bbox distance

bbox_distance.js

class BBox {
   constructor(bbox) {
       let x = bbox[0];
       let y = bbox[1];
       this.width = bbox[2];
       this.height = bbox[3];
       this.midX = x + this.width / 2;
       this.midY = y + this.height / 2;
   }
 
   distance(bbox) {
       let xDiff = Math.abs(this.midX - bbox.midX) - this.width / 2 - bbox.width / 2;
       let yDiff = Math.abs(this.midY - bbox.midY) - this.height / 2 - bbox.height / 2;
 
       // If xDiff < 0, the boxes intersect in the x plane. Thus the distance is just the
       // y height, or 0 if the boxes intersect in the y plane, too.
       if(xDiff < 0) {
           return Math.max(yDiff, 0);
       }
       // In this case, boxes intersect in y plane but not x plane.
       if(yDiff < 0) {
           return xDiff;
       }
       // BBoxes intersect in neither plane. Return the Euclidean distance between
       // the closest corners.
       return Math.sqrt(xDiff**2 + yDiff**2);
   }
 }
 
 
 function checkIfNear(item1, item2, distance=0) {
   const BOUNDING_BOX_1 = new BBox(item1.bbox);
   const BOUNDING_BOX_2 = new BBox(item2.bbox);
   return BOUNDING_BOX_1.distance(BOUNDING_BOX_2) <= distance;
 }