# 2. Knots and Tangent Modes Part of [[Splines]]. Prev: [[1. Install and SplineContainer]]. Next: [[3. Evaluate and Placement]]. ## 2.1 Knots A **knot** is a point on the spline plus tangent data. Add, move, and delete knots with the Spline tool in the Scene view (package documentation lists the current shortcuts - do not memorize a forum post). Keep knot counts modest: a 200-knot fence is a placement job (part 3), not a sculpt. ## 2.2 Tangent modes Unity Splines knots support tangent modes in the family of **Auto**, **Linear** / broken, **Mirrored**, and **Continuous** (exact enum / Inspector names: confirm in 2.9.2 `TangentMode` and the edit overlay). Practical use: - **Auto / continuous**: roads and camera dollies - no kink at the knot. - **Linear**: a sharp corner (a platform that should not round a shelf). - **Broken / mirrored**: hand-tuned ease into a landing. Do not leave a dolly on a linear polyline unless the camera *should* jerk. ## 2.3 Open vs closed A **closed** spline loops; `SplineAnimate` can loop around it. A patrol that must return to start should be closed, or an open spline with loop mode that ping-pongs (part 4). Confirm the Inspector checkbox / `Closed` property on the `Spline` in 2.9.2. ## 2.4 Up vector and roll `SplineUtility.Evaluate` gives an `upVector` as well as a tangent. Twisted up-vectors show up as rolling cameras and leaning props. Keep the spline reasonably planar unless you *want* a corkscrew, and preview a test cube's orientation before you attach a camera. ## 2.5 Exercise Build a closed four-knot loop around a gray-box courtyard ([[ProBuilder Gray-Boxing and Landmarks]]). Give three corners Auto tangents and one Linear corner. You will walk a cube around it in part 4. ## Sources - Splines package manual (2.9; use the package ToC for "Edit a spline" / tangent mode pages): https://docs.unity3d.com/Packages/[email protected]/manual/index.html