A web-based 3D simulation system that recreates the experience of haptic (touch-based) interaction with virtual objects. Originally developed in 2008 at Universidad de Concepcion using C++/CLI, OpenGL, and a physical PHANToM Omni haptic device, the modern version replaces hardware dependencies with browser-based mouse and slider interaction while preserving the core physics engine.

Collision detection

Spatial queries use an octree partitioning structure (max depth of 4) that reduces broad-phase collision detection to O(n log n). For narrow-phase resolution, the system applies the Separating Axis Theorem (SAT) for exact triangle-triangle intersection testing across 11 potential separating axes (3 face normals per triangle plus 5 edge cross-products from the non-parallel edge pairs). This two-phase approach keeps the simulation responsive even with moderately complex meshes.

Force feedback model

Contact forces follow a spring-damper model based on Hooke’s law with viscous damping — a Kelvin-Voigt formulation: F = -kd - bv, where k is the spring stiffness, d is the penetration depth, b is the damping coefficient, and v is the relative velocity at the contact point. The model produces stable, physically plausible resistance when the user’s proxy intersects a surface. Wavefront OBJ mesh loading with fan triangulation handles arbitrary geometry, and Three.js with WebGL provides the rendering layer.

Origin and context

This was my 2008 undergraduate thesis project at Universidad de Concepcion, part of a FONDEF-funded project aimed at building arthroscopic surgical training simulators. The haptic device work was also the technology exploration that directly led to the FeelIT project — a haptic interface for visually impaired people. The legacy C++/CLI code is preserved alongside the modern Python/FastAPI web application.