这个应该是挺常见的，或许你会说，美术直接帮你裁成圆的不就可以吗。有时候可以，有时候不行。什么时候不行呢？当你在游戏中有些地方使用方形的，有些地方使用圆形的。这时候就不能让美术帮你裁了。不然不就有两份资源了。
本文读者最好已经知道怎么使用NGUI创建图集，使用它的UISprite和UITexture。
插件：NGUI 3.5.7
作为一个学习过两天Shader的人，我觉得，这应该难不倒我。因此，我立马在U3D的Project面板中噼里啪啦一阵狂搞。创建一个Shader。
Shader "Unlit/Transparent Colored Mask"
{
Properties
{
_MainTex ("Base (RGB), Alpha (A)", 2D) = "black" {}
_Mask ("Mask Alpha (A)", 2D) = "white" {}
}
SubShader
{
LOD 100
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
Cull Off
Lighting Off
ZWrite Off
Fog { Mode Off }
Offset -1, -1
Blend SrcAlpha OneMinusSrcAlpha
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata_t
{
float4 vertex : POSITION;
float2 texcoord : TEXCOORD0;
fixed4 color : COLOR;
};
struct v2f
{
float4 vertex : SV_POSITION;
half2 texcoord : TEXCOORD0;
fixed4 color : COLOR;
fixed gray : TEXCOORD1;
};
sampler2D _MainTex;
sampler2D _Mask;
float4 _MainTex_ST;
float4 _Mask_ST;
v2f vert (appdata_t v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.texcoord = v.texcoord;
o.color = v.color;
o.gray = dot(v.color, fixed4(1,1,1,0));
return o;
}
fixed4 frag (v2f i) : COLOR
{
fixed4 col;
col = tex2D(_MainTex, i.texcoord) * i.color;
col.a = col.a * tex2D(_Mask, i.texcoord).a;
return col;
}
ENDCG
}
}
SubShader
{
LOD 100
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
Pass
{
Cull Off
Lighting Off
ZWrite Off
Fog { Mode Off }
Offset -1, -1
ColorMask RGB
AlphaTest Greater .01
Blend SrcAlpha OneMinusSrcAlpha
ColorMaterial AmbientAndDiffuse
SetTexture [_MainTex]
{
Combine Texture * Primary
}
}
}
}主要实现裁剪的代码为：fixed4 frag (v2f i) : COLOR
{
fixed4 col;
col = tex2D(_MainTex, i.texcoord) * i.color;
col.a = col.a * tex2D(_Mask, i.texcoord).a;
return col;
}相信大家很容易就看懂了，这里是把Mask贴图的Alpha通道的值和原图片的进行相乘。新建一个UItexture。
这个Mask图片为
然后修改这个图集的材质使用我们的Shader。
额。。。效果咋成下面这样啦。。。不太对的赶脚
Shader "Unlit/Transparent Colored Mask"
{
Properties
{
_MainTex ("Base (RGB), Alpha (A)", 2D) = "black" {}
_Mask ("Mask Alpha (A)", 2D) = "white" {}
_WidthRate ("Sprite.width/Atlas.width", float) = 1
_HeightRate ("Sprite.height/Atlas.height", float) = 1
_XOffset("offsetX", float) = 0
_XOffset("offsetY", float) = 0
}
SubShader
{
LOD 100
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
Cull Off
Lighting Off
ZWrite Off
Fog { Mode Off }
Offset -1, -1
Blend SrcAlpha OneMinusSrcAlpha
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata_t
{
float4 vertex : POSITION;
float2 texcoord : TEXCOORD0;
fixed4 color : COLOR;
};
struct v2f
{
float4 vertex : SV_POSITION;
half2 texcoord : TEXCOORD0;
fixed4 color : COLOR;
fixed gray : TEXCOORD1;
};
sampler2D _MainTex;
sampler2D _Mask;
float4 _MainTex_ST;
float4 _Mask_ST;
float _WidthRate;
float _HeightRate;
float _XOffset;
float _YOffset;
v2f vert (appdata_t v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.texcoord = v.texcoord;
o.color = v.color;
o.gray = dot(v.color, fixed4(1,1,1,0));
return o;
}
fixed4 frag (v2f i) : COLOR
{
fixed4 col;
col = tex2D(_MainTex, i.texcoord) * i.color;
col.a = col.a * tex2D(_Mask, float2((i.texcoord.x-_XOffset)/_WidthRate, (i.texcoord.y-(1-_YOffset))/_HeightRate)).a;
return col;
}
ENDCG
}
}
SubShader
{
LOD 100
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
Pass
{
Cull Off
Lighting Off
ZWrite Off
Fog { Mode Off }
Offset -1, -1
ColorMask RGB
AlphaTest Greater .01
Blend SrcAlpha OneMinusSrcAlpha
ColorMaterial AmbientAndDiffuse
SetTexture [_MainTex]
{
Combine Texture * Primary
}
}
}
}using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
public class ScaleTexcoord : MonoBehaviour
{
private float wr;
private float hr;
private float offX;
private float offY;
private UISprite s;
void Awake()
{
s = GetComponent<UISprite>();
wr = s.GetAtlasSprite().width * 1.0f / s.atlas.spriteMaterial.mainTexture.width;
offX = s.GetAtlasSprite().x * 1.0f / s.atlas.spriteMaterial.mainTexture.width;
hr = s.GetAtlasSprite().height * 1.0f / s.atlas.spriteMaterial.mainTexture.height;
offY = (s.GetAtlasSprite().y + s.GetAtlasSprite().height) * 1.0f / s.atlas.spriteMaterial.mainTexture.height;
}
public void Update()
{
s.atlas.spriteMaterial.SetFloat("_WidthRate", wr);
s.atlas.spriteMaterial.SetFloat("_HeightRate", hr);
s.atlas.spriteMaterial.SetFloat("_XOffset", offX);
s.atlas.spriteMaterial.SetFloat("_YOffset", offY);
}
}
[Shader]对NGUI的UISprite和UITexture进行裁剪
原文地址：http://blog.csdn.net/kakashi8841/article/details/44851885
