Attenuation Texture

public static Texture2D MakeAttenuationTexture(int w, float pow, float scale) {
    var bd = new Color[w * w];
    for (int i = 0; i < bd.Length; i++)
    {
        bd[i] = new Color(0,0,0,0);
    }
    /// 1.0 / (1.0 + 25.0*r*r)
    for (int x = 1; x < w - 1; x++)
    {
        for (int y = 1; y < w - 1; y++)
        {
            float actualX = 2.0f * ((float)x - ((float)w) / 2.0f) / (float)w;
            float actualY = 2.0f * ((float)y - ((float)w) / 2.0f) / (float)w;
            Vector2 vec = new Vector2(actualX, actualY);
            float distance = vec.magnitude;
            float attenuation = 1.0f / (1.0f + 25.0f * Mathf.Pow(distance, pow) * scale);
            Color c = new Color(attenuation, attenuation, attenuation, attenuation);
            bd[x + y * w] = c;
        }
    }
    Texture2D newtex = new Texture2D(w, w);
    newtex.SetPixels(bd);
    newtex.wrapMode = TextureWrapMode.Clamp;
    newtex.Apply();
    return newtex;
}