WebGPURenderer: WebGL2 backend: moving directional light causes shadow flickering

[srfall]

Description

I am using a DirectionalLight and update its position when the camera has moved. This works fine with the WebGlRenderer, but I try the same thing with the WebGPURenderer (in Firefox), every time the light is moved, the shadows glitch. I would expect the same behavior in the WebGL2 fallback as when directly using the WebGlRenderer.

Reproduction steps

1. Copy / open the two shadowmap examples for WebGl and WebGPU
2. Insert e.g:

scene.add(dirLight.target);
const cameraLightOffset = new THREE.Vector3().copy(camera.position).sub(dirLight.position);
controls.addEventListener('change', () => {
    dirLight.position.copy(camera.position).sub(cameraLightOffset);
    dirLight.target.position.copy(controls.target);
});

or any other code that updates the dirLight position when the camera position changes.

3. Notice that the shadows look fine in the webGL version, but in the WebGPU->WebGL2 fallback version, they glitch

Code

// see live example

Live example

• jsfiddle-latest-release WebGLRenderer: looks ok

• jsfiddle-latest-release WebGPURenderer: glitch when moving

Screenshots

No response

Version

r171

Device

Desktop

Browser

Firefox

OS

Windows

[sunag]

I was fixed in dev branch #30064