Heat maps

Heatmaps in Unity 5.4+

Step1：The shader

Shader "Example/Heatmap" {
    Properties {
        _HeatTex ("Texture", 2D) = "white" {}
    }
    SubShader {
        Tags {"Queue"="Transparent"}
        Blend SrcAlpha OneMinusSrcAlpha // Alpha blend

        Pass {
            CGPROGRAM
            #pragma vertex vert             
            #pragma fragment frag

            struct vertInput {
                float4 pos : POSITION;
            };  

            struct vertOutput {
                float4 pos : POSITION;
                fixed3 worldPos : TEXCOORD1;
            };

            vertOutput vert(vertInput input) {
                vertOutput o;
                o.pos = mul(UNITY_MATRIX_MVP, input.pos);
                o.worldPos = mul(_Object2World, input.pos).xyz;
                return o;
            }

            uniform int _Points_Length = 0;     //Array Length
            uniform float3 _Points [20];        // (x, y, z) = position
            uniform float2 _Properties [20];    // x = radius, y = intensity

            sampler2D _HeatTex;

            half4 frag(vertOutput output) : COLOR {
                // Loops over all the points
                half h = 0;
                for (int i = 0; i < _Points_Length; i ++)
                {
                    // Calculates the contribution of each point
                    half di = distance(output.worldPos, _Points[i].xyz);

                    half ri = _Properties[i].x;
                    half hi = 1 - saturate(di / ri);

                    h += hi * _Properties[i].y;
                }

                // Converts (0-1) according to the heat texture
                h = saturate(h);
                half4 color = tex2D(_HeatTex, fixed2(h, 0.5));
                return color;
            }
            ENDCG
        }
    } 
    Fallback "Diffuse"
}

Setp2: The C# code

using UnityEngine;
using System.Collections;

public class Heatmap1 : MonoBehaviour
{
    public Vector4[] positions;
    public Vector4[] properties;

    public Material material;

    public int count = 50;

    void Start ()
    {
        positions = new Vector4[count];
        properties = new Vector4[count];

        for (int i = 0; i < positions.Length; i++)
        {
            positions[i] = new Vector4(Random.Range(-0.4f, +0.4f), Random.Range(-0.4f, +0.4f), 0, 0);
            properties[i] = new Vector4(Random.Range(0f, 0.25f), Random.Range(-0.25f, 1f), 0, 0);
        }
    }

    void Update()
    {
        //
        for (int i = 0; i < positions.Length; i++)
            positions[i] += new Vector4(Random.Range(-0.1f,+0.1f), Random.Range(-0.1f, +0.1f), 0, 0) * Time.deltaTime;

        //[Propagates value to the shader](https://docs.unity3d.com/ScriptReference/Material.SetVectorArray.html)
        material.SetInt("_Points_Length", count);
        material.SetVectorArray("_Points", positions);
        material.SetVectorArray("_Properties", properties);
    }
}

Setp3: The Assets

The “_HeatTex” you can use like the following texture: