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I'm new to Blender and I'm making a simple animation and I want an object to stand on plane. I have a plane aligned with 0 on z-axis with passive rigid body. I placed an object on the plane so that the bottom lines up with z=0, but when I add the active rigid body to the object in the first couple frames it falls slightly below the plane and stops there(around -0.1), instead of stopping on the plane. It's as if Blender was thinking that my plane is at -0.1 but it's at 0. I applied all the transforms to both the object and the plane. Any idea why is that happening and how to fix it?

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    $\begingroup$ hello, could you please share your file? pasteall.org/blend $\endgroup$
    – moonboots
    Jul 6 at 10:01
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    $\begingroup$ as you can see in the comments, your information is not enough. Gorgious assumes your center points are not correct, i assume you have used convex hull....so the best is to provide all information we need to help you. This you could either do by providing your blend file (so we can checkout everything and help you) or you provide screenshots of all relevant settings (rigid body of all objects, center points etc) but at least we are just "guessing around" $\endgroup$
    – Chris
    Jul 6 at 10:11
  • $\begingroup$ Thanks for the replies. Here is the blend file: link The object I'm talking about is the bowling pin going slightly below the plane in the first 3 frames. I tried changing it from Convex Hull to Mesh but then the pin jumps up $\endgroup$
    – Rianna
    Jul 6 at 10:39
  • $\begingroup$ @Rianna Changing to Mesh automatically enables the Sensitivity > Margin with a default setting of 0.04 m - since your pin is closer to the floor than 0.04 m, it jumps. So you have to set it lower, but as described in my answer, changing (only) the floor won't help. Also, Mesh lets Blender calculate the collision more accurately which is especially important with intersecting meshes like chain links, but for a bowling pin Convex Hull is perfectly fine since there are no intersections. $\endgroup$ Jul 6 at 11:28
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To make your bowling pin stand on the ground, simply activate Collision Margin under the Rigid Body Properties > Sensitivity and set it to 0. You can do this additionally for the floor as well, but it's not necessary (note: enabling it only for the floor and not the pin doesn't help).

By the way: the face normals of your pin are pointing inwards, to correct it go into Edit Mode, select all by pressing A, then Shift+N to Recalculate Normals. (But this is not the reason for the rigid body behaviour).

collision margin

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  • $\begingroup$ Thank you, that solved it!!! Well spotted with the normals, I completely forgot to check that! $\endgroup$
    – Rianna
    Jul 6 at 11:15
  • $\begingroup$ @Rianna I just checked them as a possible cause, but it turned out they didn't matter in this case. You might consider accepting the answer. $\endgroup$ Jul 6 at 11:21
  • $\begingroup$ @GordonBrinkmann I didnt check the file, but Normals should matter for RB ... inverted normals explains why object appeared under Plane and not above 0.04 as set in Margine (as usual) :) $\endgroup$
    – vklidu
    Jul 6 at 14:32
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    $\begingroup$ There is some weird relationship between skittle's bottom size and amount of "penetration. It is not happening with Cube and also when skittle's bottom face is size of the widest part imgur.com/4IX1GAQ ... make it smaller - make it deeper bellow Plane :) ... it doesn't happen for collision shape > Mesh, where Margin is activated by default. According to "Convex Hull" boundary it doesnt make a sense to behave like this ... also Sphere or Ovoid works fine imgur.com/aNtlxwc ... now I'm totally lost :) $\endgroup$
    – vklidu
    Jul 6 at 16:21
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    $\begingroup$ @vklidu I don't really understand it either, sometimes I think this all works a little counter-intuitive from time to time... $\endgroup$ Jul 6 at 19:17

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