nice diagram lines

packages/web/src/designer/designerMath.ts

@@ -0,0 +1,92 @@
+interface IPoint {
+  x: number;
+  y: number;
+}
+
+interface IBoxBounds {
+  left: number;
+  top: number;
+  right: number;
+  bottom: number;
+}
+
+// export class Vector {
+//   constructor(public x: number, public y: number) {}
+
+//   static random() {
+//     return new Vector(10.0 * (Math.random() - 0.5), 10.0 * (Math.random() - 0.5));
+//   }
+
+//   add(v2: Vector) {
+//     return new Vector(this.x + v2.x, this.y + v2.y);
+//   }
+
+//   subtract(v2: Vector) {
+//     return new Vector(this.x - v2.x, this.y - v2.y);
+//   }
+
+//   multiply(n: number) {
+//     return new Vector(this.x * n, this.y * n);
+//   }
+
+//   divide(n: number) {
+//     return new Vector(this.x / n || 0, this.y / n || 0); // Avoid divide by zero errors..
+//   }
+
+//   magnitude() {
+//     return Math.sqrt(this.x * this.x + this.y * this.y);
+//   }
+
+//   normal(n: number) {
+//     return new Vector(-this.y, this.x);
+//   }
+
+//   normalise() {
+//     return this.divide(this.magnitude());
+//   }
+// }
+
+// helpers for figuring out where to draw arrows
+export function intersectLineLine(p1: IPoint, p2: IPoint, p3: IPoint, p4: IPoint): IPoint {
+  var denom = (p4.y - p3.y) * (p2.x - p1.x) - (p4.x - p3.x) * (p2.y - p1.y);
+
+  // lines are parallel
+  if (denom === 0) {
+    return null;
+  }
+
+  var ua = ((p4.x - p3.x) * (p1.y - p3.y) - (p4.y - p3.y) * (p1.x - p3.x)) / denom;
+  var ub = ((p2.x - p1.x) * (p1.y - p3.y) - (p2.y - p1.y) * (p1.x - p3.x)) / denom;
+
+  if (ua < 0 || ua > 1 || ub < 0 || ub > 1) {
+    return null;
+  }
+
+  return {
+    x: p1.x + ua * (p2.x - p1.x),
+    y: p1.y + ua * (p2.y - p1.y),
+  };
+}
+
+export function intersectLineBox(p1: IPoint, p2: IPoint, box: IBoxBounds): IPoint {
+  var tl = { x: box.left, y: box.top };
+  var tr = { x: box.right, y: box.top };
+  var bl = { x: box.left, y: box.bottom };
+  var br = { x: box.right, y: box.bottom };
+
+  var result;
+  if ((result = intersectLineLine(p1, p2, tl, tr))) {
+    return result;
+  } // top
+  if ((result = intersectLineLine(p1, p2, tr, br))) {
+    return result;
+  } // right
+  if ((result = intersectLineLine(p1, p2, br, bl))) {
+    return result;
+  } // bottom
+  if ((result = intersectLineLine(p1, p2, bl, tl))) {
+    return result;
+  } // left
+
+  return null;
+}