若要创建绘制命令，请使用 BatchRendererGroup.OnPerformCulling 回调。具体来说，您使用回调的 BatchCullingOutput 参数。此参数包含只有一个元素的 NativeArray。此布局意味着您可以直接修改数组元素的内容，而不用 Unity 无谓地复制数据。NativeArray 中的元素是包含 实际绘制命令 的 BatchCullingOutputDrawCommands 结构。
您的 OnPerformCulling 实现可以生成任意数量的绘制命令。仅使用单个 网格Unity 的主要图形基本体。网格在您的 3D 世界中很大一部分。Unity 支持三角形划分的网格或四边形划分的网格。Nurbs、Nurms、细分表面必须转换为多边形。 更多信息
请参阅 术语表 和材质的简单实现只能输出单个绘制命令，而更复杂的实现则可以输出数千个绘制命令，每个绘制命令具有不同的网格和材质。
注意：为提供最大的灵活性，Unity 不会预分配 BatchCullingOutputDrawCommands 输出结构中的数组，并将它们存储为原始指针，以便您可以轻松地为它们分配内存并从 Burst 作业中使用它们。您必须使用 UnsafeUtility.Malloc 分配数组，且使用 Allocator.TempJob 分配器。该回调不应释放内存。相反，在 Unity 结束使用绘制命令进行渲染后，它会释放该内存。
参阅以下代码示例，了解如何创建绘制命令。此代码示例基于 创建批处理 中的示例。
using System;
using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;
using Unity.Jobs;
using UnityEngine;
using UnityEngine.Rendering;
public class SimpleBRGExample : MonoBehaviour
{
public Mesh mesh;
public Material material;
private BatchRendererGroup m_BRG;
private GraphicsBuffer m_InstanceData;
private BatchID m_BatchID;
private BatchMeshID m_MeshID;
private BatchMaterialID m_MaterialID;
// Some helper constants to make calculations more convenient.
private const int kSizeOfMatrix = sizeof(float) * 4 * 4;
private const int kSizeOfPackedMatrix = sizeof(float) * 4 * 3;
private const int kSizeOfFloat4 = sizeof(float) * 4;
private const int kBytesPerInstance = (kSizeOfPackedMatrix * 2) + kSizeOfFloat4;
private const int kExtraBytes = kSizeOfMatrix * 2;
private const int kNumInstances = 3;
// The PackedMatrix is a convenience type that converts matrices into
// the format that Unity-provided SRP shaders expect.
struct PackedMatrix
{
public float c0x;
public float c0y;
public float c0z;
public float c1x;
public float c1y;
public float c1z;
public float c2x;
public float c2y;
public float c2z;
public float c3x;
public float c3y;
public float c3z;
public PackedMatrix(Matrix4x4 m)
{
c0x = m.m00;
c0y = m.m10;
c0z = m.m20;
c1x = m.m01;
c1y = m.m11;
c1z = m.m21;
c2x = m.m02;
c2y = m.m12;
c2z = m.m22;
c3x = m.m03;
c3y = m.m13;
c3z = m.m23;
}
}
private void Start()
{
m_BRG = new BatchRendererGroup(this.OnPerformCulling, IntPtr.Zero);
m_MeshID = m_BRG.RegisterMesh(mesh);
m_MaterialID = m_BRG.RegisterMaterial(material);
AllocateInstanceDateBuffer();
PopulateInstanceDataBuffer();
}
private void AllocateInstanceDateBuffer()
{
m_InstanceData = new GraphicsBuffer(GraphicsBuffer.Target.Raw,
BufferCountForInstances(kBytesPerInstance, kNumInstances, kExtraBytes),
sizeof(int));
}
private void PopulateInstanceDataBuffer()
{
// Place a zero matrix at the start of the instance data buffer, so loads from address 0 return zero.
var zero = new Matrix4x4[1] { Matrix4x4.zero };
// Create transform matrices for three example instances.
var matrices = new Matrix4x4[kNumInstances]
{
Matrix4x4.Translate(new Vector3(-2, 0, 0)),
Matrix4x4.Translate(new Vector3(0, 0, 0)),
Matrix4x4.Translate(new Vector3(2, 0, 0)),
};
// Convert the transform matrices into the packed format that shaders expects.
var objectToWorld = new PackedMatrix[kNumInstances]
{
new PackedMatrix(matrices[0]),
new PackedMatrix(matrices[1]),
new PackedMatrix(matrices[2]),
};
// Also create packed inverse matrices.
var worldToObject = new PackedMatrix[kNumInstances]
{
new PackedMatrix(matrices[0].inverse),
new PackedMatrix(matrices[1].inverse),
new PackedMatrix(matrices[2].inverse),
};
// Make all instances have unique colors.
var colors = new Vector4[kNumInstances]
{
new Vector4(1, 0, 0, 1),
new Vector4(0, 1, 0, 1),
new Vector4(0, 0, 1, 1),
};
// In this simple example, the instance data is placed into the buffer like this:
// Offset | Description
// 0 | 64 bytes of zeroes, so loads from address 0 return zeroes
// 64 | 32 uninitialized bytes to make working with SetData easier, otherwise unnecessary
// 96 | unity_ObjectToWorld, three packed float3x4 matrices
// 240 | unity_WorldToObject, three packed float3x4 matrices
// 384 | _BaseColor, three float4s
// Calculates start addresses for the different instanced properties. unity_ObjectToWorld starts at
// address 96 instead of 64 which means 32 bits are left uninitialized. This is because the
// computeBufferStartIndex parameter requires the start offset to be divisible by the size of the source
// array element type. In this case, it's the size of PackedMatrix, which is 48.
uint byteAddressObjectToWorld = kSizeOfPackedMatrix * 2;
uint byteAddressWorldToObject = byteAddressObjectToWorld + kSizeOfPackedMatrix * kNumInstances;
uint byteAddressColor = byteAddressWorldToObject + kSizeOfPackedMatrix * kNumInstances;
// Upload the instance data to the GraphicsBuffer so the shader can load them.
m_InstanceData.SetData(zero, 0, 0, 1);
m_InstanceData.SetData(objectToWorld, 0, (int)(byteAddressObjectToWorld / kSizeOfPackedMatrix), objectToWorld.Length);
m_InstanceData.SetData(worldToObject, 0, (int)(byteAddressWorldToObject / kSizeOfPackedMatrix), worldToObject.Length);
m_InstanceData.SetData(colors, 0, (int)(byteAddressColor / kSizeOfFloat4), colors.Length);
// Set up metadata values to point to the instance data. Set the most significant bit 0x80000000 in each
// which instructs the shader that the data is an array with one value per instance, indexed by the instance index.
// Any metadata values that the shader uses and not set here will be zero. When such a value is used with
// UNITY_ACCESS_DOTS_INSTANCED_PROP (i.e. without a default), the shader interprets the
// 0x00000000 metadata value and loads from the start of the buffer. The start of the buffer which is
// is a zero matrix so this sort of load is guaranteed to return zero, which is a reasonable default value.
var metadata = new NativeArray<MetadataValue>(3, Allocator.Temp);
metadata[0] = new MetadataValue { NameID = Shader.PropertyToID("unity_ObjectToWorld"), Value = 0x80000000 | byteAddressObjectToWorld, };
metadata[1] = new MetadataValue { NameID = Shader.PropertyToID("unity_WorldToObject"), Value = 0x80000000 | byteAddressWorldToObject, };
metadata[2] = new MetadataValue { NameID = Shader.PropertyToID("_BaseColor"), Value = 0x80000000 | byteAddressColor, };
// Finally, create a batch for the instances, and make the batch use the GraphicsBuffer with the
// instance data, as well as the metadata values that specify where the properties are.
m_BatchID = m_BRG.AddBatch(metadata, m_InstanceData.bufferHandle);
}
// Raw buffers are allocated in ints. This is a utility method that calculates
// the required number of ints for the data.
int BufferCountForInstances(int bytesPerInstance, int numInstances, int extraBytes = 0)
{
// Round byte counts to int multiples
bytesPerInstance = (bytesPerInstance + sizeof(int) - 1) / sizeof(int) * sizeof(int);
extraBytes = (extraBytes + sizeof(int) - 1) / sizeof(int) * sizeof(int);
int totalBytes = bytesPerInstance * numInstances + extraBytes;
return totalBytes / sizeof(int);
}
private void OnDisable()
{
m_BRG.Dispose();
}
public unsafe JobHandle OnPerformCulling(
BatchRendererGroup rendererGroup,
BatchCullingContext cullingContext,
BatchCullingOutput cullingOutput,
IntPtr userContext)
{
// UnsafeUtility.Malloc() requires an alignment, so use the largest integer type's alignment
// which is a reasonable default.
int alignment = UnsafeUtility.AlignOf<long>();
// Acquire a pointer to the BatchCullingOutputDrawCommands struct so you can easily
// modify it directly.
var drawCommands = (BatchCullingOutputDrawCommands*)cullingOutput.drawCommands.GetUnsafePtr();
// Allocate memory for the output arrays. In a more complicated implementation, you would calculate
// the amount of memory to allocate dynamically based on what is visible.
// This example assumes that all of the instances are visible and thus allocates
// memory for each of them. The necessary allocations are as follows:
// - a single draw command (which draws kNumInstances instances)
// - a single draw range (which covers our single draw command)
// - kNumInstances visible instance indices.
// You must always allocate the arrays using Allocator.TempJob.
drawCommands->drawCommands = (BatchDrawCommand*)UnsafeUtility.Malloc(UnsafeUtility.SizeOf<BatchDrawCommand>(), alignment, Allocator.TempJob);
drawCommands->drawRanges = (BatchDrawRange*)UnsafeUtility.Malloc(UnsafeUtility.SizeOf<BatchDrawRange>(), alignment, Allocator.TempJob);
drawCommands->visibleInstances = (int*)UnsafeUtility.Malloc(kNumInstances * sizeof(int), alignment, Allocator.TempJob);
drawCommands->drawCommandPickingInstanceIDs = null;
drawCommands->drawCommandCount = 1;
drawCommands->drawRangeCount = 1;
drawCommands->visibleInstanceCount = kNumInstances;
// This example doens't use depth sorting, so it leaves instanceSortingPositions as null.
drawCommands->instanceSortingPositions = null;
drawCommands->instanceSortingPositionFloatCount = 0;
// Configure the single draw command to draw kNumInstances instances
// starting from offset 0 in the array, using the batch, material and mesh
// IDs registered in the Start() method. It doesn't set any special flags.
drawCommands->drawCommands[0].visibleOffset = 0;
drawCommands->drawCommands[0].visibleCount = kNumInstances;
drawCommands->drawCommands[0].batchID = m_BatchID;
drawCommands->drawCommands[0].materialID = m_MaterialID;
drawCommands->drawCommands[0].meshID = m_MeshID;
drawCommands->drawCommands[0].submeshIndex = 0;
drawCommands->drawCommands[0].splitVisibilityMask = 0xff;
drawCommands->drawCommands[0].flags = 0;
drawCommands->drawCommands[0].sortingPosition = 0;
// Configure the single draw range to cover the single draw command which
// is at offset 0.
drawCommands->drawRanges[0].drawCommandsType = BatchDrawCommandType.Direct;
drawCommands->drawRanges[0].drawCommandsBegin = 0;
drawCommands->drawRanges[0].drawCommandsCount = 1;
// This example doesn't care about shadows or motion vectors, so it leaves everything
// at the default zero values, except the renderingLayerMask which it sets to all ones
// so Unity renders the instances regardless of mask settings.
drawCommands->drawRanges[0].filterSettings = new BatchFilterSettings { renderingLayerMask = 0xffffffff, };
// Finally, write the actual visible instance indices to the array. In a more complicated
// implementation, this output would depend on what is visible, but this example
// assumes that everything is visible.
for (int i = 0; i < kNumInstances; ++i)
drawCommands->visibleInstances[i] = i;
// This simple example doesn't use jobs, so it returns an empty JobHandle.
// Performance-sensitive applications are encouraged to use Burst jobs to implement
// culling and draw command output. In this case, this function returns a
// handle here that completes when the Burst jobs finish.
return new JobHandle();
}
}
这是 BRG 的最终完整代码示例。如果你将此组件附加到一个 游戏对象Unity 场景中的基本对象，它可以表示角色、道具、场景、摄像机、路点等等。游戏对象的功能由附加到其上的组件定义。 更多信息
请参阅 术语表，在 检查器一个 Unity 窗口，其中显示有关当前所选游戏对象、资产或项目设置的信息，以便你可以检查和编辑值。 更多信息
请参阅 术语表 中设置一个网格和 DOTS 实例化 兼容的材质，然后进入播放模式，Unity 将使用该材质呈现网格的三个实例。