思路：渲染两次。
1.第一次渲染：利用Greater进行深度测试，当目标被遮挡时，用一个边缘光的效果显示。
2.第二次渲染：正常渲染。
边缘光的思路：观察方向和顶点法向量夹角越大，边缘光越明显。边缘光强度由公式rim=1-dot(view,normal)来表示。
代码实现：
Shader "Pj/XRay"
{
Properties
{
_MainTex("Base 2D", 2D) = "white"{}
_XRayColor("XRay Color",Color)=(,,,)
_SelfBritness("Self Britness",Range(,))=
} SubShader
{
Tags{ "Queue" = "Geometry+233" "RenderType" = "Opaque" } Pass
{
Blend SrcAlpha OneMinusSrcAlpha
//Blend One OneMinusSrcColor
ZWrite Off
ZTest Greater
//Offset -1000,0
CGPROGRAM
#pragma vertex vert
#pragma fragment frag #include "Lighting.cginc"
#include "UnityCG.cginc" sampler2D _MainTex;
float4 _MainTex_ST;
float4 _XRayColor;
float _SelfBritness; struct v2f
{
float4 pos : SV_POSITION;
float4 worldPos:TEXCOORD0;
float3 normal: NORMAL;
//float2 uv : TEXCOORD1;
}; v2f vert (appdata_base v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.worldPos=mul(_Object2World, v.vertex);
//o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
o.normal=v.normal;
return o;
} fixed4 frag(v2f i) : SV_Target
{
float3 normal = normalize(mul(i.normal, (float3x3)_World2Object));
float3 viewDir=normalize(_WorldSpaceCameraPos-i.worldPos).xyz;
float rim = -max(, dot(normal, viewDir));
return _XRayColor * rim* _SelfBritness ;
} ENDCG
} Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag #include "Lighting.cginc" sampler2D _MainTex;
float4 _MainTex_ST; struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD1;
}; v2f vert(appdata_base v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
return o;
} fixed4 frag(v2f i) : SV_Target
{
return tex2D(_MainTex, i.uv);
} ENDCG
}
} FallBack "Diffuse"
}