scene.background affected by tonemapping

[pikilipita]

images displayed on the background of the canvas using scene.background are affected by environment maps, in my case, they get darken.

I thought the purpose of the scene background was to display an image on the back of the canvas, but without the need of using an html tag.

In cases like the one below, I would expect the scene background not to be affected in any way by the scene lightning.

[WestLangley]

Can you please provide a live example to demonstrate your issue?

[pikilipita]

While doing the example, I found out that is it not directly the envmap that is affecting the scene background, but the:
renderer.toneMapping
and
renderer.toneMappingExposure
values

here's the example:
http://lune.live/scene_background/

[WestLangley]

OK, that makes more sense.

Is it acceptable to set a CSS background and set `WebGLRenderer( { alpha: true } ), instead?

[pikilipita]

I'm using scene.background to I can make screengrabs of the canvas that include the background.
That's how are generated all the thumbnails on this page:
https://xr.plus

if the image is outside of the canvas is will be excluded from the screengrab.

[WestLangley]

Got it.

Do you require tonemapping in your app?

renderer.toneMapping = THREE.NoToneMapping;

[pikilipita]

Ideally,
I would like to let users adjust the exposure of their environment map, like here:
https://threejs.org/examples/webgl_materials_envmaps_hdr.html

[mrdoob]

As discussed in #14827, backgrounds should be affected by tonemapping. #14856 aligned the behaviour to not be affected but we'll eventually implement the shaders bits so they're affected.