如何在Unity3D中编写支持百万数据点的热图着色器

Shader "Custom/HeatmapShader"
{
    Properties
    {
        _MainTex ("Data Texture", 2D) = "white" {}
        _ColorMap ("Color Map", 2D) = "white" {}
        _MinValue ("Min Value", Float) = 0.0
        _MaxValue ("Max Value", Float) = 1.0
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            sampler2D _ColorMap;
            float _MinValue;
            float _MaxValue;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                float dataValue = tex2D(_MainTex, i.uv).r;
                float normalizedValue = saturate((dataValue - _MinValue) / (_MaxValue - _MinValue));
                fixed4 color = tex2D(_ColorMap, float2(normalizedValue, 0.5));
                return color;
            }
            ENDCG
        }
    }
    FallBack "Diffuse"
}