spline_positions_to_curve

# function that takes array of Vector3, returns a spline between them (as a Curve3D)

static func spline_positions_to_curve(marker_positions: Array, curve_strength: float) -> Curve3D:
    
    var curve3D: Curve3D = Curve3D.new()

    for i in marker_positions.size():
        
        var pos = marker_positions[i] # curve pos
        var _in: Vector3 = Vector3() # the in and out directions (opposite for unbroken curve)
        var _out: Vector3 = Vector3()

        if i > 0 and i < marker_positions.size() - 1:
            
            var posA1: Vector3 = marker_positions[i-1]
            var posA2: Vector3 = marker_positions[i+1]
            
            var offset1: Vector3 = posA1 - pos
            var offset2: Vector3 = posA2 - pos
            
            offset1 = offset1.normalized()
            offset2 = offset2.normalized()
            
            var offset3: Vector3 = offset1
            
            offset3 -= offset2 # we add minus as it's opposite direction
            offset3 = offset3.normalized()
            
            offset3 *= curve_strength

            _in = offset3
            _out = -offset3
            
        curve3D.add_point(pos, _in, _out)

    return curve3D