I’m trying to animate a crane lifting a box using reactor. I’m using the link constraint to get it to grab the box. I have the box linked to world till the crane hook crabs it then I link the box to the hook. It then lifts the box, rotates around and lowers the box close to the ground.  I then want it to let it fall the rest of the way, but when I link it back to the world it just sits there like it’s not being effected by gravity. The crane moves away like it’s supposed to do but box just sits there.  Is there something with reactor that needs to be done to make this happen?

D.R.
3ds Max 2011
Autodesk Inventor & AutoCAD
HP xw8600 Workstation
Windows XP Pro 64Bit
Dual Intel Xeon 2.83 E5440 GHz
8.00 GB of Ram

Did you put the objects into a Rigid Body Collection, define the properties of the objects and run the simulation starting at or after you linked the object back to the World?

If you try to run the simulation on the object that has the Link controller, the previous animation will be taken into account and not produce the desired result. (Setup A in the attached file.)

However, if you Link (on the Main toolbar) your object to a Dummy helper, and assign the Dummy the Link Constraint, then the object will behave correctly. (Setup B.)

Open the file and play the animation. The objects move the same from frame 0 to 60.
Now, go to the Utilities Panel, choose Reactor, then Create Animation. The difference is what you see in the movie.

There may be other ways to solve the problem.

Tim Wilbers [FA]

College of Arts and Sciences
Department of Visual Arts
University of Dayton
http://www.udayton.edu/
3ds Max: 7.5, 8, 9, 2008, 2009, 2010

	Attachment
reactor_with_linkconstraint.mov

	Attachment
reactor_with_linkconstraint_2009.zip

Thank you so much for responding, I was beginning to wonder if anyone was listening.
This is great, I didn’t even consider linking it to a dummy and apply the Constraint to the Dummy. But the only way I was able to get it to work was to make the Box that was linked to the Dummy Unyielding to the point of dropping, and then picking up the keys from that point making it yielding. Is this the process you did? I found if I left it yielding for the simulation the Dummy would not pick up its linked object.

D.R.
3ds Max 2011
Autodesk Inventor & AutoCAD
HP xw8600 Workstation
Windows XP Pro 64Bit
Dual Intel Xeon 2.83 E5440 GHz
8.00 GB of Ram

Not exactly.

The only two objects I have in the Rigid Body Collection are the Box to be picked up and dropped, and the Box that represents the ground. The Dummy is not part of the simulation.

Tim Wilbers [FA]

College of Arts and Sciences
Department of Visual Arts
University of Dayton
http://www.udayton.edu/
3ds Max: 7.5, 8, 9, 2008, 2009, 2010

Here’s what I am talking about. I linked the Box to the Dummy and put the Link Constraint with all the Link to World and To Object and back to World to the Dummy. Then I let Reactor Create the Keys for the Simulation. Once the Dummy got controlled by the lifting item, it doesn’t lift the Box with it. When I deleted the keys that Reactor Created, the box lifted with the dummy and then I let reactor create the keys for the spot the box drops.

My other situation is after putting a pulley on the crane arm, I want the friction of the rope to spin the pulley with the action of the rope, and I can’t get reactor to work correctly with the small tolerances in the pulley. I really look up to you guys that have spent so much time learning all of these things that people like myself rely on for help. Sometimes you just can’t get the online help you need.

D.R.
3ds Max 2011
Autodesk Inventor & AutoCAD
HP xw8600 Workstation
Windows XP Pro 64Bit
Dual Intel Xeon 2.83 E5440 GHz
8.00 GB of Ram