今天项目中有个需求是，当奖牌没有获得的时候，变灰色，这个灰色不单单是改变原图片的颜色就行了，而是需要特定的shader进行颜色叠加才能实现。（很多游戏技能变灰应该也是这样做的）
当弄好shader做好材质之后，当需要变灰时执行下面方法
void SetGray()
{
Icon.color = Color.gray;
Icon.material = Material_Gray; //假设Material_Gray为变灰的材质球
}
这样设置之后，当代码一运行，所有ui界面全变灰了，并且就算重启运行项目，还是灰的，吓得我以为要把全部ui重新改一遍。
研究后发现相同材质的Image在创建后引用的是内存中同一份材质，所以改掉一个后，其实就是改掉了所有Image的默认材质，这个时候如果需要单独修改这个Image的材质，如使某些技能灰掉，那么就在创建实例时新建一份材质，之后修改这一份材质，导致的问题是这样内存中就会有多份材质存在，慎用。如下：
void SetGray()
{
Icon.color = Color.gray;
if (Material_Gray != null)
{
Material material = new Material(Material_Gray);
Icon.material = material;
}
}
下面是是使图片置灰的shader，其中有不少无用参数，将所有参数设置为0就好了：
// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
Shader "UI/Default_Overlay"
{
Properties
{
[PerRendererData] _MainTex ("Sprite Texture", 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
{
Name "Default"
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0
#include "UnityCG.cginc"
#include "UnityUI.cginc"
#pragma multi_compile __ UNITY_UI_ALPHACLIP
struct appdata_t
{
float4 vertex : POSITION;
float4 color : COLOR;
float2 texcoord : TEXCOORD0;
UNITY_VERTEX_INPUT_INSTANCE_ID
};
struct v2f
{
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
float4 worldPosition : TEXCOORD1;
UNITY_VERTEX_OUTPUT_STEREO
};
fixed4 _Color;
fixed4 _TextureSampleAdd;
float4 _ClipRect;
v2f vert(appdata_t IN)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(IN);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
OUT.worldPosition = IN.vertex;
OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
OUT.texcoord = IN.texcoord;
OUT.color = IN.color * _Color;
return OUT;
}
sampler2D _MainTex;
fixed4 frag(v2f IN) : SV_Target
{
fixed4 tex = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;//tex2D(_MainTex, IN.uv);
float gray = dot(tex.rgb, float3(0.299, 0.587, 0.114));
// 输出灰色
return fixed4(gray, gray, gray, tex.a);
}
ENDCG
}
}
}
============ ================= ===== ===== 手动分割================== ======== ======= ===========
下面是另外一种置灰的shade，可以进行灰色彩色切换 ：（参考文章传送门）
Shader "Custom/GrayScaleShader"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {
}
_IsGrayScale ("Is GrayScale", Range(0, 1)) = 0
}
SubShader
{
Tags {
"Queue"="Transparent" "RenderType"="Transparent"}
LOD 100
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
};
sampler2D _MainTex;
bool _IsGrayScale;
v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = v.uv;
return o;
}
fixed4 frag (v2f i) : SV_Target
{
fixed4 tex = tex2D(_MainTex, i.uv);
// 判断是否是灰度效果
if (_IsGrayScale)
{
// 转换为灰度
float gray = dot(tex.rgb, float3(0.299, 0.587, 0.114));
// 输出灰色
return fixed4(gray, gray, gray, tex.a);
}
else
{
// 输出彩色
return tex;
}
}
ENDCG
}
}
}
该shader的置灰使用方法：
grayScaleMaterial.SetInt("_IsGrayScale", isGrayScale ? 1 : 0);
over~