   Rod / Stick dynamics
  Hi AllI am trying to achieve something which has had me scratching my head for quite a few days now - I hope I can explain it well enough!My end goal is to have a rod/stick which is pivoted at one of its ends with the ability to move it around using the opposite end to the pivot.The idea is that you could grab hold of one end of the rod and use it to control the position of its opposite end in a push me / pull me / follow me type motion.To clarify furter if for example the rod was in the following position&nbsp&nbsp&nbsp&nbsp&nbspx&nbsp&nbsp&nbsp&nbsp&nbsp|&nbsp&nbsp&nbsp&nbsp&nbsp|&nbsp&nbsp&nbsp&nbsp&nbsp|&nbsp&nbsp&nbsp&nbsp&nbsp|&nbsp&nbsp&nbsp&nbsp&nbspoand you were then to grab its bottom (o) and pull it along only the x axis you would eventually end up with the rod in the following position&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbspx--------oI hope this makes sense?!It has been a while since I did my A level maths and thing are a bit rusty. If anyone could give me pointers in the direction I should start to focus my reserch and/or any advice on how to solve my problem it would be much appreciated!ThanksZak.   
  You could anchor one end of the rod (call it X) while the other end can move (call it O), then you move end O by the amount you wish (drag by a mouse, pull by anything,..), then you should check the constraint of the rod, ie, if the distance between X and O is greater than or smaller than the rod's length, then move end O by a distance of -delta (where delta is the extension/compression that occured).I would recommend you to have a look at this. It discusses a similar subject.   ;  Thanks AHashem This information will definetly prove useful.Just to clarify would a method simliar to your suggestion take into account any rotation or would another method have to be considered for this?e.g. if dragging point ( o ) along the line below would Diagram A or Diagram B be true?-------------DIAGRAM A-----------------   x x x  |  \  \   x |   \   \    \    x  __    |    \    \\   __   ___o__________o__________o___________o______________o_____x--------o____. ---- direction of travel ----->.point ( x ) is gradually dragged until it is inline with the direction of travel -------------DIAGRAM B-----------------   x x x x x | | | | | | | | | | | | | | |   ___o______o______o______o______o___  . ---- direction of travel ----->.point ( x ) remains in at the same location and is simply translated in the x,y relative to point ( o ).Thanks again.Zak.   ;  If I understand you correctly, then diagram A should be the true one.If you drag point X to the right without satisfying the rod-constraint, then it should look like this:O|.|..|__X______But the rod now is over-extended, so by satisfying the constraint, you would push X towards O by an amount, which should look like this:O|.|..X___________Note that the Y-value of the point X is affected when satisfying the constraint, so after a few iterations of dragging X and resolving the constraint it, yea, should reach to a horizontal line.HTH,Atef   ;  WOW!I just knocked together a bit of code as a rough test and it brilliant! It works exactly how I imagined.I cant believe how much I was over complicating the issue, you should have seen some of the things I was trying before you stepped in!!Next step is to add some collision detection to opposite end of the rod to which I am pulling / pushing!Thanks for all your help Atef you have saved me hours of going nowhere!Zak.   