// Start is called before the first frame update
void Start()
{
m_BatchRendererGroup = new BatchRendererGroup(this.OnPerformCulling, IntPtr.Zero);
int itemCount = itemGridSize * itemGridSize;
m_itemCount = itemCount;
// Bounds
UnityEngine.Bounds bounds = new Bounds(new Vector3(0, 0, 0), new Vector3(1048576.0f, 1048576.0f, 1048576.0f));
m_BatchRendererGroup.SetGlobalBounds(bounds);
// Register mesh and material
if (m_mesh)
{
m_meshID = m_BatchRendererGroup.RegisterMesh(m_mesh);
}
if (m_material)
{
m_materialID = m_BatchRendererGroup.RegisterMaterial(m_material);
}
// Batch metadata buffer
int objectToWorldID = Shader.PropertyToID("unity_ObjectToWorld");
int matrixPreviousMID = Shader.PropertyToID("unity_MatrixPreviousM");
int worldToObjectID = Shader.PropertyToID("unity_WorldToObject");
int colorID = Shader.PropertyToID("_BaseColor");
// Generate a grid of objects...
int bigDataBufferVector4Count = 4 + itemCount * (3 * 3 + 1); // 4xfloat4 zero + per instance = { 3x mat4x3, 1x float4 color }
m_sysmemBuffer = new NativeArray <Vector4>(bigDataBufferVector4Count, Allocator.Persistent, NativeArrayOptions.ClearMemory);
m_GPUPersistentInstanceData = new GraphicsBuffer(GraphicsBuffer.Target.Raw, (int)bigDataBufferVector4Count * 16 / 4, 4);
// 64 bytes of zeroes, so loads from address 0 return zeroes. This is a BatchRendererGroup convention.
int positionOffset = 4;
m_sysmemBuffer[0] = new Vector4(0, 0, 0, 0);
m_sysmemBuffer[1] = new Vector4(0, 0, 0, 0);
m_sysmemBuffer[2] = new Vector4(0, 0, 0, 0);
m_sysmemBuffer[3] = new Vector4(0, 0, 0, 0);
// Matrices
UpdatePositions(m_center);
// Colors
int colorOffset = positionOffset + itemCount * 3 * 3;
for (int i = 0; i < itemCount; i++)
{
Color col = Color.HSVToRGB(((float)(i) / (float)itemCount) % 1.0f, 1.0f, 1.0f);
// write colors right after the 4x3 matrices
m_sysmemBuffer[colorOffset + i] = new Vector4(col.r, col.g, col.b, 1.0f);
}
m_GPUPersistentInstanceData.SetData(m_sysmemBuffer);
var batchMetadata = new NativeArray <MetadataValue>(4, Allocator.Temp, NativeArrayOptions.UninitializedMemory);
batchMetadata[0] = CreateMetadataValue(objectToWorldID, 64, true); // matrices
batchMetadata[1] = CreateMetadataValue(matrixPreviousMID, 64 + itemCount * UnsafeUtility.SizeOf <Vector4>() * 3, true); // previous matrices
batchMetadata[2] = CreateMetadataValue(worldToObjectID, 64 + itemCount * UnsafeUtility.SizeOf <Vector4>() * 3 * 2, true); // inverse matrices
batchMetadata[3] = CreateMetadataValue(colorID, 64 + itemCount * UnsafeUtility.SizeOf <Vector4>() * 3 * 3, true); // colors
// Register batch
m_batchID = m_BatchRendererGroup.AddBatch(batchMetadata, m_GPUPersistentInstanceData.bufferHandle);
m_initialized = true;
}
// During initialization, we will allocate all required objects, and set up our custom instance data.
void Start()
{
// Create the BatchRendererGroup and register assets
m_BRG = new BatchRendererGroup(this.OnPerformCulling, IntPtr.Zero);
m_MeshID = m_BRG.RegisterMesh(mesh);
m_MaterialID = m_BRG.RegisterMaterial(material);
// Create the buffer that holds our instance data
m_InstanceData = new GraphicsBuffer(GraphicsBuffer.Target.Raw,
(kExtraBytes + kBytesPerInstance * kNumInstances) / sizeof(int),
sizeof(int));
// Place one zero matrix at the start of the instance data buffer, so loads from address 0 will return zero
var zero = new Matrix4x4[1] {
Matrix4x4.zero
};
// Create transform matrices for our 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 expected by the shader
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
// Compute start addresses for the different instanced properties. unity_ObjectToWorld starts
// at address 96 instead of 64, because the computeBufferStartIndex parameter of SetData
// is expressed as source array elements, so it is easier to work in multiples of sizeof(PackedMatrix).
uint byteAddressObjectToWorld = kSizeOfPackedMatrix * 2;
uint byteAddressWorldToObject = byteAddressObjectToWorld + kSizeOfPackedMatrix * kNumInstances;
uint byteAddressColor = byteAddressWorldToObject + kSizeOfPackedMatrix * kNumInstances;
// Upload our instance data to the GraphicsBuffer, from where 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 used by the shader 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 will interpret the
// 0x00000000 metadata value so that the value will be loaded from the start of the buffer, which is
// where we uploaded the matrix "zero" to, so such loads are 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 our instances, and make the batch use the GraphicsBuffer with our
// instance data, and the metadata values that specify where the properties are. Note that
// we do not need to pass any batch size here.
m_BatchID = m_BRG.AddBatch(metadata, m_InstanceData.bufferHandle);
}
