feat(vectors): migrate direction(), normalLeft/Right2() from geom pkg

thi-ng · Jan 21, 2019 · 07d5f8f · 07d5f8f
1 parent 862ed08
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diff --git a/packages/vectors/README.md b/packages/vectors/README.md
@@ -303,8 +303,10 @@ Functions for memory mapped, strided vectors (without requiring wrappers):
 - `angleBetween2` / `angleBetween3`
 - `angleRatio`
 - `bisect2`
+- `direction`
 - `faceForward`
 - `heading` / `headingXY` / `headingXZ` / `headingYZ`
+- `normalLeft2` / `normalRight2`
 - `perpendicularLeft2` / `perpendicularRight2`
 - `project`
 - `reflect`

diff --git a/packages/vectors/src/direction.ts b/packages/vectors/src/direction.ts
@@ -0,0 +1,15 @@
+import { ReadonlyVec, Vec } from "./api";
+import { normalize } from "./normalize";
+import { sub } from "./sub";
+
+/**
+ * Computes direction vector `a` -> `b`, normalized to length `n`
+ * (default 1).
+ *
+ * @param a
+ * @param b
+ * @param n
+ */
+export const direction =
+    (out: Vec, a: ReadonlyVec, b: ReadonlyVec, n = 1) =>
+        normalize(null, sub(out || a, b, a), n);
diff --git a/packages/vectors/src/index.ts b/packages/vectors/src/index.ts
@@ -30,6 +30,7 @@ export * from "./copy";
 export * from "./cos";
 export * from "./cosh";
 export * from "./cross";
+export * from "./direction";
 export * from "./dist";
 export * from "./dist-chebyshev";
 export * from "./dist-manhattan";
@@ -74,6 +75,7 @@ export * from "./mul";
 export * from "./muln";
 export * from "./muls";
 export * from "./neg";
+export * from "./normal";
 export * from "./normalize";
 export * from "./ortho-normal";
 export * from "./perpendicular";

diff --git a/packages/vectors/src/normal.ts b/packages/vectors/src/normal.ts
@@ -0,0 +1,31 @@
+import { ReadonlyVec, Vec } from "./api";
+import { direction } from "./direction";
+import { perpendicularLeft2, perpendicularRight2 } from "./perpendicular";
+
+/**
+ * Computes 2D normal by rotating direction vector `a` -> `b`, 90 deg
+ * counterclockwise, normalized to length `n` (default: 1). If `out` is
+ * null, creates new vector.
+ *
+ * @param out
+ * @param a
+ * @param b
+ * @param n
+ */
+export const normalLeft2 =
+    (out: Vec, a: ReadonlyVec, b: ReadonlyVec, n = 1) =>
+        perpendicularLeft2(null, direction(out || [], a, b, n));
+
+/**
+ * Computes 2D normal by rotating direction vector `a` -> `b`, 90 deg
+ * clockwise, normalized to length `n` (default: 1). If `out` is null,
+ * creates new vector.
+ *
+ * @param out
+ * @param a
+ * @param b
+ * @param n
+ */
+export const normalRight2 =
+    (out: Vec, a: ReadonlyVec, b: ReadonlyVec, n = 1) =>
+        perpendicularRight2(null, direction(out || [], a, b, n));