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Thread: Dmm problems

  1. #1

    Dmm problems

    while working with DMM came across a problem . the objects are floating in the air after collision , i have used a splinter image file for the fragments , pls help

  2. #2
    problem here to me seems to be the simulation rate. Open your default DMM scene settings and change the value of substep to something way higher like 128 or 256. Space scale may need to be adjusted too.
    good luck

  3. #3
    Your problem looks to be one of splinters vs tets. If your splinters are too large, they will stick out of the tets and the result will be exactly what you are seeing. Keep your splinter/tet ratio to around 3:1 (3 splinters per every tetrahedron) and you should be OK.


  4. #4
    Could you clarify this a bit for us admin. Not really sure what you mean. so there isnt enough tet information to support the splinters? or there is too many tets within the splintered chunks?

  5. #5
    Splinters are just geometry. They are not simulated, used for collision or physically interactable in any way. The purpose of splinters was originally to add a 3D visual detail to separated tetrahedron faces so that everything didn't look too geometric when it broke. The rule of thumb we have found is that you want about 3 splinters per tetrahedron when you are using splinters. If your splinter is larger than a tet, you will get the strange behavior sandeepsh is seeing. The tet will collide with other tets, but the surface geometry (the splinter) will not reflect that as it will not really be interacted with. Also, since a tet can flex and bend, the splinter will move around in strange ways.

    Basically, you want there to be more splinters per tetrahedron, then the behavior is correct. For wood it even turns out nice since the splinters interpenetrate, creating a "woody" feel.

    If I have time, I'll post a video demonstrating this better.


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