init

Assets/Materials/Bullet/CircleShadow_Shader.shader

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+Shader "Unlit/CircleShadow_Shader"
+{
+    Properties
+    {
+		[HDR]
+		_Color("Color", Color)=(0, 0, 0, 1)
+		_Density("Density", Range(0, 1))=1
+		_Rad("Radius", Float)=1
+    }
+    SubShader
+    {
+        Tags { "RenderType"="Transparent" "Queue"="Transparent" }
+		Blend SrcAlpha OneMinusSrcAlpha
+        LOD 100
+
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+            // make fog work
+            #pragma multi_compile_fog
+
+            #include "UnityCG.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float2 uv : TEXCOORD0;
+            };
+
+            struct v2f
+            {
+                float2 uv : TEXCOORD0;
+                UNITY_FOG_COORDS(1)
+                float4 vertex : SV_POSITION;
+            };
+
+			float4 _Color;
+			float _Density;
+			float _Rad;
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+				o.uv = v.uv;
+                UNITY_TRANSFER_FOG(o,o.vertex);
+                return o;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+				_Density /= 2;
+
+				float2 centeredUV = i.uv - 0.5f;
+				float radialMask = 1-smoothstep(_Density, 1-_Density, 1/_Rad*length(centeredUV));
+
+                return fixed4(_Color.rgb, radialMask*_Color.a);
+            }
+            ENDCG
+        }
+    }
+}