Show HN: Curved Space Shader in Three.js (via 4D sphere projection)

Summary

Curved Space Shader This vertex shader was first written in HLSL for the Unity game Sfera: https://bntr.itch.io/sfera. Now it's rewritten in GLSL for three.js. Try it live: https://bntre.github.io/CurvedSpaceShader/ Demo video: https://www.youtube.com/watch?v=yhRXQAb-uh0 Math Behind the Effect To show curved space (see Spherical Geometry), each 3D model goes through a special transformation using 4D rotation and projection. For each object: The model is scaled and positioned near the center of world space. In the vertex shader: The 3D point is projected onto a 4D unit sphere (x²+y²+z²+w²=1) A 4D rotation is applied (each object has its own rotation). The point is projected back to 3D using stereographic projection. Interactive Controls Mouse Wheel: Zoom Ctrl : Rotate in ZW ("evert") : Rotate in ZW ("evert") Shift : Rotate in XY (spin) Mouse Drag: Left Button : Rotate in XZ/YZ Ctrl : Rotate in XW/YW ("evert") Shift : Scale objects in world space : Rotate in XZ/YZ Right Button : Rotate in XY (spin) : Rotate in XY (spin) Middle Button : Move the girl in world space Keyboard: Space : Pause girl animation : Pause girl animation Arrow Keys : Fly camera : Fly camera End : Stop flying : Stop flying Home : Reset scene Credits