【每日一记】unity3d 图片置灰shader

项目须要。參考了一下网上的资料，写了一个shader，给button置灰。

shader详细实现例如以下：

2016.07.25补充，支持mask剪裁

Shader "Transparent Colored Gray"
{
Properties
{
_MainTex ("Base (RGB), Alpha (A)", 2D) = "white" {}
_Color ("Tint", Color) = (1,1,1,1)

_StencilComp ("Stencil Comparison", Float) = 8
_Stencil ("Stencil ID", Float) = 0
_StencilOp ("Stencil Operation", Float) = 0
_StencilWriteMask ("Stencil Write Mask", Float) = 255
_StencilReadMask ("Stencil Read Mask", Float) = 255

_ColorMask ("Color Mask", Float) = 15

[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
}

SubShader
{
Tags
{
"Queue"="Transparent"
"IgnoreProjector"="True"
"RenderType"="Transparent"
"PreviewType"="Plane"
"CanUseSpriteAtlas"="True"
}

Stencil
{
Ref [_Stencil]
Comp [_StencilComp]
Pass [_StencilOp]
ReadMask [_StencilReadMask]
WriteMask [_StencilWriteMask]
}

Cull Off
Lighting Off
ZWrite Off
ZTest [unity_GUIZTestMode]
Blend SrcAlpha OneMinusSrcAlpha
ColorMask [_ColorMask]

Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag

#include "UnityCG.cginc"
#include "UnityUI.cginc"

#pragma multi_compile __ UNITY_UI_ALPHACLIP

struct appdata_t
{
float4 vertex : POSITION;
float4 color : COLOR;
float2 texcoord : TEXCOORD0;
};

struct v2f
{
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
half2 texcoord : TEXCOORD0;
float4 worldPosition : TEXCOORD1;
};

fixed4 _Color;
fixed4 _TextureSampleAdd;
float4 _ClipRect;

v2f vert(appdata_t IN)
{
v2f OUT;
OUT.worldPosition = IN.vertex;
OUT.vertex = mul(UNITY_MATRIX_MVP, OUT.worldPosition);

OUT.texcoord = IN.texcoord;

#ifdef UNITY_HALF_TEXEL_OFFSET
OUT.vertex.xy += (_ScreenParams.zw-1.0)*float2(-1,1);
#endif

OUT.color = IN.color * _Color;
return OUT;
}

sampler2D _MainTex;

fixed4 frag(v2f IN) : SV_Target
{
// Sample the texture
half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
float c = 0.299*color.r + 0.587*color.g + 0.184*color.b;
color.r = color.g = color.b = c;
color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#ifdef UNITY_UI_ALPHACLIP
clip (color.a - 0.001);
#endif

return color;
}
ENDCG
}
}
}

先建一个名为colorGrayMat的材质，把shader文件附加到材质上。

管理material材质代码：

public class MaterialManager
{
    public static void addMaterial(Image img, string materialName)
    {
        Material material = GameAssets.instance.loadMaterial(materialName);
        if (img != null && material != null)
        {
            img.material = material;
        }
    }

    public static void addGrayMaterial(Image img)
    {
        addMaterial(img,"colorGrayMat");
    }
}

调用代码：

MaterialManager.addGrayMaterial(img);

关于shader资料：

官网资料： http://docs.unity3d.com/Manual/SL-SurfaceShaders.html（英文）

http://unity3d.9tech.cn/news/2013/1220/39315.html（中文）

猫都能学会的Unity3D Shader入门指南 http://www.onevcat.com/2013/07/shader-tutorial-1/