ThreeJS Shadow Map Issue with R3F AccumulativeShadows

Based on the information provided, you're experiencing an issue with the AccumulativeShadows component from React Three Fiber's drei library when using ThreeJS versions 155 and above. The shadow map appears to be completely darkened rather than showing the expected subtle shadows with a mostly transparent background.

Potential Solutions

This appears to be related to changes in how shadow maps are handled in newer versions of ThreeJS. Here are some potential approaches to resolve the issue:

1. Check Shadow Map Configuration:
   The WebGLRenderer.shadowMap property has several settings that might need adjustment:

   JAVASCRIPTCopied
   // In your renderer setup
   renderer.shadowMap.enabled = true;
   renderer.shadowMap.type = THREE.PCFSoftShadowMap; // Try different shadow map types

2. Adjust AccumulativeShadows Parameters:
   Try modifying the opacity, scale, or other parameters of the AccumulativeShadows component:

   JSXCopied
   <AccumulativeShadows
     temporal
     frames={100}
     color="black"
     colorBlend={0.5}
     opacity={0.8} // Try reducing this value
     scale={10}
     // Add other parameters as needed
   />

3. Try Different Shadow Types:
   ThreeJS offers several shadow types that might work better with newer versions:

   • THREE.BasicShadowMap
   • THREE.PCFShadowMap (default)
   • THREE.PCFSoftShadowMap
   • THREE.VSMShadowMap

4. Check for Breaking Changes:
   Since this issue appears in ThreeJS versions >=155, there might be breaking changes in the shadow implementation that require updates to the AccumulativeShadows component.

5. File an Issue:
   This might be a bug in the drei library when used with newer ThreeJS versions. Consider filing an issue on the drei GitHub repository with your reproduction case.

Since you're using the RC versions of R3F and drei with React 19, there could be compatibility issues that haven't been fully resolved yet. You might need to wait for stable releases that properly support the newer ThreeJS versions.