TSL: shadows

[sunag]

Description

The shadows node allows shadows to be used as masks for effects.

import { output, shadows } from 'three/tsl';

material.outputNode = output.add( shadows );

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	692.22 171.45	692.22 171.45	+0 B +0 B
WebGPU	825.46 222.91	825.57 222.93	+104 B +20 B
WebGPU Nodes	824.58 222.7	824.68 222.72	+104 B +27 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	464.58 112.26	464.58 112.26	+0 B +0 B
WebGPU	545.63 147.78	545.69 147.79	+62 B +11 B
WebGPU Nodes	501.51 137.48	501.57 137.49	+62 B +15 B

[Makio64]

@sunag Asking for my personal understanding :
1 : this allow us to get the shadow casted on the mesh and use it in the material for example for adding a dithering or modifying the color of the shadow on the material ( in the fragment shader level ) ?
2 : this allow us to modifying the shadow texture before its send to the material ( for example to add blur on it )

[sunag]

We have some API features aimed at different purposes.

• material.shadowNode -> Allows you to change the opacity and color of the shadow, or procedural effect in TSL.
  https://threejs.org/examples/?q=shadow%20opacity#webgpu_shadowmap_opacity

• material.outputNode = output.add( shadows ) -> Allows you to obtain the shadow at the output level, useful for creating special effects based on the shadow, such as using the shadow as a mask to project another node in the shadow area in the target material. Note that add() can be replaced by another mathematical operation here.

• light.shadow.filterNode -> Here customizing the shadow filter, such as using PCFSoftShadowMap or creating your own, is the appropriate place to soften the shadow.

[Makio64]

Thanks for clarifying! Just to be sure :

Shadows render pass :
material.shadowNode : how the material project his shadow into the shadowmap during the rendering of lights
light.shadow.filterNode : filter apply during the rendering of the lights ( blur etc.. )

Scene render pass :
shadows : the value of the compile shadows at the pixel level ( in the fragment shaders ).

So when you do :
material.outputNode = output.add( shadows ) it add the shadow value over the output which already have shadows ?
If I want to rewrite how the shadow is rendered on my mesh for example with a very low opacity for a 'GhostMaterial' how to do so ( I originaly thought it was the purpose of the shadowNode. ) ?

Maybe shadowNode is little bit confusing and a castShadowNode and a receivedShadowNodewould be easier or maybe its just me ?

[sunag]

Maybe shadowNode is little bit confusing and a castShadowNode and a receivedShadowNodewould be easier or maybe its just me ?

castShadowNode seems like a good name 👍

[sunag]

@Makio64 I think this will be possible now, the suggestion was great and I updated the API.
#29840