简易3D热力图

Shader "Custom/HeightMapCreator"
{
    Properties
    {
        _MainTex("Texture", 2D) = "black"{}
        _Shape ("Shape", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" }
        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;
                float2 st : TEXCOORD1;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            sampler2D _Shape;
            float4 _Shape_ST;
            
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                o.st = TRANSFORM_TEX(v.uv, _Shape);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = tex2D(_MainTex, i.uv);
                col = (col + tex2D(_Shape, i.st));
                return col;
            }
            ENDCG
        }
    }
}

    public class PointInfo
    {
        public Vector3 worldPos;
        public float value;

        public static implicit operator Vector3(PointInfo info)
        {
            return info.worldPos;
        }
    }
    public class HeightMapInfo
    {
        public Matrix4x4 worldToLocalMatrix;
        public int worldSize_x;      // total
        public int worldSize_z;      // total

        public int heightMapSize_x;
        public int heightMapSize_z;
        public Vector2 worldToMapScale { get { return new Vector2((float)heightMapSize_x / (float)worldSize_x, (float)heightMapSize_z / (float)worldSize_z); } }

        public Texture2D renderShape;
        public int renderSize_x;
        public int renderSize_y;
        public Vector2 renderShapeScale { get { return new Vector2((float)heightMapSize_x / (float)renderSize_x, (float)heightMapSize_z / (float)renderSize_y); } }
    }

    private static RenderTexture Blit(RenderTexture mainTexture, Material material, HeightMapInfo info, Vector3 worldPos)
    {
        var region = new Rect(-info.worldSize_x * 0.5f, -info.worldSize_z * 0.5f, info.worldSize_x, info.worldSize_z);
        var localPos = info.worldToLocalMatrix.MultiplyPoint3x4(worldPos);  // based on middle-center
        var localPos_xz = new Vector2(localPos.x, localPos.z);
        var renderTarget = RenderTexture.GetTemporary(info.heightMapSize_x, info.heightMapSize_z, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Default);

        var offset = localPos_xz - region.min;
        var offset_u = (offset.x / region.width) * -1.0f;
        var offset_v = (offset.y / region.height) * -1.0f;

        var shapeRenderOffset_u = info.renderSize_x * 0.5f / info.heightMapSize_x;
        var shapeRenderOffset_v = info.renderSize_y * 0.5f / info.heightMapSize_z;

        var final_u = offset_u + shapeRenderOffset_u;
        var final_v = offset_v + shapeRenderOffset_v;
        var final_uv = new Vector2(final_u, final_v);

        // offset is scaled
        var final_uv_scaled = Vector2.Scale(final_uv, info.renderShapeScale);
        material.SetTextureOffset("_Shape", final_uv_scaled);

        Graphics.Blit(mainTexture, renderTarget, material);
        RenderTexture.ReleaseTemporary(mainTexture);

        return renderTarget;
    }