GLTFLoader: Add basic example.

[donmccurdy]

Fixes #13041.

[donmccurdy]

Demo: https://rawgit.com/donmccurdy/three.js/feat-gltfloader-helmet-example/examples/index.html?q=gltf#webgl_loader_gltf

Screenshot:

/cc @takahirox

[takahirox]

Personally I want the option to turn on/off envMap in scene.background because new users would be confused by what the model reflects.

[takahirox]

Not strong preference but I prefer

scene.add( gltf.scene );

because I'm really not sure how well function.apply style is known to JS (especially new) users.

If we don't wanna push gltf.scene to scene, the code would be like this?

or

while( gltf.scene.children.length > 0 ) {

    scene.add( gltf.scene.children[ 0 ] );

}

(a bit complex?)

[donmccurdy]

Sure ✅

[soljurami]

What is thst?

[donmccurdy]

Personally I want the option to turn on/off envMap in scene.background because new users would be confused by what the model reflects.

I don't think it's worth adding a UI toggle to change the background, since that's not the point of the example, but what about this?

[takahirox]

Looks good

[WestLangley]

@soljurami The description is at the top of the webpage.

@donmccurdy I would remove the background and add black or white fog if you want to keep the floor/shadow -- or remove the floor and set a black background. IMHO.

[takahirox]

@WestLangley Why you wanna remove the background? For the simplicity?

[looeee]

I think the background looks good here, and adds only a couple of lines of code. Even in these simple examples it's OK to demonstrate a couple of other basic techniques, such as adding floors, shadows, environment maps.

[WestLangley]

Why you wanna remove the background?

I think the example floor and background in combination are ugly. My suggestions were based on aesthetics only.

The first screenshot above looks very nice to me. Very professional. I'd go with that.

[takahirox]

I can understand. TBH I had the same feeling, the first one looked aesthetically better. (But the second one looks better as example.)

I still want background because of the reason I mentioned.

Removing floor? Do you folks think shadow is important in this example?

No floor.

No floor and grid.

[Mugen87]

If would pick the last option so no floor and grid.

[donmccurdy]

How about the floor+grid+sky of the first screenshot, with the skybox envMap replacing the park scene used before? I think if the reflections were just sky, rather than distinct trees, there's less potential for confusion. I do prefer the simple grid scene over any of the cubemaps, aesthetically..

[WestLangley]

Personally, I would not try to anticipate what new users would be confused by. I'd make the demo look as professional as possible.

I understand that what looks good aesthetically is a personal preference. I do not like the sky background at all. The first screenshot looks fine to me -- with either black or white fog. Just my opinion, though. :)

[mrdoob]

Don't you worry about it guys! I'll make sure it looks professional 😎

[mrdoob]

Thanks!

[takahirox]

I just realized I've misunderstood a bit.
I wanted background for showing that glTF 2.0 PBR material has environment map feature but I'm aware of that glTF 2.0 PBR material doesn't mention anything about environment map.

So the example looks fine.

Update: environment map would be in extension but no in core KhronosGroup/glTF#946

[mrdoob]

Alright, after 25b71ec I think it looks a bit more "professional" 😁