Ios 金属功能

我有下一个功能：

float4 blur(float rad, texture2d<float> tex2D, sampler sampler2D, float2 textureCoordinate){    
    float width = tex2D.get_width();
    float height = tex2D.get_height();
    float weight = 1 / ((2 * rad + 1) * (2 * rad + 1));
    float4 blured_color = float4(0,0,0,0);
    for(int i = -1 * rad; i <= rad; i++){
        for (int j = -1 * rad; j <= rad; j++){
            blured_color += tex2D.sample(sampler2D, textureCoordinate + float2(i/width, j/height)) * weight;
        }
    }
    return blured_color;
}

float4模糊（float-rad，texture2d-tex2D，sampler-sampler2D，float2-texturecoordination）{
float width=tex2D.get_width（）；
浮动高度=tex2D.get_height（）；
浮子重量=1/（（2*rad+1）*（2*rad+1））；
float4模糊颜色=float4（0,0,0,0）；
对于（int i=-1*rad；i
fragment float4 blured_background_fragment(VertexOut        interpolated [[ stage_in ]],
                                    texture2d<float> tex2D        [[ texture(0) ]],
                                    sampler          sampler2D    [[ sampler(0) ]])
{
    float4 color = tex2D.sample(sampler2D, interpolated.textureCoordinate);
    float3 color3 = float3(color[0] , color[1] , color[2]);
    if (is_skin(color3) && !(interpolated.color[0] == 1 && interpolated.color[1] == 1 && interpolated.color[2] == 1)){
        float width = tex2D.get_width();
        float height = tex2D.get_height();
        float rad = 13;
        float weight = 1 / ((2 * rad + 1) * (2 * rad + 1));
        float4 blured_color = float4(0,0,0,0);
        for(int i = -1 * rad; i <= rad; i++){
            for (int j = -1 * rad; j <= rad; j++){
                blured_color += tex2D.sample(sampler2D, interpolated.textureCoordinate + float2(i/width, j/height)) * weight;
            }
        }
//        Here I try to call this blur function     
//        float4 blured_color = blur(13, tex2D, sampler2D, interpolated.textureCoordinate);
        return blured_color * 0.43 + color * 0.57;
    }
    else{
        return tex2D.sample(sampler2D, interpolated.textureCoordinate);
    }
}