//_GreyColor("GreyColor", Color) = (0.299, 0.587, 0.114,1)
if (i.color.r < 0.001)
{
col = tex2D(_MainTex, i.texcoord);
float grey = dot(col.rgb, float3(_GreyColor.r,_GreyColor.g,_GreyColor.b));
col.rgb = float3(grey, grey, grey);
}
else
{
col = tex2D(_MainTex, i.texcoord) * i.color;
}