Procedural Mesh Component Hangs When New Section is Drawn

Development Programming & Scripting C++
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1

I’m trying to generate a terrain procedurally. On tick, I check to see which tiles fall within a specific radius from where the player is and if they are not drawn, draw them as a new section via the procedural mesh component attached to the actor.

I’m dispatching a worker thread to handle geometry generation, which could take a few seconds. However, drawing them as a section on the procedural mesh component MUST be done in the game thread. There’s an assertion check somewhere in the call. This means that after the player approaches a new tile and it has been generated, there’s a noticeable 1-second lag when the game hangs before the tile is added and the game thread continues working again.

void ATerrain::AsyncDrawTile(int32 TileX, int32 TileY) {
	UE_LOG(LogTemp, Display, TEXT("ATerrain::AsyncDrawTile(%d, %d)"), TileX, TileY);
	// Dispatching a worker thread to generate the tile data.
	AsyncTask(ENamedThreads::AnyThread, [this, TileX, TileY]() {
		FTileData TileData;
		UKismetProceduralMeshLibrary::CreateGridMeshWelded(...);
		// Adjusting the location of the vertices.
		for (auto &Vertex: TileData.Vertices) {...}
		// Calculating normals and tangents. Quadratic complexity. It's going to take a while.
		UKismetProceduralMeshLibrary::CalculateTangentsForMesh(...);
		// Jumping back to the game thread because CreateMeshSection can only be called from the game thread.
		AsyncTask(ENamedThreads::GameThread, [this, TileX, TileY, TileData]() {
			// Clearing the section if it exists, or getting a new section index.
			const auto SectionIndex = GetClearSection(TileX, TileY);
			// Adding the mesh section to the vertex buffer.
			ProcMeshComp->CreateMeshSection(
				SectionIndex,
				TileData.Vertices,
				TileData.Triangles,
				TileData.Normals,
				TileData.UV0,
				TileData.VertexColors,
				TileData.Tangents,
				true // Collisions
			);
			// Assigning the auto material if any is set.
			if (Material) {
				ProcMeshComp->SetMaterial(SectionIndex, Material);
			}
		});
	});
}

Is there any workarounds or alternative methods that would avoid blocking the game thread?

Thanks.

2

Try setting ProcMeshComp->bUseAsyncCooking = true;