How to set up physics operations

(Updated 10/28/2021)

 

This page describes the basic physics setup procedures.
See Physics Settings for details on the Physics Settings screen.
The physics calculation settings are saved in the model data (cmo3), so please save the model data after setting.
However, even if the physics setting screen is closed as is, the settings are retained.

POINT
When shaking is controlled by physics, it is necessary to prepare parameters with shaking motion in advance.

 

Procedure for setting up physics calculations

Open the physics setting screen

Click [Modeling] menu -> [Physics and Scene Blend Settings] to open the Physics Settings dialog box.
If physics is not set, the setting item will be grayed out and the operation will be disabled.

Create a group

Number Item Detail
(1) Click [Add] to open the [Add Group] dialog.
(2)   Enter a [Name], and choose whatever you want for [Presets for Inputs] and [Presets for Physical Model].
When settings are complete, click [OK].

Groups can be created even if [Input Presets] and [Physical Model Presets] are left unset.
This item can also be changed after the group is created.

 

Set output parameters

Number Item Detail
(1) Set the sway parameter to work with the created group.

Click the [Output Settings] tab to switch to the Output Settings screen.

(2)   Click the [Add] button (A) to open the [Output Parameters] dialog.

From the [Output Parameters] dialog, select the parameter you want to move and click the [OK] button (B).

(3) Drag the view area to move the model's face and body to follow the cursor.
It also reacts when the parameters set for the input are moved from the list.
Make sure that the shaking you have set up is working properly.

 TIPS
If the [Enable Physics] checkbox in the playback bar is unchecked, physics will not be enabled.
Check this box when you want to check the physics movement.

From here, we will explain how to adjust the sway.

 

Change input settings

In physics operations, changes in the values of the parameters set as input will cause fluctuations in the parameters set as [output].
Even for the same movement, changing the input settings will change the way it shakes.

 

Change input parameters

The preset has “Angle X”, “Angle Z”, “Body Rotation X”, and “Body Rotation Z”, but
it is also possible to set the input parameter to another parameter.

For example, by setting the input parameter to “Body rotation Y,” you can make the hair fluff up during the jumping motion.
If the arms have accessories, they can be shaken by setting arm-related parameters as input parameters.

 

Change in Impact

The same input parameter will change the sway when the influence level is changed.

The following table shows a case, for the same model with the same motion, physical model settings, and output parameter settings,
in which only the influence of the input parameters “Angle X” and “Body rotation X” was changed.

This setting is for the “Angle X” setting with a weaker influence of “Angle X” and a stronger influence of “Body Rotation X”.
The “body rotation X” during motion is weak, so the hair and ribbons hardly sway.
This setting makes the influence of “Angle X” stronger and the influence of “Body Rotation X” weaker.
The “Angle X” during the motion is strong, so the hair and ribbons sway well.

Thus, differences in the influence of inputs also have a significant impact on sway.

 

Change physical model settings

In the physical model settings, the speed of shaking and reaction time can be adjusted.

 

Duration

In [Duration], you can adjust the speed of the shaking.
The smaller the value, the quicker the movement; the larger the value, the slower the shaking.
If you want to change only the speed without changing the amount of change in the parameter value, adjust the [Reaction Speed] item.

[Duration] value Small Big
Shaking Changes

Quick

Slowly
Pendulum Preview

 

Shakiness

In [SHAKING EASE], you can adjust the amount of shaking.
The larger the value, the larger the swing will be for even a small input.
As a rule of thumb, use a setting in the range of 0.7 to 0.99.

[Shakability] value Small Big
Shaking Changes Shake resistant shaken easily
Pendulum Preview

 

Reaction velocity

Under [Reaction Speed], you can adjust the reaction speed of the shaking. This is a setting for how agilely it responds to input.
The response is equal at “1”; greater than “1” makes it more agile, and less than “1” makes it less responsive.
If the pendulum is multi-staged, the setting is based on how agile this pendulum is in response to the movement of the parent pendulum.

[Reaction speed] value Small Big
Shaking Changes Slow to react Quick to respond
Pendulum Preview

 

Convergence speed

In the [Speed of Convergence] section, you can set how quickly the shaking will subside.
The convergence is equal at “1”. If it is greater than “1”, the convergence is faster, and if it is less than “1”, the convergence is slower.

[Speed of convergence] value Small Big
Shaking Changes Slow Fast
Pendulum Preview

 

Adjusting output settings

The shaking calculated in the [Input Settings] and [Physical Model Settings] will be applied to the parameters set in [Output].
Under [Maximum Output (%)], you can see what percentage of the destination parameter has moved from 0 to the maximum value.
In addition, the [Scale] can be set to any value to adjust the magnitude of shaking, or it can be adjusted automatically according to the [Maximum Output (%)].

Magnification adjustment

The [Scale] can be set to any value to adjust the magnitude of the shaking.
To reduce sway, set [Scale] to a value less than “1”; to increase sway, set it to a value greater than “1”.

However, if the shaking is too great, the parameter may swing out.
In that case, we recommend using [Output Adjustment (Down)].
For details on [Output Adjustment (Down)], please refer to the “Automatic Output Adjustment” section below.

Tips
The magnitude of the shaking is also affected by the [Input Settings] and [Physical Model Settings].
If the shaking is small, please review the settings there as well.

 

Automatic adjustment of output

Check the movement of the output parameters by cursor tracking and scene playback before automatically adjusting the output.
Then check the value of [Maximum output (%)].

POINT
[Maximum output (%)] indicates the percentage movement of the output value obtained by multiplying the input by the
maximum value of the destination parameter from 0 to the maximum value.

    Let's take the case where the default value is 0 with the parameter settings as shown in the figure below.

    
    * Input normalization is not performed in this example.

 

If the maximum output is well below 100% (small movement):

The maximum output represents how much the output parameter was running.
As shown in the figure below, when [Maximum Output (%)] is set to 50%, only about half of the movement attached to the parameter is in motion.
If you want to increase the motion, click [Output Adjustment (Up)] to automatically adjust the output.

After auto adjustment, [Scale] will be adjusted so that [Maximum Output (%)] is set to 100%.
This allows the sway movement to be increased within the proper range.

 

If the maximum output is well above 100% (if the movement is swinging out of control):

The maximum output represents how much the output parameter was running.
If [Maximum Output (%)] exceeds 100%, the swing of the pendulum is out of the range of the parameter.
The pendulum is trying to move to a range where it is not creating movement, which causes crackling.
If you want to reduce the motion, click [Output Adjustment (Down)] to automatically adjust the output.

After auto adjustment, [Scale] will be adjusted so that [Maximum Output (%)] is set to 100%.
This reduces output and eliminates crackling.

 

Redo output adjustment

If you do not get the result you want during adjustment, you can reset the output result by clicking the button below.

Reset scale:
Resets the adjusted magnification to “1.0”.

Reset maximum output:
Resets the value of the maximum output detected by cursor tracking and scene playback.

 

How to set up applied physics operations

Set the pendulum in multiple steps

This section describes the procedure for setting up applied physics operations such as multi-stage pendulums and skinning swings.
Please refer to the “Skinning page for skinning settings.

Number Item Detail
(1)   Add a physics group.
For [Physical Model Preset], select “Hair 2-step pendulum,” “Hair 3-step pendulum,” “10-step,” or “20-step”.
* Preset should be determined by the number of parameters for shaking.
(2)   Switch to the [Output Settings] tab to set output parameters.
Select all output parameters from the [Output Parameters] dialog.
You can select a range by pressing [Shift]+click.
(3) In the [Physical Model Settings], check that the number of parameters used for output matches the [No.] in the [Pendulum Settings].

For example, if you use a “10-step” preset with 5 parameters used for output, [Delete] the pendulum after “6” in [No.].
Conversely, if there are not enough pendulums for the parameters to be used for the output, [Add] should be used.

Note that even if the pendulum is set to multiple steps in the [PHYSICAL MODEL SETTINGS], it will not swing cleanly if the [Pendulum No.] in the [OUTPUT SETTINGS] is all set to “1” or if the numbers are misaligned.

(4) Cursor tracking and scenes are played back to check for shaking.


TIPS

Even if the sway parameters are divided between left and right, they can be set together in one group by setting them as shown in the image.

 

Skinning magnification adjustment

If [Output Adjustment (Up)] is used for skinning, the value will be too large for the parameters set by skinning, and
the parameters will be swept out.
If skinning is set to a multi-step setting of about 10 steps, setting the magnification factor to around “20” will result in optimal movement.
To change the magnification factor for multiple output parameters at once, right-click on [Scale] and select [Change Value Batch].

 

Output Inversion

In the case of a swaying object that is divided into left and right parts, the motion can be inverted to express a fluffy, spreading motion.
To invert the motion, go to [Output Settings] and check the [Reflect] checkbox for the parameter to be inverted.

Tips
If the same parameter is set as an output in multiple groups,
Be sure that the total [Influence] in the [OUTPUT SETTINGS] section does not exceed 100%.
If the [Influence] value exceeds 100%, the parameter will be out of balance, resulting in jerky motion.

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