Fixing Sudden Transformation During Simulation

A custom physics structure may contain several connections, such as Constraint, Pick Target or even Attach. However, sometimes these connections may encounter a sudden transformation of the parts in the structure during the simulation, especially when the Attach feature is used to either construct a custom structure or to customize the appearance of the dummies.

If you encounter the flash of a distorted object when you play back to simulate the result or during the rendering export process, then you need to apply the Reset Scale first to the root of the physics structure to fix this problem.

Sudden Transformation after Attaching

1. Construct a custom structure with dummies from the Physics Toolbox.
   
   The original tree structure in the Scene Manager is as shown in the following illustration:
   

   Each part is at the same level of the tree structure.

2. Click the Play button in the control panel to simulate.
3. Select all of the parts and Attach them to a parent (in this case, the board). This step ensure that you may save the structure into the prop Custom library for use again.
   

   Each part is moved under a parent.

4. Go to the start frame and simulate again.

   The sudden transformation happens to the motors when the simulation starts.

Keeping the Attachment Hierarchy and Rectifying the Transformation

At this time, you may face a dilemma: On one hand, you may want to detach all the distorted parts to produce correct animation but as a result be unable to save the structure. On the other hand you may want to use the attach function for saving the structure which may produce incorrect animations.

IClone (the version after 5.13) provides a feature that solves this issue.

1. Pick the Root Node of the structure from the Scene Manager.
   
2. Switch to the Set > Prop > Modify panel.
3. Scroll the panel to the Transform section. Click the Reset Scale button.
   
4. Simulate again and the sudden transformation issue is eliminated.

   Note:

   After using the Reset Scale feature, the original simulated animation will be removed. You need to redo the physics simulation again and the problematic rendering issues will be eliminated. The Reset Scale feature reduces the calculation of the scaling during the rendering, which increases the stability and accuracy of the physics simulation, and reduces the scale distortion issues caused by the attaching function.