SpotLightShadow: Added .focus property

[WestLangley]

This feature allows the user to set a focused spotlight shadow.

.focus is a value in [ 0, 1 ]. Default is 1.

Everything else just works -- spotlight shadows continue to auto-update, helpers work as expected, and it is backwards-compatible.

I'll update docs, etc., if there is support for this PR.

EDIT: docs updated

[WestLangley]

/ping @RemusMar

[Mugen87]

Nice! So @mrdoob has now the choice between a flag and simple float property :)

One minor disadvantage: Compared to autoFOV (#20147 (comment)), setting shadow.camera.fov would still have no effect.

[WestLangley]

setting shadow.camera.fov would still have no effect

setting shadow.camera.far also has no effect.

setting shadow.camera.near works, because it is not overwritten by the updatMatrices() method.

It is a bit difficult to understand what can be changed -- and what cannot.

[WestLangley]

Consequently, I prefer to consider that the spotlight shadow frustum is auto-set ( that is the intention, after all) , and to provide a focus property that tells the renderer how to auto set it.

[Mugen87]

It is a bit difficult to understand what can be changed -- and what cannot.

Yep, that's a bit unfortunate. Anyway, your argumentation is definitely valid. TBH, I'm not feeling strong about what solution will be merged. I'm just happy if we are able to avoid the LightShadow export! 😇

[WestLangley]

I'm just happy if we are able to avoid the LightShadow export!

And I'm happy I can focus the shadow. :-)

[RemusMar]

I'm just happy if we are able to avoid the LightShadow export!

Why?

SpotLightShadow: Added .focus property
.focus is a value in [ 0, 1 ]. Default is 1.

👍

[WestLangley]

Updated TS and docs.

Todo: update migration docs, I assume...

[WestLangley]

Added spotlight shadow .focus to the GUI in the spotlight example.

The demo clearly illustrates how the quality of the shadow is improved by focusing the frustum.

PR requires a rebuild.

[RemusMar]

The demo clearly illustrates how the quality of the shadow is improved by focusing the frustum.

There is a significant difference in this example as well:
https://necromanthus.com/Test/html5/testA_disco.html
(spotLight angle at 50, but shadow at 22.5)

[mrdoob]

Nice solution!

[mrdoob]

Thanks!

[mrdoob]

Actually, isn't shadow.focus a bit like camera.zoom?
Well, camera.zoom increases to reduce the frustum while shadow.focus decreases... 🤔

[WestLangley]

Yes. Users need to use this pattern, however:

spotLight.shadow.camera.zoom = zoom;
spotLight.shadow.camera.updateProjectionMatrix();

If you prefer, I can update to use .zoom, instead.

[RemusMar]

updateProjectionMatrix() is not quite cheap.
I use it here for the right mouse button:
https://necromanthus.com/Test/html5/testA_disco.html
Also, ZOOM for shadows sounds a bit "obfuscated".
I like the FOCUS approach (and I already updated many samples)

[mrdoob]

Okay, lets go with .focus 👌