where I think the color space should be known at parse time:

• ColladaLoader examples
• FBXLoader examples
• IFCjs example
• OBJLoader examples
• SVGLoader (example logic only)
• Maybe: Vox, VRML, VTK, PCD, GCode

Here are some before and after screenshots. It seems to get rid of the blue specular look on the black pieces. The AT-ST line colors significantly darker now, as well, because tone mapping is being applied to Linear rather than sRGB values. I'm kind of on the fence about the change because while converting the colors to linear is more correct I kind of stylistically prefer some of the "before" screenshots better. Or maybe I'm just used to them. The spaceman blue definitely looks more like the real model now, though:

BEFORE	AFTER	AFTER w/o Tone Mapping

cc @WestLangley

[yomboprime]

I guess this PR is correct. Sorry but I don't know much about color spaces.

About the SVGLoader, I would say in that case it does not apply since the loader only parses the file but does not create Mesh or Material objects. Instead they are created afterwards by the specific application, based on path points and .userData, like styles. I think colors should be remain untouched by the SVGLoader.

BTW, I like more the new tones :-)

[gkjohnson]

About the SVGLoader, I would say in that case it does not apply since the loader only parses the file but does not create Mesh or Material objects. Instead they are created afterwards by the specific application, based on path points and .userData, like styles. I think colors should be remain untouched by the SVGLoader.

Oh yes I see now -- you're right. In that case then maybe the conversion should be happening in the example code itself.

BTW, I like more the new tones :-)

I think most of them look better -- the only one that looked odd to me were the particularly dark lines in the AT-ST example from the tone mapping.

[mrdoob]

Thanks!

[mrdoob]

From what I can tell these are the loader examples that still are not setting renderer.outputEncoding = sRGBEncoding on the page meaning they don't appropriately set the model color spaces for linear lighting calculations on load where I think the color space should be known at parse time:

• ColladaLoader examples
• FBXLoader examples
• IFCjs example
• OBJLoader examples
• SVGLoader (example logic only)
• Maybe: Vox, VRML, VTK, PCD, GCode

Should we create a new issue to keep track of this work?