1 创建一个相机，把depth.cs和RenderTexture.cs挂在相机上

2 depth.cs代码

using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;

public class Depth : MonoBehaviour
{
    // Start is called before the first frame update
    private Camera m_Camera;
    public RenderTexture depthTexture, source;
    public Material Mat;
    private int width = CameraTexture.width;
    private int height = CameraTexture.height;
    private static int index =0;
    void Start()
    {
         
        m_Camera = gameObject.GetComponent<Camera>();
   
        // 手动设置相机，让它提供场景的深度信息
        // 这样我们就可以在shader中访问_CameraDepthTexture来获取保存的场景的深度信息
        // float depth = UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, uv)); 获取某个像素的深度值
        m_Camera.depthTextureMode = DepthTextureMode.Depth;
        depthTexture = new RenderTexture(width, height, 32,RenderTextureFormat.ARGBFloat);
        
    }

    private bool test = true;
    void OnPostRender()
    {
        source = m_Camera.activeTexture;
        Graphics.Blit(source, depthTexture, Mat);
        
        //save();
        //if (test)
        //{
        //    save();
        //    test = false;
        //}

    }

    public void save()
    {
        //if (this.name == "RenderAllCamera")
        //{
        //    saveDepthMap(source, "scene.jpg");
        //}
        saveDepthMap(source, "imgs/" + this.name + index + "_scene.jpg");
        //saveDepthMap(depthTexture, "imgs/" + this.name + index + ".jpg");
        index++;
        Debug.Log(index);
    }


    // Event function that Unity calls after a Camera has finished rendering, that allows you to modify the Camera's final image.
    /*
    void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        if (null != Mat)
        {
            // Copies source texture into destination render texture with a shader.
            // 使用material把这个source渲染到那个destination, Blit(source, destination, material)
            // 使用这个material的意思是使用这个material的shader
            // 这个material没必要赋到物体上
            // Graphics.Blit(source, destination, Mat);
            RenderTexture depthTexture = new RenderTexture(source.width, source.height, 32);
            Graphics.Blit(source, depthTexture, Mat);
            saveDepthMap(depthTexture);
        }
    }
    */

    private void saveDepthMap(RenderTexture DepthRenderTexture, string MapName)
    {
        int Width = DepthRenderTexture.width;
        int Height = DepthRenderTexture.height;
        Texture2D texture2D = new Texture2D(Width, Height);
        var previous = RenderTexture.active;
        RenderTexture.active = DepthRenderTexture;
        texture2D.ReadPixels(new Rect(0, 0, Width, Height), 0, 0);
        RenderTexture.active = previous;
        texture2D.Apply();
        byte[] Data = texture2D.EncodeToPNG();
        FileStream file = File.Open(MapName, FileMode.Create, FileAccess.Write);
        BinaryWriter writer = new BinaryWriter(file);
        writer.Write(Data);
        file.Close();
    }
    
}

3 RenderTexture.cs代码

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
 

public class CameraTexture : MonoBehaviour
{
    // Start is called before the first frame update

    public RenderTexture renderTexture;
    public  static  int width = 32;
    public  static  int height = 26;
   
    void Start()
    {
        renderTexture = new RenderTexture(width, height, 32, RenderTextureFormat.ARGBFloat);
        GetComponent<Camera>().targetTexture = renderTexture;

    }

    // Update is called once per frame
    void Update()
    {
       
    }
}

4 DepthMaterial

1 创建材质球

2 替换为depth shader

depth.shader

Shader "Custom/Depth" 
{  
	SubShader {  
		
		Pass{  
			CGPROGRAM  
			#pragma vertex vert  
			#pragma fragment frag  
			#include "UnityCG.cginc"  
 
			sampler2D _CameraDepthTexture;  
			struct v2f 
			{  
			   float4 pos : SV_POSITION;  
			   float4 scrPos:TEXCOORD1;  
			};  
 
			v2f vert (appdata_base v)
			{  
			   v2f f;  		  
			   f.pos = UnityObjectToClipPos (v.vertex);  
			   f.scrPos=ComputeScreenPos(f.pos);  
			   return f;  
			}  
			  
			half4 frag (v2f f) : COLOR
			{  
			   float depthValue =Linear01Depth (tex2Dproj(_CameraDepthTexture,UNITY_PROJ_COORD(f.scrPos)).r);
			   return half4(depthValue*10,depthValue*10,depthValue*10,1);  
			}  
			ENDCG  
		}  
	}  
	FallBack "Diffuse"  
} 

5 如下