New Exposure and Lighting Defaults (and calibrate examples)

[cart]

Objective

After adding configurable exposure, we set the default ev100 value to 7 (indoor). This brought us out of sync with Blender's configuration and defaults. This PR changes the default to 9.7 (bright indoor or very overcast outdoors), as I calibrated in #11577. This feels like a very reasonable default.

The other changes generally center around tweaking Bevy's lighting defaults and examples to play nicely with this number, alongside a few other tweaks and improvements.

Note that for artistic reasons I have reverted some examples, which changed to directional lights in #11581, back to point lights.

Fixes #11577

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Changelog

• Changed Exposure::ev100 from 7 to 9.7 to better match Blender
• Renamed ExposureSettings to Exposure
• Camera3dBundle now includes Exposure for discoverability
• Bumped FULL_DAYLIGHT and DIRECT_SUNLIGHT to represent the middle-to-top of those ranges instead of near the bottom
• Added new AMBIENT_DAYLIGHT constant and set that as the new DirectionalLight default illuminance.
• PointLight and SpotLight now have a default intensity of 1,000,000 lumens. This makes them actually useful in the context of the new "semi-outdoor" exposure and puts them in the "cinema lighting" category instead of the "common household light" category. They are also reasonably close to the Blender default.
• AmbientLight default has been bumped from 20 to 80.

Migration Guide

• The increased Exposure::ev100 means that all existing 3D lighting will need to be adjusted to match (DirectionalLights, PointLights, SpotLights, EnvironmentMapLights, etc). Or alternatively, you can adjust the Exposure::ev100 on your cameras to work nicely with your current lighting values. If you are currently relying on default intensity values, you might need to change the intensity to achieve the same effect. Note that in Bevy 0.12, point/spot lights had a different hard coded ev100 value than directional lights. In Bevy 0.13, they use the same ev100, so if you have both in your scene, the scale between these light types has changed and you will likely need to adjust one or both of them.

[superdump]

Maybe worth noting as @fintelia wrote on discord that a the exposure was configurable, point/spot lights had one ev100 value and directional had another, so when using a combination of point/spot and directional lights in a scene you can’t just adjust the ev100 to achieve the old behaviour, you would have to adjust either all lights, or the ev100 and some lights.

[doonv]

Using Blender's default makes sense.

[superdump]

Code-wise it all looks fine. The reasoning behind the changes and new defaults is fine.

I do think we should clearly note how things worked before and how they work now to help people migrate their configurations and to think in the new way. Maybe that was done in the PR that introduced exposure.

[GitGhillie]

IMO the ambient light is generally too dark with this PR. Easiest to see in animated_fox but it's also in simple examples like 3d_scene.
0.12 vs this PR:

[GitGhillie]

Alien_cake_addict is also looking a bit grim

[rparrett]

Some notes on examples not mentioned yet:

custom_skinned_mesh - more ambient light?
gltf_skinned_mesh - more ambient light?
spotlight - more ambient light?
post_processing - too bright
resizing - super dim
minimising - super dim

[cart]

Maybe worth noting as @fintelia wrote on discord that a the exposure was configurable, point/spot lights had one ev100 value and directional had another, so when using a combination of point/spot and directional lights in a scene you can’t just adjust the ev100 to achieve the old behaviour, you would have to adjust either all lights, or the ev100 and some lights.

Good call. Added to the migration guide.

[cart]

Tweaked everything as suggested and bumped up the default AmbientLight intensity slightly (enough for it to more clearly register while still being reasonably subtle)

[GitGhillie]

LGTM