;Check if two bounding boxes intersect
;  input
;    bbox1 - 4 element array of ints, [left, bottom, right, top] describing a bbox
;    bbox2 - 4 element array of ints, describing the other bbox
;  return
;    1 if bboxes intersect, 0 otherwise
;
function is_bbox_intersect,bbox1,bbox2
  if bbox1[2] lt bbox2[0] then return,0 ;if bbox1.right<bbox2.left, no intersect
  if bbox1[0] gt bbox2[2] then return,0 ;if bbox1.left>bbox2.right, no intersect
  if bbox1[3] lt bbox2[1] then return,0 ;if bbox1.top<bbox2.bottom, no intersect
  if bbox1[1] gt bbox2[3] then return,0 ;if bbox1.bottom>bbox2.top, no intersect
  return,1
end