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Drastically reduce the cost of UpdateInstances when dealing with a large number of instances or a large number of removes.

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- Perform RemoveSwaps instead of RemoveAts (we don't care about order).
- Cache a mapping from InstanceID to InstanceIndex (in the component's instance data arrays) to provide faster lookup when decided if we've "seen" this instance before.  This is instead of a linear walk of the instance ID array.
- Add some profile markers to the old BatchUpdateTransform function.

#rb Ola.Olsson
#preflight 615f006ecec44a0001316fe3
#lockdown Michal.Valient

#ROBOMERGE-AUTHOR: jason.nadro
#ROBOMERGE-SOURCE: CL 17749760 via CL 17985163 via CL 18367299 via CL 18367329 via CL 18367342
#ROBOMERGE-BOT: STARSHIP (Release-Engine-Test -> Main) (v895-18170469)

[CL 18367374 by jason nadro in ue5-main branch]
This commit is contained in:
jason nadro
2021-12-03 03:45:20 -05:00
parent 8377c52a68 84c652263b
commit 94070216b7
3 changed files with 33 additions and 15 deletions
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6
Engine/Source/Runtime/Engine/Classes/Components/InstancedStaticMeshComponent.h
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@@ -383,6 +383,12 @@ public:
TArray<int32> PerInstanceIds;
/** Used to cache a unique identifier for each instance. These are provided
* by the interface UpdateInstances. This is a map from unique id to index
* into the PerInstanceSMData array.
*/
TMap<int32, int32> InstanceIdToInstanceIndexMap;
private:
/** Sets up new instance data to sensible defaults, creates physics counterparts if possible. */

26
Engine/Source/Runtime/Engine/Private/InstancedStaticMesh.cpp
View File

@@ -3465,9 +3465,11 @@ bool UInstancedStaticMeshComponent::UpdateInstances(
{
// This is an update.
const int32 InstanceId = UpdateInstanceIds[i];
int InstanceIndex = PerInstanceIds.Find(InstanceId);
if (InstanceIndex != INDEX_NONE)
int32* pInstanceIndex = InstanceIdToInstanceIndexMap.Find(InstanceId);
if (pInstanceIndex != nullptr)
{
const int32 InstanceIndex = *pInstanceIndex;
// Determine what data changed.
// Did the transform actually change?
@@ -3553,17 +3555,17 @@ bool UInstancedStaticMeshComponent::UpdateInstances(
{
if (OldInstanceIds[InstanceIndex] != INDEX_NONE)
{
PerInstanceSMData.RemoveAt(InstanceIndex, 1, false);
PerInstancePrevTransform.RemoveAt(InstanceIndex, 1, false);
PerInstanceIds.RemoveAt(InstanceIndex, 1, false);
PerInstanceSMData.RemoveAtSwap(InstanceIndex, 1, false);
PerInstancePrevTransform.RemoveAtSwap(InstanceIndex, 1, false);
PerInstanceIds.RemoveAtSwap(InstanceIndex, 1, false);
// Only remove the custom float data from this instance if it previously had it.
if (bPreviouslyHadCustomFloatData)
{
PerInstanceSMCustomData.RemoveAt((InstanceIndex * PrevNumCustomDataFloats), PrevNumCustomDataFloats, false);
PerInstanceSMCustomData.RemoveAtSwap((InstanceIndex * PrevNumCustomDataFloats), PrevNumCustomDataFloats, false);
}
OldInstanceIds.RemoveAt(InstanceIndex, 1, false);
OldInstanceIds.RemoveAtSwap(InstanceIndex, 1, false);
InstanceIndex--;
}
}
@@ -3585,6 +3587,13 @@ bool UInstancedStaticMeshComponent::UpdateInstances(
}
}
// Rebuild the mapping from ID to InstanceIndex.
InstanceIdToInstanceIndexMap.Reset();
for (int32 InstanceIndex = 0; InstanceIndex < PerInstanceIds.Num(); ++InstanceIndex)
{
InstanceIdToInstanceIndexMap.Add(PerInstanceIds[InstanceIndex], InstanceIndex);
}
// Ensure our data is in sync.
check(PerInstanceSMData.Num() == PerInstancePrevTransform.Num());
check(PerInstanceSMData.Num() == PerInstanceIds.Num());
@@ -3628,6 +3637,9 @@ bool UInstancedStaticMeshComponent::UpdateInstances(
bool UInstancedStaticMeshComponent::BatchUpdateInstancesTransforms(int32 StartInstanceIndex, const TArray<FTransform>& NewInstancesTransforms, bool bWorldSpace, bool bMarkRenderStateDirty, bool bTeleport)
{
CSV_SCOPED_TIMING_STAT_EXCLUSIVE(UInstancedStaticMeshComponent_BatchUpdateInstancesTransforms);
TRACE_CPUPROFILER_EVENT_SCOPE_STR("UInstancedStaticMeshComponent::BatchUpdateInstancesTransforms");
if (!PerInstanceSMData.IsValidIndex(StartInstanceIndex) || !PerInstanceSMData.IsValidIndex(StartInstanceIndex + NewInstancesTransforms.Num() - 1))
{
return false;

16
Engine/Source/Runtime/Engine/Private/PrimitiveSceneProxy.cpp
View File

@@ -609,30 +609,30 @@ void FPrimitiveSceneProxy::UpdateInstances_RenderThread(const FInstanceUpdateCmd
{
if (RemoveBits[i])
{
InstanceSceneData.RemoveAt(i, 1, false);
InstanceDynamicData.RemoveAt(i, 1, false);
InstanceSceneData.RemoveAtSwap(i, 1, false);
InstanceDynamicData.RemoveAtSwap(i, 1, false);
if (bHasPerInstanceRandom)
{
InstanceRandomID.RemoveAt(i, 1, false);
InstanceRandomID.RemoveAtSwap(i, 1, false);
}
if (bHasPerInstanceLMSMUVBias)
{
InstanceLightShadowUVBias.RemoveAt(i, 1, false);
InstanceLightShadowUVBias.RemoveAtSwap(i, 1, false);
}
// Only remove the custom float data from this instance if it previously had it.
if (bPreviouslyHadCustomFloatData)
{
InstanceCustomData.RemoveAt((i * PrevNumCustomDataFloats), PrevNumCustomDataFloats, false);
InstanceCustomData.RemoveAtSwap((i * PrevNumCustomDataFloats), PrevNumCustomDataFloats, false);
check(InstanceCustomData.Num() == (PrevNumCustomDataFloats * InstanceSceneData.Num()));
}
RemoveBits.RemoveAt(i);
RemoveBits.RemoveAtSwap(i);
#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
InstanceXFormUpdatedThisFrame.RemoveAt(i);
InstanceCustomDataUpdatedThisFrame.RemoveAt(i);
InstanceXFormUpdatedThisFrame.RemoveAtSwap(i);
InstanceCustomDataUpdatedThisFrame.RemoveAtSwap(i);
#endif
i--;
}