1. #1
    nannerdw's Avatar Senior Member
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    Jan 2013
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    Multi-part physics objects?

    I'm trying make a large moving object with several connected parts. I want the whole thing to rotate as one solid piece, but enabling physics makes each piece shake around from the collision detection between the parts. Even when the parts not touching, the connections between the glued parts are too loose and make everything wobble. Is there a way to make it treat the whole glued piece as a single physical object?
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  2. #2

    Re: Multi-part physics objects?

    I'm having trouble with this too, so consider this a bump.

    What I wanted was a steel ramp plate with a sign glued to it to fall over slowly due to gravity, but I wanted it triggered at a particular moment.

    If I glue the two together, the combination will only fall if the trigger is set to start physics on both of them. But in this case, the sign then falls off of the plate (becomes unglued).

    There doesn't seem to be a way to make them fall as a single unit. Am I missing something?
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  3. #3

    Re: Multi-part physics objects?

    The only way I have managed to keep things together like that is by using hinges.
    Glueing seems to do nothing except let you move about the structure as a whole but the moment physics is on it just crumbles apart.
    Try using a hinge between the post and the sign and have a trigger to enable the physics and see if that works.
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  4. #4

    Re: Multi-part physics objects?

    The hinge does work. But it's too bad that is necessary.

    The actual problem seems to be with the trigger itself, as having the construction already with physics turned on works as intended. The trigger doesn't work on the entire construction, only on individual parts, and for some reason, that tends to pop apart the build into its constituent pieces. I think this could be labeled a bug.
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  5. #5

    Re: Multi-part physics objects?

    What happens if you have two triggers set up, one for the movement of the item and the second for the sign?
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  6. #6

    Re: Multi-part physics objects?

    Originally Posted by Yourmum90
    What happens if you have two triggers set up, one for the movement of the item and the second for the sign?
    This still doesn't solve it. Whether you use one trigger on all of the parts, or one trigger each, the moment it goes, everything comes unglued.

    The only solution is to turn physics on for each part that makes up the multiple part object, and forgo the trigger. If it needs to be timed, you can create a small separate object that holds the whole thing in place and trigger that to fall out of the way, explode, or the like.
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  7. #7

    Re: Multi-part physics objects?

    I have just been experimenting with this and still can't find a proper solution.
    Like you say if you make an object, for example, a sign with a post, glue them together, rotate it slightly and enable physics it will fall together like it should do.
    BUT
    The moment you bring a trigger into play which enables the physics of the whole object it just falls apart.
    I wanted to make a lift like the start of "Dynamic Range" but just can't figure out how they did it. I haven't noticed anything underneath the lift which allows it to drop.
    Puzzling to say the least but maybe it could be patched to allow a glued object to selected as a whole when using triggers.
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  8. #8

    Re: Multi-part physics objects?

    I created a cart on my Concrete Causway level, which I wanted to move when triggered that the rider was on it but, like mentioned above the trigger made the cart fall apart into individual pieces. I got around it by having physics enabled on all parts and wedging the front wheel with a plank.
    A trigger was then placed just where the rider and bike would sit on the cart and it triggered Explode/Break apart on the plank, thus removing the wedge and the cart started rolling...
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  9. #9

    Re: Multi-part physics objects?

    Originally Posted by Skysaw
    I'm having trouble with this too, so consider this a bump.

    What I wanted was a steel ramp plate with a sign glued to it to fall over slowly due to gravity, but I wanted it triggered at a particular moment.

    If I glue the two together, the combination will only fall if the trigger is set to start physics on both of them. But in this case, the sign then falls off of the plate (becomes unglued).

    There doesn't seem to be a way to make them fall as a single unit. Am I missing something?

    here's a tutorial to do this:

    1. First glue your objects. Note that PHYSICS will have to be on for the top object, and that objects on top will have to be able to balance at rest normally or IT WILL BREAK THE GLUE. to test whether it will break the glue work on your construction using the physics testing feature on the top objects. if they're falling it won't work. if they're in place will work. you may have to redesign your structure to find something that will stay glued.

    2. Now that you have glue rigged safely, make sure that the bottom object has no physics turned on, while the top object has it on.

    3. Make a trigger that only connects to the bottom object. Select physics, so when the trigger is hit the bottom object turns physical.

    now it will work, as the glue stays permanent at this point, and both objects stay together. I used it to add a platform glued to a flipper.
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  10. #10

    Re: Multi-part physics objects?

    Originally Posted by radica1travis
    ...Note that PHYSICS will have to be on for the top object, and that objects on top will have to be able to balance at rest normally or IT WILL BREAK THE GLUE.
    That wouldn't work in my case, since I needed the steel plate to be off balance so that it would slowly fall over.

    I think the fact that glue can break at all points to a programming bug.
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