Shader alpha depth problem?

Questions & Answers
1

I have this shader for a mobile game:

Shader "Unlit/Transparent" {
 
Properties {
	_Color ("Main Color (A=Opacity)", Color) = (1,1,1,1)
	_MainTex ("Base (A=Opacity)", 2D) = ""
}
 
Category {
	Tags {"Queue"="Transparent" "IgnoreProjector"="True"}
	ZWrite Off
	Blend SrcAlpha OneMinusSrcAlpha
 
	SubShader {Pass {
		GLSLPROGRAM
		varying mediump vec2 uv;
	   
		#ifdef VERTEX
		uniform mediump vec4 _MainTex_ST;
		void main() {
			gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
			uv = gl_MultiTexCoord0.xy * _MainTex_ST.xy + _MainTex_ST.zw;
		}
		#endif
	   
		#ifdef FRAGMENT
		uniform lowp sampler2D _MainTex;
		uniform lowp vec4 _Color;
		void main() {
			gl_FragColor = texture2D(_MainTex, uv) * _Color;
		}
		#endif     
		ENDGLSL
	}}
   
	SubShader {Pass {
		SetTexture[_MainTex] {Combine texture * constant ConstantColor[_Color]}
	}}
}
 
}

My problem is, that I want it like image 3. Now it looks like image 2 :
59399-u-1.png

How can I do it like image 3? The shader alpha must be changeable.

2

You can try with the Stencil Buffer, add this line 12, it seems to work:

Stencil {
    Ref 1
    Comp Greater
    Pass  IncrSat
}

59406-screenshot-2015-12-05-16-17-41.jpg

Note that Stencil buffer is used to compute lighting on opaque objects in deferred rendering, so you may want to clear the buffer with Camera.clearStencilAfterLightingPass if you are not using Forward Rendering Path.

More about Stencil Buffer: http://docs.unity3d.com/Manual/SL-Stencil.html