Physics simulation

December 7, 2012

MMDAgent has a physics engine to simulate natural-looking movements of models.  The simulation is applied to models that contain extra definitions of rigid bodies and joints.  MMDAgent adopts the same engine as MikuMikuDance, so any physics-enabled models for MikuMikuDance can be used in MMDAgent.  The major differences in MMDAgent are:

  • The default gravity scale factor of MMDAgent is 2.0, and that may cause a feeling of the object being floating on air during simulation, if compared to MikuMikuDance.  Setting the factor to 10.0 will make the simulation closer to MikuMikuDance.  You can change the gravity scale by writing “gravity_factor=2.0”  in the configuration file (.mdf).
  • The rigid body of the floor (XZ plane) does not exist in the simulation.

Pressing “Shift+W” key in the window toggles the debug display of the rigid bodies.  The colors of the rigid bodies are based on their bone-association type.  Also pressing the “P” key will pause / resume the physics simulation, while keeping the physics status when paused.

=== Japanese ========================================


  • 重力係数の倍率が異なります.MMDAgent のデフォルトは2.0 で,MikuMikuDanceに比べ浮いているように感じるかもしれません.10.0とするとMikuMikuDance に近い挙動になります.設定するには設定ファイル(.mdf)の中に「gravity_factor=2.0」のように値を指定します.
  • 床(XZ平面)には剛体が入っていません.