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The MMD Physics Engine keeps Skirts from going through legs!

An MMD Feature Article by Winky on LearnMMD.com!Why does my model look so stiff? Can I adjust the MMD Physics Engine to automatically take care of my model’s fabrics and hair? Do I always have to adjust every bone in the model in order to get a natural pose?


How to keep Skirts from going through legs …
Adjust Gravity & Wind Effects …

Adjust The MMD Physics Engine!

Set the Physics Settings for a Natural Pose

Have you ever opened up MMD and decided, With the Physics turned off ... almost nothing on your model will look natural.“Hey, I’m going to pose  a model with a skirt, sitting on a chair!” and have this happen.


Oh noes! Now we have to take each skirt bone and individually adjust it! That will take forever!

Actually, there’s a fancy trick to fixing this.







Open the Physical Operations Tab to make adjustments to your physics settings.

First, before you sit the model down, turn the Physics settings on. Don’t know how? Let’s adjust the MMD Physics Engine.  Click the “Physical Operation (P)” tab, and then click anytime (To turn it back off, just select “Only Playtime” or “No Calculation”).




With the Physics switched "on", your model will look more natural with little effort!



Now gently sit your model back down again and…voila! No tedious work!








Sometimes your beautiful pose needs a little something to make it more dramatic ...



While I’m still on the subject of the Physics Engine, why not talk about wind? Say I pose a model in a nice little pose, like this…

…But I want to make it more dramatic, so I decide to add some wind, but how?





You can create "wind" by adjusting the directions of the Gravity settings.

Easy. Go back to the Physical Operation tab and click gravity settings. After you do, something like this should come up.




Wow! ... The "wind" adds so much life to your model's appearance.


Now, it’s time to adjust the wind.
-slide along the X axis for the wind to go LEFT and RIGHT
-slide along the Y axis for the wind to go UP and DOWN
-slide aling the Z axis for the wind to go FORWARD and BACKWARD

This was the final outcome.




Careful ... your model will look bad if you turn off the physics!


On a final note, if you use a PMD model, don’t turn the physics off unless you want to start over with them because this will happen.

If you turn the physics engine off with a PMX model, the bones will not reset.





Also, in case any of you are curious, this is what the tabs on “Physical Operation” mean.
-Anytime: The physics are on at all times.
-Only Playtime: The physics are on only when you play an animation.
-No Calculation: The physics are off at all times.
-Display Bodies: Allows you to see the “physical physics”.
-Initialize Bodies Position: Not quite sure. If you know tell me.
-Floor: Click to make the floor not be affected by gravity. For example, if you sit a model down on the floor his/her dress will fall through instead of spread out.

Model Credits:
Sweet Ann: Saboten (さぼてん)
Chair: 3D-Custom Girl, ripped by 9844.deviantart.com


Visit the LearnMMD.com Homepage! Plenty of Mikumikudance instruction and info!


  1. November 7, 2016    

    hiz! so, i have tried everything, and the ones u said in the comments section but my model’s legs keep going thru plz help!!

  2. Justcommenting Justcommenting
    August 10, 2016    

    Initialize Bones mean if you want to reset the physics to their original placement, like if you would put on no calculation then anytime.

    • Jasper Jasper
      April 1, 2017    

      You mean Initialize physics right? not bones. Initialize physics also Resets physics when they get tangled while running the motion, yet it is absolutely useless because hitting the shortcut ‘I’ to initialize while rendering to video, does nothing. (a bug ignored with every update) So you wind up having to do countless renders until your video might randomly come out OK without the skirt physics screwing up on that particular dance motion not friendly to even, the most advanced skirts.

  3. Nico nico nii Nico nico nii
    May 23, 2016    

    Hi! I downloaded a really nice motion but everytime i try to use it (the motion has the model sitting down) the legs glitch right through the skirt or dress. It also happens with all other sitting down motions or poses that I downloaded. How can i fix this?

    • May 23, 2016    

      Does this happen because the skirt doesn’t move at all along with legs (in which case this article is the answer), or it does but small patches of skin still protrude through fabric? If so, you’d have to edit the model in PMDE. Single out the material that contains legs, select the part that you’re not supposed to see because of the dress, and shrink it somewhat (no need to erase it completely). Save the model under a different name, so that if something goes wrong, you can revert to the original.

  4. aquarin02 aquarin02
    May 28, 2014    

    I really need help with the physics. When I try to add physics to my model’s clothes, then load it into MMD to test it, my model would just… fall down. How do you add physics so things like that won’t happen?

  5. Priya Priya
    January 31, 2014    

    I have a problem. Please help as soon as possible. I have been working on a model all day long and I used a base. But now I just removed the top and it takes the body part underneath with it. If I don’t remove the top, I can’t let het wear what I want, like swimsuits and low cut dresses. The breasts above the top also have holes; you can look right through it. Is it possible for me to remove that darn top and replace the chest and the belly it takes down along with it? I would like to know how I can give her “new” breasts and a new belly once it’s gone and how to attach it to the rest of the body to make it move along smoothly. I am a beginner so I don’t know how. Please help me?

    • Reggie_Dentmore Reggie_Dentmore
      February 1, 2014    

      Help is on the way … I have emailed our 15 writers … someone will be back to you shortly “:o).

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