stencil in unity3d

Pass {
            Stencil {
              Ref
              Comp Always
              Pass REPLACE
            }

            AlphaTest Greater
            Blend SrcAlpha OneMinusSrcAlpha
            Color[_Color]
            SetTexture[_MainTex] {
                Combine texture
            }
        }

        // render outline

        Pass {

            Stencil {
                Ref
                //Comp Always
                Comp NotEqual

            }

            Cull Off
            ZWrite Off

            AlphaTest Greater 0.9
            Blend SrcAlpha OneMinusSrcAlpha
...
}