feat(geom-isec): add intersectLinePolylineAll()

packages/geom-isec/src/index.ts

@@ -2,6 +2,7 @@ export * from "./point";
 
 export * from "./circle-circle";
 export * from "./line-line";
+export * from "./line-poly";
 export * from "./plane-plane";
 export * from "./ray-circle";
 export * from "./ray-line";

packages/geom-isec/src/line-poly.ts

@@ -0,0 +1,37 @@
+import { IntersectionResult, IntersectionType } from "@thi.ng/geom-api";
+import { maddN2, mag, normalize, ReadonlyVec, sub, Vec } from "@thi.ng/vectors";
+import { NONE } from "./api";
+import { intersectRayLine } from "./ray-line";
+
+export const intersectLinePolylineAll = (
+    a: ReadonlyVec,
+    b: ReadonlyVec,
+    pts: ReadonlyVec[],
+    closed = false
+): IntersectionResult => {
+    const dir = sub([], b, a);
+    const maxD = mag(dir);
+    normalize(null, dir);
+    const n = pts.length - 1;
+    let i, j;
+    if (closed) {
+        i = pts[n];
+        j = pts[0];
+    } else {
+        i = pts[0];
+        j = pts[1];
+    }
+    const res: [number, Vec][] = [];
+    for (let k = 0; k <= n; i = j, j = pts[++k]) {
+        const d = intersectRayLine(a, dir, i, j).alpha;
+        if (d !== undefined && d >= 0 && d <= maxD) {
+            res.push([d, maddN2([], dir, d, a)]);
+        }
+    }
+    return res.length
+        ? {
+              type: IntersectionType.INTERSECT,
+              isec: res.sort((a, b) => a[0] - b[0]).map((x) => x[1]),
+          }
+        : NONE;
+};