Update Model Parameters

Updated: 09/04/2019

This section is an explanation of the methods and notes on updating parameters attached to the model.

Summary

In Cubism 2.1 for Unity, it was necessary to update parameters by calling .update() after changing parameters with .setParamFloat(), etc.
In Cubism 3 and later versions of the Cubism SDK for Unity, updates are automatically performed from scripts attached to GameObjects generated by ToModel().

In addition, parameters can be updated from a separate script using parameter.value = value;.
Note that the parameters must be updated using LateUpdate() from Unity’s event function execution order.
The same care should also be taken when setting the order in which scripts are called in ScriptExecutionOrder.

Details

How to update with Cubism 2.1 SDK for Unity

In Cubism 2.1 SDK for Unity, updating parameters required calling the following method to perform the update.

void Update()
{
	live2DModel.setParamFloat("Parameter ID", value);
	
	live2DModel.update();
}

In detail, the code was as follows.

void Update()
{
    double timeSec = Time.time;
    double t = timeSec * 2 * Math.PI;

    // Breath
    live2DModel.setParamFloat(breath, (float)(0.5f + 0.5f * Math.Sin(t / 3.2345)), 1);

    // Update parameter values
    live2DModel.update();
}

How to update Cubism 3 or later versions with the Cubism SDK for Unity

In Cubism 3 and later versions of the Cubism SDK for Unity, parameters are automatically updated via CubismRenderController.cs attached to the generated Prefab.
This can be used to update the drawing by applying the values changed by the animation to the parameters.
To apply a value to a parameter, use the following.

void LateUpdate()
{
	parameter = model.Parameters[index];
	
	parameter.Value = value;
}

Examples of specific descriptions are as follows.

using UnityEngine;
using Live2D.Cubism.Core;
using Live2D.Cubism.Framework;

public class ParameterLateUpdate : MonoBehaviour
{
    private CubismModel _model;
    private float _t;

    private void Start()
    {
        _model = this.FindCubismModel();
    }

    private void LateUpdate()
    {
        _t += (Time.deltaTime * 4f);
        var value = Mathf.Sin(_t) * 30f;

        var parameter = _model.Parameters[2];

        parameter.Value = value;
    }
}

This is the code used in the GIF described below.

model.Parameters[index] is set to “2” because the parameter PARAM_ANGLE_Z of koharu is the second (starting from 0).

Note that LateUpdate() must be used when updating parameters from a script using Cubism 3 or later of Cubism SDK for Unity.
Unity animations are processed after Update(). Therefore, changing the value of a parameter within Update() will overwrite the animation.
To work around this, the parameters must be updated using LateUpdate(), which is called after the animation process is complete.

The following GIF shows a Scene in which the PARAM_ANGLE_Z value is manipulated from a script on a model playing an animation.
The left model manipulates parameter values from Update() and the right from LateUpdate(), and you can see that the left one has had its value changes overwritten.