URP打开半透明阴影（一百二十七）

    Properties
    {
        //....

        [Toggle]_TShadow("TShadow", Float) = 0
    }
    //....
    CustomEditor "MyLitShader"

    private MaterialProperty tShadow;
    public override void FindProperties(MaterialProperty[] properties)
    {
        base.FindProperties(properties);
        litProperties = new LitGUI.LitProperties(properties);
        tShadow = BaseShaderGUI.FindProperty("_TShadow", properties, false);
    }

    public override void DrawSurfaceInputs(Material material)
    {
        base.DrawSurfaceInputs(material);
        LitGUI.Inputs(litProperties, materialEditor, material);
        DrawEmissionProperties(material, true);
        DrawTileOffset(materialEditor, baseMapProp);


        //绘制半透明阴影
        SurfaceType surfaceType = (SurfaceType)material.GetFloat("_Surface");

        if(surfaceType == SurfaceType.Transparent)
        {
            materialEditor.ShaderProperty(tShadow, "半透明阴影");
            material.SetShaderPassEnabled("ShadowCaster", (material.GetFloat("_TShadow") == 1.0));
        }
        else
        {
            material.SetShaderPassEnabled("ShadowCaster", true);
        }
    }