WebGPU MRT Demo Error with forceWebGL

Based on the information provided, you're encountering an error when trying to use the forceWebGL option with the WebGPU MRT (Multiple Render Targets) demo.

The Issue

The error occurs because the WebGPU MRT demo is specifically designed to use WebGPU features that aren't directly compatible with WebGL. When you set forceWebGL: true, you're attempting to force the WebGPU renderer to use WebGL instead, but the demo code is likely using WebGPU-specific features that don't have direct WebGL equivalents.

Possible Solutions

1. Remove the forceWebGL option:

   JAVASCRIPTCopied
   renderer = new THREE.WebGPURenderer({
       antialias: true
       // Remove forceWebGL: true
   });

2. Use WebGLRenderer directly if you need to use WebGL:

   JAVASCRIPTCopied
   renderer = new THREE.WebGLRenderer({
       antialias: true
   });

3. Modify the demo code to be compatible with both WebGPU and WebGL. This would require significant changes to handle the differences between the two APIs, especially for MRT implementations.

Why This Happens

The MRT (Multiple Render Targets) implementation in WebGPU has different capabilities and syntax compared to WebGL. The demo is likely using WebGPU-specific features for setting up render targets, shaders, and pipelines that don't translate directly to WebGL when the forceWebGL flag is enabled.

If you need to use WebGL specifically, you might need to look for a WebGL-specific MRT example or adapt the current example to work with WebGL's approach to multiple render targets.