示例

Shader "Custom/Gradient"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Color("Color", Color) = (1,1,1,1)
        _Diameter ("Diameter", Range(0.0, 10.0)) = 2.0
    }
    SubShader
    {
        Tags { "Queue" = "Transparent" "RenderType" = "Transparent" }
        LOD 100

        Pass
        {
            Blend SrcAlpha OneMinusSrcAlpha
		
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"
			
            uniform fixed4 _Color;
            uniform float _Diameter;
            uniform float _DistanceInMeters;

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float4 uva : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                float scale = lerp(_Diameter, 0, v.vertex.y);
				
                o.vertex = UnityObjectToClipPos(v.vertex);
                fixed2 uv = TRANSFORM_TEX(v.uv, _MainTex);
                o.uva = float4(uv.x, uv.y, 0, scale);
				
                UNITY_TRANSFER_FOG(o,o.vertex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uva.xy);
                col *= _Color;
                col.a = i.uva.a;
                return col;
            }
            ENDCG
        }
    }
}

效果（渐变的胶囊体）