Turning OFF force rotation then triggering it ON. | Forums

[rlmergeuser]

I cannot for the life of me figure out how to do this.

Lets say I have a very very simple force rotation object. An I beam connected to a piece of wood. The Physics are ON for the I beam and the physics are OFF for the wood.

The I beam then rotates. Awesome!


Now here is the problem. I don't want the I beam to rotate until I trigger it to do so.

There are two ways of doing this.

1) Turn the physics of the I beam OFF, then trigger it ON. This is undesirable because the force rotation hinge is still ON, and when it's on, it is creating this built up force on the I beam, so when the I beam physics is finally triggered, it goes wonky all over the place while it tries to catch up with the hinge.

2) Turn the physics of the Force Rotation OFF, then trigger it ON. This would be EXACTLY how I want to do it, but the problem I am having is that after the Force Rotation Physics is triggered ON, the hinge simply un-glues from the objects and falls to the ground.

I've never had issues like this before, I've built some pretty complex physics objects and I can't help but think that I am either doing something fundamentally wrong, or you simply cannot trigger a Force Rotation this way.


Also, since we are on the topic of the Force Rotation hinges...

Is there any way of knowing which side of the hinge spins, and in which direction, other than just gluing it and finding out the hard way?

I would appreciate help in this regard.

[jonofthejungle9]

What about leaving the physics on, so it would rotate, and putting a plank of wood or something to stop it until it's triggered?

[jonofthejungle9]

Sorry for double post, but for the force rotation hinge always starts in the same position, so create a simple 1 and work out how it starts, and rotate it 1 time each way and see how that works too.

[rlmergeuser]

I don't think a plank of wood can stop that hinge, especially when it's moving an I beam. I did not try that though so I will give it a shot.

[lespritdelescal]

I don't think it'll stop it either.. if it does, I think it might cause things to go all weird. I'm pretty sure I know how to build this, but it'll have to wait until after the hockey game.

You can try this yourself:

1. Use method two and glue a Dummy object between the force rotation and the i-beam. If you turn off the physics on the force rotation after you glue things together, make sure you select only the hinge and not the entire thing (either the left or right bumper lets you do this).

Glue the opposite side of the force rotation to a Dummy object, and then to any object in the area that will not have physics enabled. This will act as an anchor for the hinge.

Make sure physics is enabled on everything else other than the hinge and the anchor before the track starts. When you trigger the physics on the hinge, again make sure that you are selecting only the hinge. Turning physics on for the entire thing may cause it not to work, or to fall.



If you look very closely at the force rotation, you should be able to see little arrows on it. I really hope I'm not imagining that.. I'm pretty sure it's there though.

[rlmergeuser]

Thanks for the tip lesprit.

I've never used Dummy objects before so I will try that, but there is one part of your description I do not understand.

"Glue the opposite side of the force rotation to a Dummy object, and then to any object in the area that will not have physics enabled. This will act as an anchor for the hinge."

Wouldn't gluing the dummy object to an object without physics enabled cause the entire system to not work?

I won't be able to test this for a little while, I came home to the three flashing red lights on my X Box today. Sending it out for replacement.

[lespritdelescal]

Thanks for the tip lesprit.

I've never used Dummy objects before so I will try that, but there is one part of your description I do not understand.

"Glue the opposite side of the force rotation to a Dummy object, and then to any object in the area that will not have physics enabled. This will act as an anchor for the hinge."

Wouldn't gluing the dummy object to an object without physics enabled cause the entire system to not work?

I won't be able to test this for a little while, I came home to the three flashing red lights on my X Box today. Sending it out for replacement.

Sorry to hear about your XBOX When you get back, give this a go.

I did test this out, and when I did it the way you mentioned, it gave me the same result you said it did. When I did it the way I suggested, it worked. Here is a photo of what I did.



It's hard to see, but at the very bottom, there is a plank of wood, which is the anchor. I then put a dummy on top of that, a force rotation, another dummy and the small I-beam on the top.

After all that is set up, I turn physics on for the I-Beam and off for the force rotation. I then glue everything together. Everything is simply glued to the thing(s) next to it.

Once it's all glued, grab a trigger, check Physics, and click on the force rotation when selecting objects. Hit B to confirm, and test your track. You should be able to ride through the trigger, and start the rotation.

[rlmergeuser]

Lesprit, that looks awesome.

I can't wait to give it a try on my new track.

Thanks a bunch. As for the Xbox... still haven't received the box to send it back in... The UPS label they sent me via email shows the place and it's really close to where I live too, what a bummer.

[rlmergeuser]

i've had the same problem with my ball maze track, and it was surprisingly simple to cure.

1. set up your rotating object rig like this (sorry for the rubbish diagram, its the best i could do)
[code:1c5vet8n]
-------------- <--rotating object, physics off*
FRT <--force rotation hinge, physics on
--- <--some random small object, physics on
[/code:1c5vet8n]

*if the rotating object is made from more than one thing, glued together, make sure only 1 part of it has the physics off, otherwise, when you turn it on, it will do the usual random explosion

2. from that, you should be able to work out that the random object at the bottom will be spinning round, and the object you want to rotate will be still.

3. set up two triggers that are practically touching each other:
-1st one turns the physics off for the random small object
-2nd one turns physics on for the rotating object

4. this will set the object rotating, and shouldnt give it any of that jolt at the beginning

5. to stop the object, you just do the reverse of step 3 - set up two triggers as close as you can:
-1st turns physics off for the rotating object
-2nd turns physics on for the random small object.

make sure you put the triggers the right way round, otherwise the entire rig will drop slightly every time you activate it

hope this helps, because it took me a while to solve this problem myself

[rlmergeuser]

i've had the same problem with my ball maze track, and it was surprisingly simple to cure.

1. set up your rotating object rig like this (sorry for the rubbish diagram, its the best i could do)
[code:1ayd3gtu]
-------------- <--rotating object, physics off*
FRT <--force rotation hinge, physics on
--- <--some random small object, physics on
[/code:1ayd3gtu]

*if the rotating object is made from more than one thing, glued together, make sure only 1 part of it has the physics off, otherwise, when you turn it on, it will do the usual random explosion

2. from that, you should be able to work out that the random object at the bottom will be spinning round, and the object you want to rotate will be still.

3. set up two triggers that are practically touching each other:
-1st one turns the physics off for the random small object
-2nd one turns physics on for the rotating object

4. this will set the object rotating, and shouldnt give it any of that jolt at the beginning

5. to stop the object, you just do the reverse of step 3 - set up two triggers as close as you can:
-1st turns physics off for the rotating object
-2nd turns physics on for the random small object.

make sure you put the triggers the right way round, otherwise the entire rig will drop slightly every time you activate it

hope this helps, because it took me a while to solve this problem myself

Nice! I am sort of surprised I did not think of this myself, simple yet effective.