Unity3d实现红外热成像效果

1.将需要在红外图像中高亮的物体设置到图层PostProcessing。

2.新建一个相机CameraHighLight，设置其Culling Mask为PostProcessing，也就是在这个相机中只有PostProcessing图层的物体可见。

3.新建一个RenderTexture，命名为HightLightRt，将CameraHighLight的Target Texture设HightLightRt。

4.新建一个相机Camera2，这个相机用于显示其他物体。

接下来将CameraHighLight和Camera2中画面转化为两张灰度图，再合并成一张图。合并的过程使用OnRenderImage函数，该函数中使用shader的片断着色器处理，取到两张图相同位置的像素后，谁的灰度值高就取谁的亮度。为了高度CameraHighLight的物体，取Camera2中像素时将适当缩小亮度值。

5.新建C#脚本ThermalVision.cs，将ThermalVision.cs挂载到Camera2。

using UnityEngine;

public class ThermalVision : MonoBehaviour
{
    public bool IsInverse = false;

    public RenderTexture OtherTex;
    private Material material1;
    private Material material2;
    // Creates a private material used to the effect
    void Awake()
    {
        material1 = new Material(Shader.Find("Hidden/Thermal1"));
        material2 = new Material(Shader.Find("Hidden/Thermal2"));
    }

    // Postprocess the image
    void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        if (IsInverse)
        {
            material1.SetTexture("_OtherTex", OtherTex);

            Graphics.Blit(source, destination, material1);
        }
        else
        {
            material2.SetTexture("_OtherTex", OtherTex);

            Graphics.Blit(source, destination, material2);
        }
    }
}

6.新建两个shader，分别为Thermal1、Thermal2，一个为白色模式，一个为黑色模式。

Shader "Hidden/Thermal1" {
	Properties{
		_MainTex("Base (RGB)", 2D) = "white" {}
		_OtherTex("Other (RGB)", 2D) = "white" {}
	}
		SubShader{
			Pass {
				CGPROGRAM
				#pragma vertex vert_img
				#pragma fragment frag
				#include "UnityCG.cginc"
				uniform sampler2D _MainTex;
				uniform sampler2D _OtherTex;
				float4 frag(v2f_img i) : COLOR {
					fixed4 renderTex = tex2D(_MainTex, i.uv);
					fixed4 OtherTex = tex2D(_OtherTex, i.uv);

					fixed gray1 = 0.2125 * renderTex.r + 0.7154 * renderTex.g + renderTex.b;
					fixed gray2 = 0.2125 * OtherTex.r + 0.7154 * OtherTex.g + OtherTex.b;

					fixed maxgr = gray1 * 0.1* step(gray2, gray1) + gray2 * step(gray1, gray2);
					//fixed maxgr = max(gray1, gray2);
					fixed3 grayColor = float3(maxgr, maxgr, maxgr);

					float4 result = renderTex;
					result.rgb = grayColor;
					return result;

				}
				ENDCG
			}
		}
}

Shader "Hidden/Thermal2" {
	Properties{
		_MainTex("Base (RGB)", 2D) = "white" {}
		_OtherTex("Other (RGB)", 2D) = "white" {}
	}
		SubShader{
			Pass {
				CGPROGRAM
				#pragma vertex vert_img
				#pragma fragment frag
				#include "UnityCG.cginc"
				uniform sampler2D _MainTex;
				uniform sampler2D _OtherTex;
				float4 frag(v2f_img i) : COLOR {		
					fixed4 renderTex = tex2D(_MainTex, i.uv);
					fixed4 OtherTex = tex2D(_OtherTex, i.uv);

					fixed gray1 = 0.2125 * renderTex.r + 0.7154 * renderTex.g + renderTex.b;
					fixed gray2 = 0.2125 * OtherTex.r + 0.7154 * OtherTex.g + OtherTex.b;

					fixed maxgr = gray1 * 0.5* step(gray2, gray1) + gray2 * step(gray1, gray2);
					fixed3 grayColor = float3(maxgr, maxgr, maxgr);
					float4 result = renderTex;
					result.rgb = float3(1- grayColor.r, 1 - grayColor.g, 1 - grayColor.b);
					return result;

				}
				ENDCG
			}
		}
}

最终效果