WebGPURenderer: Manual Shadow Update Control via shadow.needsUpdate

[RenaudRohlinger]

Description
This PR allows to manually control the update of a shadow through the already available shadow.autoUpdate and shadow.needsUpdate properties.

Usage:

const dirLight = new THREE.DirectionalLight( 0xffffff, 10 );
dirLight.castShadow = true;
dirLight.shadow.autoUpdate = false;
dirLight.shadow.needsUpdate = true;

To demonstrate the feature, I updated the webgpu_shadowmap_opacity example:

Before:

After:

To ensure this feature works correctly, I had to account for the versioning of depthTexture. Without this, when the Renderer initialize the FBO in the first render loop, it updates the attached textures, leading to the incorrect shadowMap being bound to the meshes in subsequent renders.

This contribution is funded by Utsubo

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
685.1 kB (169.6 kB)	685.1 kB (169.6 kB)	+0 B

🌳 Bundle size after tree-shaking

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

Filesize dev	Filesize PR	Diff
462 kB (111.4 kB)	462 kB (111.4 kB)	+0 B

[sunag]

We could consider it to be the default if it is in a static group.