How to add custom ISM data in Mass plugin?

Development Programming & Scripting C++
, ,
1

I’m trying to use some custom C++ with the mass plugin to add custom data to the Instanced Static Mesh. I’m trying to use exclusively ISM using Anim to Texture plugin to drive animations, but I need to update the Current Frame (ISM Custom Data Index 0). Some of this process is mentioned here: https://dev.epicgames.com/community/learning/talks-and-demos/37Oz/large-numbers-of-entities-with-mass-in-unreal-engine-5

I made a custom state tree task that is supposed to change the custom data but I can’t seem to get it to work without erroring (or doing nothing). Here’s some code with my current erroring:

#include "AnimationOffsetTask.h"

#include "MassCrowdRepresentationSubsystem.h"
#include "MassCrowdSpawnerSubsystem.h"
#include "MassRepresentationSubsystem.h"
#include "MassStateTreeExecutionContext.h"
#include "MassVisualizationComponent.h"
#include "MassRepresentationTypes.h"
#include "Components/InstancedStaticMeshComponent.h"
#include "Misc/LowLevelTestAdapter.h"

using FMassISMCSharedDataMap = TMap<uint32, FMassISMCSharedData>;

bool FAnimationOffsetTask::Link(FStateTreeLinker& Linker)
{
	Linker.LinkExternalData(DataHandle);
	Linker.LinkExternalData(AnimationHandle);
	Linker.LinkExternalData(LODHandle);
	Linker.LinkExternalData(RepresentationHandle);
	return true;
}

EStateTreeRunStatus FAnimationOffsetTask::Tick(FStateTreeExecutionContext& Context, const float DeltaTime) const
{
	const FMassStateTreeExecutionContext& MassContext = static_cast<FMassStateTreeExecutionContext&>(Context);
	FMassEntityHandle EntityHandle = MassContext.GetEntity();
	
	FCustomFloatsFragment* DataFragment = MassContext.GetExternalDataPtr(DataHandle);
	DataFragment->Data[1] = DataFragment->Data[0];
	DataFragment->Data[0] = DataFragment->Data[1] + (DeltaTime*60.0f);

	UMassCrowdRepresentationSubsystem* RepresentationSubsystem = UWorld::GetSubsystem<UMassCrowdRepresentationSubsystem>(Context.GetWorld());
	
	FMassRepresentationFragment RepresentationFragment = MassContext.GetExternalData(RepresentationHandle);
	FMassRepresentationLODFragment RepresentationLODFragment = MassContext.GetExternalData(LODHandle);
	FMassInstancedStaticMeshInfoArrayView ISMInfo = RepresentationSubsystem->GetMutableInstancedStaticMeshInfos();
	if (RepresentationFragment.CurrentRepresentation == EMassRepresentationType::StaticMeshInstance)
	{
		ISMInfo[RepresentationFragment.StaticMeshDescIndex].WriteCustomDataFloatsAtStartIndex(0,TArray{DataFragment->Data[0],DataFragment->Data[1]},RepresentationLODFragment.LODSignificance,2,0,RepresentationFragment.PrevLODSignificance);

//Similar result.	//ISMInfo[RepresentationFragment.StaticMeshDescIndex].AddBatchedCustomData(TArray{DataFragment->Data[0],DataFragment->Data[1]},RepresentationLODFragment.LODSignificance,RepresentationFragment.PrevLODSignificance);
	}
	return EStateTreeRunStatus::Succeeded;
}

This results in the following ensure getting fired off:

void FMassLODSignificanceRange::WriteCustomDataFloatsAtStartIndex(int32 StaticMeshIndex, const TArrayView<float>& CustomFloats, const int32 FloatsPerInstance, const int32 StartFloatIndex, const TArray<uint32>& ExcludeStaticMeshRefs)
{
	check(ISMCSharedDataPtr);
	if (StaticMeshRefs.IsValidIndex(StaticMeshIndex))
	{
		if (ExcludeStaticMeshRefs.Contains(StaticMeshRefs[StaticMeshIndex]))
		{
			return;
		}

		FMassISMCSharedData& SharedData = (*ISMCSharedDataPtr)[StaticMeshRefs[StaticMeshIndex]];

		int32 StartIndex = FloatsPerInstance * SharedData.WriteIterator + StartFloatIndex;
		//This is the offending ensure
		ensure(SharedData.StaticMeshInstanceCustomFloats.Num() >= StartIndex + CustomFloats.Num());

		for (int CustomFloatIdx = 0; CustomFloatIdx < CustomFloats.Num(); CustomFloatIdx++)
		{
			SharedData.StaticMeshInstanceCustomFloats[StartIndex + CustomFloatIdx] = CustomFloats[CustomFloatIdx];
		}
		SharedData.WriteIterator++;
	}
}

I tried to get a hold of the guy who made the post above but could not find a way to contact him (privated social media). Ideally I’d like to ask Mario Palmero how he did this, but as a second best, if someone else can answer, how can I do this? I’d be happy to provide more information.