Unity 过度光照贴图

背景：开关窗帘过程，让环境在亮和暗之间过度

事先烘培出亮、暗两张Lighting map。然后代码实现，窗帘开关由动作实现，而代码中通过动作执行进度来过度两张Lighting map

void OnAnimatorMove()
{
    AnimatorTransitionInfo transitionInfo = animator.GetAnimatorTransitionInfo(0);
    if (transitionInfo.normalizedTime != 0)//状态切换中
    {
    }
    else
    {
        AnimatorStateInfo currentAnimatorStateInfo = animator.GetCurrentAnimatorStateInfo(0);

        // 开窗
        if (currentAnimatorStateInfo.IsName("opening"))
        {
            LightmapBlender.Instance.OpenWindow(currentAnimatorStateInfo.normalizedTime);
        }

        // 关窗
        if (currentAnimatorStateInfo.IsName("closing"))
        {
            LightmapBlender.Instance.CloseWindow(currentAnimatorStateInfo.normalizedTime);
        }
    }

public Texture2D normalTexture2D;
public Texture2D closeWindowTexture2D;
public Texture2D dancingTexture2D;

public Texture2D blendTexture2D;

private Color[] normalColors;
private Color[] closeWindowColors;
private Color[] dancingColors;

private Color[] blendColors;

[SerializeField]
private Transform brightTransform, darkTransform;

[SerializeField]
private Color brightAmbientLight, darkAmbientLight;

void Awake ()
{
    normalColors = normalTexture2D.GetPixels();
    closeWindowColors = closeWindowTexture2D.GetPixels();

    if (dancingTexture2D != null)
        dancingColors = dancingTexture2D.GetPixels();

    blendColors = blendTexture2D.GetPixels();
}

public void OpenWindow(float t)
{
    brightTransform.gameObject.SetActive(true);
    darkTransform.gameObject.SetActive(false);

    Blend2Textures(closeWindowColors, normalColors, t);
    RenderSettings.ambientLight = Blend2Color(darkAmbientLight, brightAmbientLight, t);
}

public void CloseWindow(float t)
{
    brightTransform.gameObject.SetActive(false);
    darkTransform.gameObject.SetActive(true);

    Blend2Textures(normalColors, closeWindowColors, t);

    // 过度环境光（影响没烘培在Lighting map 中的对象的明暗）
    RenderSettings.ambientLight = Blend2Color(brightAmbientLight, darkAmbientLight, t);
}

private Color Blend2Color(Color from, Color to, float t)
{
    Color blend;

    blend.r = from.r * (1 - t) + to.r * t;
    blend.g = from.g * (1 - t) + to.g * t;
    blend.b = from.b * (1 - t) + to.b * t;
    blend.a = from.a * (1 - t) + to.a * t;

    return blend;
}

private void Blend2Textures(Color[] from, Color[] to, float t)
{
    for (int i = 0; i < blendColors.Length; i++)
        blendColors[i] = Blend2Color(from[i], to[i], t);
    
    blendTexture2D.SetPixels(blendColors);
    blendTexture2D.Apply();

    SwitchLightmaps(blendTexture2D);
}

private void SwitchLightmaps(Texture2D tex)
{
    LightmapData[] lightmaps = LightmapSettings.lightmaps;
    
    lightmaps[0].lightmapFar = tex;

    // 切换 Lighting map
    LightmapSettings.lightmaps = lightmaps;
}