添加工具方法

src/jlgraphic/utils/GraphicUtils.ts

@@ -542,3 +542,68 @@ export function angleOfIncludedAngle(
   }
   return angle;
 }
+
+/**
+ * 计算两点连线的法向量
+ * @param point1
+ * @param point2
+ * @returns 单位法向量
+ */
+export function getNormalVector(
+  point1: IPointData,
+  point2: IPointData
+): number[] {
+  const x1 = point1.x,
+    y1 = point1.y;
+  const x2 = point2.x,
+    y2 = point2.y;
+  const length = Math.sqrt((y2 - y1) ** 2 + (x2 - x1) ** 2);
+  return [(y2 - y1) / length, (x1 - x2) / length];
+}
+
+/**
+ * 点延向量方向移动
+ * @param point
+ * @param normal  单位向量
+ * @param length 平移长度
+ * @returns 移动后的点
+ */
+export function movePointAlongNormal(
+  point: IPointData,
+  normal: number[],
+  length: number
+): Point {
+  const newPoint = new Point(
+    point.x + length * normal[0],
+    point.y + length * normal[1]
+  );
+  return newPoint;
+}
+
+/**
+ * 计算两组点各自组成直线的相交点(若两线平行 返回第一组坐标第一个点)
+ * @param line1 两点坐标列表
+ * @param line2 两点坐标列表
+ * @returns 相交点
+ */
+export function getIntersectionPoint(line1: number[], line2: number[]) {
+  const a1 = line1[0],
+    b1 = line1[1];
+  const a2 = line1[2],
+    b2 = line1[3];
+  const a3 = line2[0],
+    b3 = line2[1];
+  const a4 = line2[2],
+    b4 = line2[3];
+  const denominator = (a3 - a4) * (b1 - b2) - (a1 - a2) * (b3 - b4);
+  if (denominator === 0) {
+    return new Point(a1, b1);
+  }
+  const x =
+    ((a3 - a4) * (a2 * b1 - a1 * b2) - (a1 - a2) * (a4 * b3 - a3 * b4)) /
+    denominator;
+  const y =
+    ((b3 - b4) * (b2 * a1 - b1 * a2) - (b1 - b2) * (b4 * a3 - b3 * a4)) /
+    -denominator;
+  return new Point(x, y);
+}