上个月写了一篇使用像素shader返回累加信息的Trick:

后来无意中发现DX11/Compute shader有一类数据格式更适合这类操作。

 

c sharp脚本：

using System.Collections;using System.Collections.Generic;using UnityEngine;public class ComputeShaderTest : MonoBehaviour{    public ComputeShader computeShader;    void Awake()    {        //reference: https://answers.unity.com/questions/1035132/how-can-i-read-in-the-actual-elements-from-an-appe.html        var kernelID = computeShader.FindKernel("CSMain");        var appendBuffer = new ComputeBuffer(64, sizeof(int), ComputeBufferType.Append);        appendBuffer.SetCounterValue(0);        //定义了缓冲区长度为64*结构大小的appendBuffer.        var consumeBuffer = new ComputeBuffer(64, sizeof(int), ComputeBufferType.Append);        consumeBuffer.SetCounterValue(0);        consumeBuffer.SetData(new int[] { 97, 98, 99 });        consumeBuffer.SetCounterValue(3);        //consume类型结构相当于栈，所以取到的第一个值是99。        computeShader.SetBuffer(kernelID, "appendBuffer", appendBuffer);        computeShader.SetBuffer(kernelID, "consumeBuffer", consumeBuffer);        computeShader.Dispatch(kernelID, 1, 1, 1);        //单个线程组的大小为8，定义了1个线程组。也就是说会返回8个数据。        var countBuffer = new ComputeBuffer(1, sizeof(int), ComputeBufferType.IndirectArguments);        ComputeBuffer.CopyCount(appendBuffer, countBuffer, 0);        //通过这个方法拿到第一个数据。        int[] counter = new int[1] { 0 };        countBuffer.GetData(counter);        int count = counter[0];        Debug.Log("count: " + count);        var data = new int[count];        appendBuffer.GetData(data);        Debug.Log("data length: " + data.Length);        for (int i = 0; i < data.Length; i++)        {            Debug.Log(data[i]);        }        consumeBuffer.Release();        consumeBuffer.Dispose();        appendBuffer.Release();        appendBuffer.Dispose();        countBuffer.Release();        countBuffer.Dispose();    }}

 

 

compute shader:

#pragma kernel CSMainAppendStructuredBuffer
     
       appendBuffer;ConsumeStructuredBuffer
      
        consumeBuffer;[numthreads(8,1,1)]void CSMain (uint3 id : SV_DispatchThreadID){    if (id.x == 2)    {        int value = consumeBuffer.Consume();        appendBuffer.Append(value);    }    if (id.x > 2)    {        appendBuffer.Append(id.x);    }}
      
     

 

 

传入的线程组是8,1,1。并且Dispatch只运行了一个线程组，所以每一次传入id的x值依次为0,1,2,3,4,5,6,7

在id是2的时候读consume里的值，所以第一个是99.

最终输出:99,3,4,5,6,7。