Material Lighting Differences in Three.js

The difference in lighting behavior you're observing between MeshStandardMaterial and MeshToonMaterial is due to the fundamentally different lighting models these materials use.

MeshStandardMaterial

MeshStandardMaterial is a physically-based material that uses the Metallic-Roughness workflow. It's designed to interact with light in a physically accurate way, which means:

• It responds to all types of lights in your scene
• It shows subtle gradations in lighting and shadows
• It can reflect environment lighting realistically
• It processes light per-fragment for more accurate results

As the documentation states, this material provides "more precise and realistic results" compared to simpler materials, though at a higher computational cost.

MeshToonMaterial

MeshToonMaterial is specifically designed for cartoon-like, cel-shaded rendering. It:

• Uses a simplified lighting model
• Creates more defined, sharp transitions between light and shadow
• Doesn't respond to lighting in the same nuanced way as physically-based materials
• May not interact with certain light types in the same way

Why the Difference

The ceiling light in your scene is likely affecting both materials, but:

1. With MeshStandardMaterial, you see subtle light gradients and reflections because it's designed to accurately model light physics
2. With MeshToonMaterial, you see more defined shadows but less subtle lighting effects because it's designed for stylized rendering with sharp transitions

Getting Your Desired Effect

If you want the cartoon-like appearance of MeshToonMaterial but with better response to your ceiling light, you could:

1. Increase the intensity of your ceiling light
2. Adjust the gradientMap property of your MeshToonMaterial to allow for more lighting steps
3. Consider using MeshPhongMaterial with a low shininess value as a middle ground

Alternatively, if you prefer the lighting of MeshStandardMaterial but want more defined shadows, you could adjust its roughness and metalness properties to get a more stylized look while maintaining its superior light handling.