為什麼要用計算著色器呢？ 因為人臉表情基模型頂點數實在是太多了，而且有不止一個模型，動畫越精細，表情基模型越多，這個時候僅僅用CPU計算顯然是不夠的，所以就開始上GPU了，平行計算。

直接上計算著色器的程式碼:

1、ComputeShader.compute

#pragma kernel Cul 

RWStructuredBuffer<float3> vertBuffer;
StructuredBuffer<float3> blendshapeBuffer;
StructuredBuffer<float3> naturalBuffer;
float weight;
 
//表情基權重

[numthreads(32,32,1)]
void Cul(uint3 id : SV_DispatchThreadID) {
	int index = id.x * 32 * 4 + id.y;
	vertBuffer[index] = vertBuffer[index] + (blendshapeBuffer[index] - naturalBuffer[index]) * weight;
}

2、ComputeShaderCS.cs

[RequireComponent(typeof(MeshFilter))]
public class ComputeShaderCS :
 
 MonoBehaviour {
    //表情基的Mesh網格 0為natural模型
    public Mesh[] meshs;
    //每個表情基的權重值陣列(限制在0-1)
    [Range(0,1)]
    public float[] weights;
    //計算著色器
    public ComputeShader shader;

    ComputeBuffer vertBuffer;       //頂點緩衝
    ComputeBuffer blendshapeBuffer; //表情基模型緩衝
    ComputeBuffer naturalBuffer;    //natural模型緩衝
 


    //模型網格資訊
    Mesh mesh;

    private void Start() {
        //獲取模型的網格資訊
        mesh = GetComponent<MeshFilter>().mesh;

        //分配緩衝空間(每個float佔4個位元組，一個Vector3包括3個float,所佔大小為4*3)
        vertBuffer = new ComputeBuffer(meshs[0].vertices.Length, 4 * 3);
        blendshapeBuffer = new ComputeBuffer(meshs[0].vertices.Length, 4 * 3);
        naturalBuffer = new ComputeBuffer(meshs[0].vertices.Length, 4 * 3);
    }

    private void Update() {
        //不必每一幀執行，此處為便於測試
        RunShader();
    }

    //執行計算著色器
    void RunShader() {

        int kernel = shader.FindKernel("Cul");

        Vector3[] vertices = new Vector3[meshs[0].vertices.Length];

        //初始化緩衝
        vertBuffer.SetData(meshs[0].vertices);
        naturalBuffer.SetData(meshs[0].vertices);

        //填充緩衝
        shader.SetBuffer(kernel, "vertBuffer", vertBuffer);
        shader.SetBuffer(kernel, "naturalBuffer", naturalBuffer);

        //根據權重值與表情基計算新的頂點位置
        for (int w = 1; w < weights.Length; w++) {

            if (weights[w] <= 0) continue;

            //初始化緩衝
            blendshapeBuffer.SetData(meshs[w].vertices);

            //填充緩衝
            shader.SetBuffer(kernel, "blendshapeBuffer", blendshapeBuffer);
            
            //設定權重
            shader.SetFloat("weight", weights[w]);

            //執行Compute Shader
            shader.Dispatch(kernel, 4, 4, 1);

        }

        //獲取計算結果
        vertBuffer.GetData(vertices);

        //更改網格結構
        mesh.vertices = vertices;
    }

    void OnDestroy() {
        if (vertBuffer != null) vertBuffer.Release();
        if (blendshapeBuffer != null) blendshapeBuffer.Release();
        if (naturalBuffer != null) naturalBuffer.Release();
    }
}

效果

原始碼