Integrating HDR Lighting with Traditional Lights in Three.js

Based on the available information about Three.js lighting, I can provide some guidance on your questions:

Combining HDR with Traditional Lights

When using HDR images for lighting (typically through environment maps or LightProbe), you may still want to add traditional lights depending on your specific needs:

• HDR environment maps provide realistic ambient lighting and reflections
• Traditional lights like DirectionalLight or SpotLight are still useful for:
  • Creating specific highlights
  • Generating shadows (which HDR lighting alone doesn't provide)
  • Adding emphasis to certain areas of your scene

Creating Shadows with HDR Lighting

For floor shadows when using HDR lighting:

• Yes, you'll need to add additional light sources like DirectionalLight or SpotLight as HDR environment lighting doesn't cast shadows by itself
• To align these lights with your HDR background:
  • Analyze the brightest areas in your HDR image
  • Position your DirectionalLight to match the apparent direction of the main light source in the HDR
  • Adjust intensity to complement rather than overpower the HDR lighting

Environment Rotation

Regarding environment rotation, the documentation doesn't specifically address how applications like Sketchfab achieve this effect. This might involve custom implementations or extensions beyond what's covered in the standard Three.js documentation.

For your specific lighting needs, you might want to explore combinations of:

• AmbientLight for general fill lighting
• DirectionalLight for main shadows
• PointLight for localized effects
• HemisphereLight for sky/ground ambient lighting

Each of these can be fine-tuned to work harmoniously with your HDR environment.