WebGPU Sample Count Mismatch Error

The error you're encountering is related to a mismatch in sample counts between textures in WebGPU. Specifically, the error indicates that you're trying to copy between textures with different sample counts (4 vs 1), which isn't allowed in WebGPU.

Understanding the Issue

The error occurs when:

• A source texture has a sample count of 4 (multisampled)
• A destination texture has a sample count of 1 (no multisampling)
• You're attempting to copy between these textures with different sample counts

This is happening with both the waterMaterial.backdropNode and lensflareMesh components.

Potential Solutions

Since you're using Three.js version 171 with the WebGPU renderer and specifically the backdrop_water example, here are some approaches to resolve this:

1. Match the sample counts: Ensure both textures have the same sample count. You can do this by:

   JAVASCRIPTCopied
   // When creating your renderer
   const renderer = new THREE.WebGPURenderer({
     antialias: true,
     sampleCount: 1 // Set this to match your destination texture
   });

2. Use a resolve step: Instead of directly copying between multisampled and non-multisampled textures, you might need to resolve the multisampled texture first:

   JAVASCRIPTCopied
   // If you have control over the render process
   renderer.setPixelRatio(window.devicePixelRatio);
   renderer.setSize(window.innerWidth, window.innerHeight);
   // Make sure any post-processing or custom render targets use matching sample counts

3. Check your render targets: If you're creating custom render targets for the water effect:

   JAVASCRIPTCopied
   const renderTarget = new THREE.WebGPURenderTarget(width, height, {
     sampleCount: 1, // Match this with your renderer's sample count
     // other parameters...
   });

4. Update Three.js: If possible, check if there's a newer version or patch available that addresses this specific WebGPU issue.

The backdrop_water example uses advanced rendering techniques with the node material system, and these WebGPU-specific errors can occur when there's a mismatch in how textures are configured for multisampling.