feat(geom-resample): add sampleUniformX/Y() fns

- update deps (add thi.ng/geom-isec)
- update pkg

packages/geom-resample/package.json

@@ -37,6 +37,7 @@
 		"@thi.ng/checks": "^3.3.6",
 		"@thi.ng/geom-api": "^3.3.24",
 		"@thi.ng/geom-closest-point": "^2.1.38",
+		"@thi.ng/geom-isec": "^2.1.41",
 		"@thi.ng/math": "^5.3.18",
 		"@thi.ng/vectors": "^7.5.30"
 	},
@@ -80,6 +81,9 @@
 		".": {
 			"default": "./index.js"
 		},
+		"./axis": {
+			"default": "./axis.js"
+		},
 		"./resample": {
 			"default": "./resample.js"
 		},

packages/geom-resample/src/axis.ts

@@ -0,0 +1,79 @@
+import { intersectRayPolyline } from "@thi.ng/geom-isec/ray-poly";
+import type { ReadonlyVec } from "@thi.ng/vectors";
+
+/**
+ * Samples 2D polyline at uniform step distance in `[x1..x2]` interval along
+ * X-axis. Returns array of sampled points.
+ *
+ * @remarks
+ * The polyline is assumed to fully cover the given X interval, no gaps are
+ * allowed (or checked for). Sampling is done via ray-line intersection with the
+ * ray cast into Y+ direction, starting at given `startY`.
+ *
+ * Also see {@link sampleUniformY}.
+ *
+ * @example
+ * ```ts
+ * sampleUniformX([[0, 0], [3, 5], [5, 2]], 0, 5)
+ * // [
+ * //   [ 0, 0 ],
+ * //   [ 1, 1.666... ],
+ * //   [ 2, 3.333... ],
+ * //   [ 3, 5 ],
+ * //   [ 4, 3.5 ],
+ * //   [ 5, 2 ]
+ * // ]
+ * ```
+ *
+ * @param pts
+ * @param x1
+ * @param x2
+ * @param step
+ * @param startY
+ */
+export const sampleUniformX = (
+	pts: ReadonlyVec[],
+	x1: number,
+	x2: number,
+	step = 1,
+	startY = -1
+) => {
+	const res: ReadonlyVec[] = [];
+	for (let x = x1; x <= x2; x += step) {
+		res.push(
+			<ReadonlyVec>(
+				intersectRayPolyline([x, startY], [0, 1], pts, false).isec!
+			)
+		);
+	}
+	return res;
+};
+
+/**
+ * Similar to {@link sampleUniformX}, but samples 2D polyline at uniform step
+ * distance in `[y1..y2]` interval along Y-axis. Returns array of sampled
+ * points.
+ *
+ * @param pts
+ * @param y1
+ * @param y2
+ * @param step
+ * @param startX
+ */
+export const sampleUniformY = (
+	pts: ReadonlyVec[],
+	y1: number,
+	y2: number,
+	step = 1,
+	startX = -1
+) => {
+	const res: ReadonlyVec[] = [];
+	for (let y = y1; y <= y2; y += step) {
+		res.push(
+			<ReadonlyVec>(
+				intersectRayPolyline([startX, y], [1, 0], pts, false).isec!
+			)
+		);
+	}
+	return res;
+};

packages/geom-resample/src/index.ts

@@ -1,3 +1,4 @@
+export * from "./axis.js";
 export * from "./resample.js";
 export * from "./sampler.js";
 export * from "./simplify.js";

yarn.lock

@@ -3369,6 +3369,7 @@ __metadata:
     "@thi.ng/checks": ^3.3.6
     "@thi.ng/geom-api": ^3.3.24
     "@thi.ng/geom-closest-point": ^2.1.38
+    "@thi.ng/geom-isec": ^2.1.41
     "@thi.ng/math": ^5.3.18
     "@thi.ng/testament": ^0.3.8
     "@thi.ng/vectors": ^7.5.30