Creating a Circle around the terrain

Basic

Example

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Shader "Custom/Test" {

    Properties {
	    _Center("Center", Vector) = (0,0,0,0)
	    _Radius("Radius", Float) = 0.5
	    _RadiusColor("Radius Color", Color) = (1,0,0,1)
	    _RadiusWidth("Radius Width", Float) = 2
	    _MainTex("_MainTex",2D)  =  "white" {}
    }

    SubShader {
		Tags { "RenderType"="Opaque" }

		CGPROGRAM
		#pragma surface surf Standard
        
		float3 _Center;
	    float _Radius;
	    fixed4 _RadiusColor;
	    float _RadiusWidth;
	    sampler2D _MainTex;

		struct Input
	    {
	      float2 uv_MainTex; // The UV of the terrain texture
	      float3 worldPos;   // The in-world position
	    };

		void surf(Input IN, inout SurfaceOutputStandard o)
	    {
	      float4 co = tex2D(_MainTex, IN.uv_MainTex);
	      float d = distance(_Center, IN.worldPos);
	      
	      if (d > _Radius && d < _Radius + _RadiusWidth)
	        o.Albedo = lerp(_RadiusColor,co.rgb,1-_RadiusColor.a) ;
	      else
	        o.Albedo = co.rgb;
	    }
        ENDCG
    }
}

WARNING

distance calculator

利用distance函数计算与世界坐标的位置关系，从而画出⭕️ ，可以通过_RadiusColor的alpha值控制⭕️的透明度。

致歉

hexo代码格式紊乱导 ，正在寻找为什么会乱？知道的请留言说下 😄