feat(geom-poly-utils): move barycentric fns from main geom pkg

thi-ng · Jan 25, 2019 · 68a26f4 · 68a26f4
1 parent 74aa954
commit 68a26f4
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diff --git a/packages/geom-poly-utils/src/barycentric.ts b/packages/geom-poly-utils/src/barycentric.ts
@@ -0,0 +1,29 @@
+import {
+    addW3,
+    dot,
+    magSq,
+    ReadonlyVec,
+    setC3,
+    sub,
+    Vec
+} from "@thi.ng/vectors";
+
+export const toBarycentric =
+    (a: ReadonlyVec, b: ReadonlyVec, c: ReadonlyVec, p: ReadonlyVec, out: Vec = []) => {
+        const u = sub([], b, a);
+        const v = sub([], c, a);
+        const w = sub([], p, a);
+        const uu = magSq(u);
+        const vv = magSq(v);
+        const uv = dot(u, v);
+        const uw = dot(u, w);
+        const vw = dot(v, w);
+        const d = 1 / (uv * uv - uu * vv);
+        const s = d * (uv * vw - vv * uw);
+        const t = d * (uv * uw - uu * vw);
+        return setC3(out, 1 - (s + t), s, t);
+    };
+
+export const fromBarycentric =
+    (a: ReadonlyVec, b: ReadonlyVec, c: ReadonlyVec, p: ReadonlyVec, out?: Vec) =>
+        addW3(out, a, b, c, p[0], p[1], p[2]);
diff --git a/packages/geom-poly-utils/src/index.ts b/packages/geom-poly-utils/src/index.ts
@@ -1,4 +1,5 @@
 export * from "./area";
+export * from "./barycentric";
 export * from "./bounds";
 export * from "./center-of-weight";
 export * from "./centroid";