Arena 3D Viewer: True fisheye shader for fly eye simulation

[mbreiser]

Summary

Implement a true fisheye/barrel distortion shader to better simulate what a fly sees from the center of the arena.

Background

The current FOV slider adjusts the camera's perspective FOV up to 170°, but this doesn't produce the barrel distortion characteristic of wide-angle/fisheye lenses or compound eyes.

Proposed Implementation

• Add a separate "True Fly Eye" toggle or control (distinct from FOV slider)
• Implement post-processing shader with barrel distortion
• Target FOV: ~270° horizontal, ~180° vertical (matching fly compound eye coverage)
• Keep as experimental feature to evaluate usefulness

Technical Approach

Options to explore:

1. Three.js post-processing with custom fisheye shader
2. Cubemap rendering with equirectangular projection
3. Existing fisheye shader libraries

Acceptance Criteria

• Separate control for true fisheye mode
• Barrel distortion visible at edges
• Reasonable performance (may need to reduce LED count or use LOD)
• Easy to toggle on/off for comparison