【Unity】万人同屏, 从入门到放弃之——自定义BatchRendererGroup合批渲染海量物体-Toy模板网

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Unity万人同屏动态避障 GPU动画 Entities Graphics高性能合批渲染插件的使用_哔哩哔哩_bilibili

由于Dots的限制太多，对于需要dlc或热更的项目来说，Dots就爱莫能助。能不能不用Entities，只用Entities Graphics呢？

当然是可以的，Entities Graphics背后使用的接口就是Batch Renderer Group；

自定义BatchRenderGroup合批渲染, 可以参考Unity官方文档：Initializing a BatchRendererGroup object - Unity 手册

1. 创建一个BatchRenderGroup对象和Graphics Buffer：

m_BRG = new BatchRendererGroup(this.OnPerformCulling, IntPtr.Zero);

m_InstanceData = new GraphicsBuffer(GraphicsBuffer.Target.Raw,
BufferCountForInstances(kBytesPerInstance, kNumInstances, kExtraBytes),
sizeof(int));

2. 注册需要渲染的Mesh和对应的Material:

m_MeshID = m_BRG.RegisterMesh(mesh);
m_MaterialID = m_BRG.RegisterMaterial(material);

3. 为所有需要渲染的目标创建矩阵数组并传入Graphics Buffer里：

m_InstanceData.SetData(objectToWorld, 0, (int)(byteAddressObjectToWorld / kSizeOfPackedMatrix), objectToWorld.Length);
m_InstanceData.SetData(worldToObject, 0, (int)(byteAddressWorldToObject / kSizeOfPackedMatrix), worldToObject.Length);

4. 把Graphics Buffer添加到BatchRenderGroup进行批次渲染:

m_BatchID = m_BRG.AddBatch(metadata, m_InstanceData.bufferHandle);

创建BatchRenderGroup需要指定一个OnPerformCulling，在相机Culling时自动回调，这里可以直接使用Unity手册里的示例代码：Creating draw commands - Unity 手册

这里我主要测试的使用BatchRenderGroup合批渲染的性能，使用Job System多线程并行修改矩阵数组的位置和旋转，以控制小人移动起来。

控制小人移动的Job System代码如下：

[BurstCompile]
partial struct RandomMoveJob : IJobParallelFor
{
    [ReadOnly]
    public Unity.Mathematics.Random random;
    [ReadOnly]
    public float4 randomPostionRange;
    [ReadOnly]
    public float m_DeltaTime;

    public NativeArray<Matrix4x4> matrices;
    public NativeArray<float3> targetMovePoints;
    public NativeArray<PackedMatrix> obj2WorldArr;
    public NativeArray<PackedMatrix> world2ObjArr;
    [BurstCompile]
    public void Execute(int index)
    {
        float3 curPos = matrices[index].GetPosition();
        float3 dir = targetMovePoints[index] - curPos;
        if (Unity.Mathematics.math.lengthsq(dir) < 0.4f)
        {
            var newTargetPos = targetMovePoints[index];
            newTargetPos.x = random.NextFloat(randomPostionRange.x, randomPostionRange.y);
            newTargetPos.z = random.NextFloat(randomPostionRange.z, randomPostionRange.w);
            targetMovePoints[index] = newTargetPos;
        }

        dir = math.normalizesafe(targetMovePoints[index] - curPos, Vector3.forward);
        curPos += dir * m_DeltaTime;// math.lerp(curPos, targetMovePoints[index], m_DeltaTime);

        var mat = matrices[index];
        mat.SetTRS(curPos, Quaternion.LookRotation(dir), Vector3.one);
        matrices[index] = mat;
        var item = obj2WorldArr[index];
        item.SetData(mat);
        obj2WorldArr[index] = item;

        item = world2ObjArr[index];
        item.SetData(mat.inverse);
        world2ObjArr[index] = item;
    }
}

然后在主线程Update每帧Jobs逻辑，把Jobs运算结果传入Graphics Buffer更新即可：

private void Update()
    {
        NativeArray<Matrix4x4> tempMatrices = new NativeArray<Matrix4x4>(matrices, Allocator.TempJob);
        NativeArray<float3> tempTargetPoints = new NativeArray<float3>(m_TargetPoints, Allocator.TempJob);//worldToObject
        NativeArray<PackedMatrix> tempobjectToWorldArr = new NativeArray<PackedMatrix>(matrices.Length, Allocator.TempJob);
        NativeArray<PackedMatrix> tempWorldToObjectArr = new NativeArray<PackedMatrix>(matrices.Length, Allocator.TempJob);
        random = new Unity.Mathematics.Random((uint)Time.frameCount);
        var moveJob = new RandomMoveJob
        {
            matrices = tempMatrices,
            targetMovePoints = tempTargetPoints,
            random = random,
            m_DeltaTime = Time.deltaTime * 4f,
            randomPostionRange = m_randomRange,
            obj2WorldArr = tempobjectToWorldArr,
            world2ObjArr = tempWorldToObjectArr
        };
        var moveJobHandle = moveJob.Schedule(tempMatrices.Length, 64);
        moveJobHandle.Complete();
        matrices = moveJob.matrices.ToArray();
        m_TargetPoints = moveJob.targetMovePoints.ToArray();
        m_InstanceData.SetData(moveJob.obj2WorldArr, 0, (int)(byteAddressObjectToWorld / kSizeOfPackedMatrix), objectToWorld.Length);
        m_InstanceData.SetData(moveJob.world2ObjArr, 0, (int)(byteAddressWorldToObject / kSizeOfPackedMatrix), worldToObject.Length);
        tempMatrices.Dispose();
        tempTargetPoints.Dispose();
        tempobjectToWorldArr.Dispose();
        tempWorldToObjectArr.Dispose();
    }

Okay，跑起来看看：