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Added documentation explaining the difference between lumens and luxes #11551

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merged 2 commits into from
Jan 27, 2024

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NthTensor
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Objective

Solution

  • Describe the difference between lumens and luxes, and why some lightsources use one and some the other.

@alice-i-cecile alice-i-cecile added C-Docs An addition or correction to our documentation A-Rendering Drawing game state to the screen labels Jan 26, 2024
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@alice-i-cecile alice-i-cecile added the S-Ready-For-Final-Review This PR has been approved by the community. It's ready for a maintainer to consider merging it label Jan 27, 2024
@alice-i-cecile alice-i-cecile added this pull request to the merge queue Jan 27, 2024
Merged via the queue into bevyengine:main with commit 8f25805 Jan 27, 2024
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@stepancheg
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Lux is used here instead of lumens because a directional light illuminates all surfaces more-or-less the same way (depending on the angle of incidence). Lumens can only be specified for light sources which emit light from a specific area.

Technically more correct explanation might be something like this:

... because for infinitely far directional light source, illuminance in lumens would be infinite which is practically useless.

@stepancheg
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more-or-less the same way (depending on the angle of incidence)

This can be rephrased like:

amount of light projected onto the surface depends only on the angle between the surface and the light direction, but not on the position in space.

@NthTensor
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Those would probably have been better. Do you feel they are important enough for me to open a follow-up?

tjamaan pushed a commit to tjamaan/bevy that referenced this pull request Feb 6, 2024
bevyengine#11551)

# Objective

- Fix bevyengine#9809

## Solution

- Describe the difference between lumens and luxes, and why some
lightsources use one and some the other.
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Improve lightight source light values documentation
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