Shadow Issues with CSG-Modified Meshes

Based on your description and the image provided, it appears you're experiencing an issue where shadows don't properly reflect the CSG (Constructive Solid Geometry) operations you've performed on your mesh.

Possible Causes and Solutions

When working with shadows in Three.js after CSG operations, there are a few common issues that might be occurring:

1. Shadow Map Resolution: The shadow map might not have sufficient resolution to capture the details of your CSG operation. Try increasing the shadow map size:

   JAVASCRIPTCopied
   light.shadow.mapSize.width = 2048;
   light.shadow.mapSize.height = 2048;

2. Geometry Update: After performing CSG operations, ensure that the geometry's attributes are properly updated:

   JAVASCRIPTCopied
   // After CSG operation
   resultMesh.geometry.computeBoundingSphere();
   resultMesh.geometry.computeBoundingBox();
   resultMesh.geometry.computeVertexNormals();

3. Shadow Casting Properties: Make sure the new mesh created after CSG has the correct shadow casting properties:

   JAVASCRIPTCopied
   resultMesh.castShadow = true;
   resultMesh.receiveShadow = true;

4. Light Position: The position of your light source relative to the mesh might be causing shadow artifacts. Try adjusting the light position or using a different type of light.

5. Shadow Bias: Adjusting the shadow bias might help with shadow artifacts:

   JAVASCRIPTCopied
   light.shadow.bias = -0.0001;

If you're using a specific CSG library, make sure you're following its recommended workflow for handling the resulting geometries, as some might require additional steps to ensure proper shadow rendering.

Let me know if any of these suggestions help resolve your issue or if you need more specific guidance.