Function isEdgeActive

isEdgeActive(
    normal1: Vec3,
    normal2: Vec3,
    edgeDirection: Vec3,
    cosThresholdAngle: number,
): boolean
Determine if an edge between two triangles should be treated as collidable.

An active edge is one that either:
- Has no neighboring triangle (mesh boundary)
- Forms a sharp convex crease (angle > threshold)
Inactive edges occur at:
- Nearly coplanar triangle junctions (smooth surfaces)
- Concave creases (always inactive to prevent snagging)
Parameters
- normal1: Vec3
  normal of left triangle (looking along edge from above)
- normal2: Vec3
  normal of right triangle
- edgeDirection: Vec3
  vector pointing along the edge
- cosThresholdAngle: number
  cosine of threshold angle (typically cos(10°) ≈ 0.9848)
Returns boolean
true if edge should generate collisions, false if inactive
- Defined in src/collision/active-edges.ts:40