Add Background.from_color

[almarklein]

Intro

To avoid blending issues (as in #724) it should be recommended to use a background in most use-cases. But creating a simple uniform background is currently a bit verbose:

scene.add(gfx.Background(None, gfx.BackgroundMaterial("#000")))

This is because the Background has the same geometry+material args as all world objects (except Scene and Group). I value that consistency, but it's also annoying to write out.

Alternative options

One option could be to drop the Geomety arg. But that's still pretty long. And it creates a problem when at some point we get a new kind of background that does need geometry.

scene.add(gfx.Background(gfx.BackgroundMaterial("#000")))

Another option is to allow something like this. I like the brevity, but documenting this is a bit awkward, I don't think this level of dynamic arguments works well here. Also what about a gradient?

scene.add(gfx.Background("#000"))

So what I came up with is this. A bit longer than the previous, but in return its explicit and unambiguous.

scene.add(gfx.Background.from_color("#000"))

Tasks

• Agreement on this proposal.
• Update examples that currenly use a color background.

[panxinmiao]

How about adding a background property to the scene?

Its value can accept Color, Image, Texture(CubeTexture) and Background, and pygfx will automatically handle the conversion.

With this, we can use the syntax scene.background = (0, 0, 0)

[almarklein]

@panxinmiao That is an interesting idea, which is also discussed in #582 (and other issues linked therein). A decision about that has not been made yet. We want to iron out other parts of the API first. But for the time being we prefer to keep the Scene no more than a group object.

The current PR also does not exclude that path, if we want to go that direction later.

[almarklein]

To add to that, I really like scene.background = 'red', but if we go that path, we should consider other properties (lights, clipping planes, etc.) too, and that's a pretty profound API change.

[Korijn]

I'm not really a fan of scene.background... I prefer API consistency