<1>新建材质球和shader，shader请在官方下载内置shader(UI)
效果：
思路：
裁剪成圆，那就剔除大于圆半径的像素，很鸡儿简单
代码：
定义圆形半径 _Radius("半径",Range(0-0.5))=0.5
frag片元处理
float2 nor = float2(0.5,0.5)-uv;//圆心在0.5,0.5
if(length(nor)>_Radius)//计算圆心到UV坐标的距离 大于半径剔除
col.a = 0;
clip(col.a-0.01);//剔除alpha小于0
源码:
// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
Shader "Tang/imgCut"
{
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
//my member
_Radius("圆半径",Range(0,0.5)) = 0.3
[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
#define PI 3.1415926
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;
float _Radius;
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
{
float2 uv = IN.texcoord.xy;
float4 col = IN.color;
float2 nor =float2(0.5,0.5)-uv;
if (length(nor)>_Radius)
col.a = 0;
clip(col.w-0.01);
half4 color = (tex2D(_MainTex,uv) + _TextureSampleAdd) * col;
color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#ifdef UNITY_UI_ALPHACLIP
clip(color.a - 0.001);
#endif
return color;
}
ENDCG
}
}
}