Support shadow intensity

[WestLangley]

As proposed in #8238.

The shadow intensity (darkness) can be changed without affecting the overall illumination of the scene.

This implementation adds a single uniform, renderer.shadowIntensity, that takes a value in [ 0, 1 ], defaulting to 1.

The approach works with (Gouraud) MeshLambertMaterial -- whose shadows are an approximation -- and it also works with the other built-in materials, where shadows are implemented correctly as the absence of light. (MeshLambertMaterial does not accommodate a per-light shadow intensity.)

I can add docs later if this is merged.

[sunag]

I think that for a more customized scene it should be per light light.shadow.intensity like Unity
https://docs.unity3d.com/Manual/ShadowOverview.html

[WestLangley]

I think that for a more customized scene it should be per light light.shadow.intensity

I do not think a per-light shadow intensity is possible with MeshLambertMaterial. It is possible for the other materials.

/ping @bhouston It the capability to control shadow intensity a worthwhile addition in your view -- or too hacky?

[WestLangley]

Closed due to lack of interest.

[iangilman]

I'm definitely interested! I'm not qualified to review the patch, but I'd use it if it landed…

[WestLangley]

For a workaround, you can use two lights: light1 and its clone:

var shadowIntensity = 0.5; // between 0 and 1

var light2 = light1.clone();
light1.castShadow = true;
light2.castShadow = false;
light1.intensity = shadowIntensity;
light2.intensity = 1 - shadowIntensity;

[iangilman]

Wow, that's brilliant in its simplicity! I wrestled with this problem for a bit and that solution never occurred to me. Thank you!

[Mugen87]

Closed due to lack of interest.

I think modulating the shadow intensity is something desirable for the library. I vote to reopen the PR and merge it with proper documentation.

[stevensanborn]

My issues with shadows are on the mesh level and would like to see it there. For instance a mesh with 10% opacity should not have a full shadow.
mentioned here

[manoj382]

For a workaround, you can use two lights: light1 and its clone:

var shadowIntensity = 0.5; // between 0 and 1

var light2 = light1.clone();
light1.castShadow = true;
light2.castShadow = false;
light1.intensity = shadowIntensity;
light2.intensity = 1 - shadowIntensity;

Saved me a lot of heartache. Thanks!

[Mugen87]

Closed due to lack of interest.

@WestLangley Modulating shadow intensity or darkness for artistic purposes is a feature request that repeatedly comes up (latest request from the forum). The workaround via lights provides a solution but it would be easier and more intuitive to configure a property per light shadow as suggested in #14087 (comment). Now that MeshLambertMaterial has been refactored and uses per-fragment lighting, there should be no blocker anymore (MeshGouraudMaterial from the addons should not support this feature).

I have implemented this feature in Mugen87@65510a7 and it can be tested with this link:

https://rawcdn.githack.com/Mugen87/three.js/65510a73b201b29cdf2714710feb773f227c90d0/examples/webgl_lights_hemisphere.html

Would you support this change?

[WestLangley]

Would you support this change?

Yes. I support adding shadow intensity for artistic purposes, as I did in #8238.

Please note that shadow intensity should take values in [ 0, 1 ]. Your example allows values larger than that, and the example should be corrected.