NGUI图片变灰通用

新增一个 UI_CG.cginc文件

#ifndef UI_CG
#define UI_CG
inline half4 GreyUI(sampler2D _MainTex,sampler2D _AlphaTex,half2 texUV,half4 vColor)
{
	half4 alphaColor = tex2D(_AlphaTex,texUV);
	half4 mainColor = tex2D(_MainTex, texUV);
	mainColor.a *= alphaColor.r;

    float t1 = step(0.001,vColor.r - 0.49);
    float t2 = step(0.001,0.51 - vColor.r);
	half tmp = t1 * t2;
    //half tmp = step(0.001,vColor.r - 0.49) * step(0.001,0.51 - vColor.r);
	half grey = dot(mainColor.rgb, half3(0.299, 0.587, 0.114));
	mainColor = tmp * half4(grey,grey,grey,mainColor.a) + (1 - tmp) * mainColor * vColor;
	return mainColor;
}
#endif

修改图片的shader
Transparent Colored
修改textrue的shader
Unlit/Transparent Colored

half4 frag (v2f IN) : COLOR
{
	return GreyUI(_MainTex,_AlphaTex,IN.texcoord,IN.color);
	// return tex2D(_MainTex, IN.texcoord) * IN.color;
}