wip-计算折线平行线

src/jlgraphic/utils/GraphicUtils.ts

@@ -2,6 +2,7 @@ import {
   Container,
   DisplayObject,
   IPointData,
+  Matrix,
   Point,
   Rectangle,
 } from 'pixi.js';
@@ -693,3 +694,37 @@ export function splitLineEvenly(
       ];
     });
 }
+
+/** 计算折线的平行线 */
+export function getParallelOfPolyline(
+  points: IPointData[],
+  direction: 'L' | 'R',
+  offset: number
+) {
+  if (points.length < 2) throw Error('折线点不能少于2个');
+  const normalVecs = points.map((p, i) => {
+    if (points[i - 1] && points[i + 1]) {
+    } else {
+      let point;
+      if (points[i + 1]) {
+        point = new Vector2([
+          points[i + 1].x - p.x,
+          points[i + 1].y - p.y,
+        ]).normalize();
+      } else {
+        point = new Vector2([
+          p.x - points[i - 1].x,
+          p.y - points[i - 1].y,
+        ]).normalize();
+      }
+      const rotate = new Matrix().rotate(
+        (direction === 'L' ? Math.PI : -Math.PI) / 2
+      );
+      return rotate.apply(point);
+    }
+  });
+  return points.map((p, i) => ({
+    x: p.x + offset * normalVecs[i]?.x,
+    y: p.y + offset * normalVecs[i]?.y,
+  }));
+}