Open-source procedural spider walks any terrain with closed-form IK, no physics engine or animation clips
majidmanzarpour · x · 2026-08-18
Developer majidmanzarpour open-sourced threejs-procedural-spider: a self-stabilizing procedural spider that walks, climbs walls and leaps across any terrain, built purely with math every frame in Three.js — no animation clips, no skeleton rig, no physics engine.
- Analytic IK legs: each leg solved per-frame with an exact two-bone closed-form inverse kinematics (hip → knee → foot), no iterative convergence.
- Improvised gait: feet are planted in world space, not on the body; when the body outruns a foot, that leg lifts and arcs to a fresh foothold, finding its own footing.
- Adaptive body: leans into slopes, walls and overhangs, with wall-latching support.
A live demo is available with sliders to drive it around. The author shared it as terrain-traversal inspiration in a reply about a Grok-generated glass-and-metal robot dog.
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