everything

common/Geometry.js

@@ -0,0 +1,50 @@
+function pointSub(a, b) {
+  return { x: a.x - b.x, y: a.y - b.y }
+}
+
+function pointAdd(a, b) {
+  return { x: a.x + b.x, y: a.y + b.y }
+}
+
+function pointDistance(a, b) {
+  const diffX = a.x - b.x
+  const diffY = a.y - b.y
+  return Math.sqrt(diffX * diffX + diffY * diffY)
+}
+
+function pointInBounds(pt, rect) {
+  return pt.x >= rect.x
+    && pt.x <= rect.x + rect.w
+    && pt.y >= rect.y
+    && pt.y <= rect.y + rect.h
+}
+
+function rectCenter(rect) {
+  return {
+    x: rect.x + (rect.w / 2),
+    y: rect.y + (rect.h / 2),
+  }
+}
+
+function rectMoved(rect, x, y) {
+  return {
+    x: rect.x + x,
+    y: rect.y + y,
+    w: rect.w,
+    h: rect.h,
+  }
+}
+
+function rectCenterDistance(rectA, rectB) {
+  return pointDistance(rectCenter(rectA), rectCenter(rectB))
+}
+
+export default {
+  pointSub,
+  pointAdd,
+  pointDistance,
+  pointInBounds,
+  rectCenter,
+  rectMoved,
+  rectCenterDistance,
+}