keywords: UE5, Groom, Hair, Fur, Performance Optimization

Cases

How to change groom material at run-time

Add matertial slots in the Material tab of Groom Asset editor, then switch material by index.

if (AActor* Actor = UGameplayStatics::GetActorOfClass(this, ACharacter::StaticClass()))
{
	if (UGroomComponent* Groom = Cast<UGroomComponent>(Actor->GetComponentByClass(UGroomComponent::StaticClass())))
	{
		const TArray<FHairGroupsMaterial>& MatGroup= Groom->GroomAsset->HairGroupsMaterials;
		if (Index >= 0 && Index < MatGroup.Num())
		{
			if (UMaterialInterface* Mat = MatGroup[Index].Material)
			{
				Groom->SetMaterial(0, Mat);
			}
		}
	}
}
How to switch groom LOD at run-time

Add LOD group in the LOD tab of Groom Asset editor, then switch groom LOD by index.

UGroomComponent* Groom = ...;
Groom->SetForcedLOD(2);

Performance Optimization

Groom Asset Performance Optimization

Reduce Curve Decimation and Vertex Decimation in Interpolation detail panel.

Disable Voxelize and Use Stable Rasterization in Strands details panel.

Issues

Issue: How to fix the flickering in groom hair [UE4]

Enable Cast Deep Shadows in light actors.

Origin:
https://www.youtube.com/watch?v=4d7H3bEaXsw

Issue: The target skeletal mesh could be missing UVs
LogHairStrands: Error: [Groom] Binding asset could not be built. The target skeletal mesh could be missing UVs.
LogHairStrands: Error: [Groom] Binding asset could not be built. Some cards guide roots are not close enough to the target mesh to be projected onto it.
LogHairStrands: Error: [Groom] The binding asset (11_2_head_Binding) couldn't be built. This binding asset won't be used.

Reason:
The origins of the coordinate axes of the hair and the character are not match.

Misc

References

Hair Rendering and Simulation
https://dev.epicgames.com/documentation/en-us/unreal-engine/hair-rendering-and-simulation-in-unreal-engine

Groom Asset Editor User Guide
https://docs.unrealengine.com/5.3/en-US/groom-asset-editor-user-guide-in-unreal-engine/

XGen Guidelines for Hair Creation
https://docs.unrealengine.com/5.3/en-US/xgen-guidelines-for-hair-creation-in-unreal-engine/

Create Hair in Unreal Engine 5 | Groom Tutorial Works in UE5
https://www.youtube.com/watch?v=gxp0FxyTflc

How to Create Hair in Unreal Engine 5 - Groom Tutorial
https://www.youtube.com/watch?v=ODkhcRvcaso

Groom (Hair & Fur), a brief overview of how Groom (hair & fur) works in Unreal Engine 4.
https://dev.epicgames.com/community/learning/tutorials/p4BG/unreal-engine-groom-hair-fur

Assets

Cyberpunk Hair is a groom game-optimized pack ready to a vast amount of styles
https://www.unrealengine.com/marketplace/en-US/product/cyberpunk-hair-for-game

Tools

Ornatrix UE5 plugin. Hair and fur editing suite inside Unreal Engine!
https://ephere.com/plugins/epic/ue/ornatrix/

gFur is a free shell based fur solution for Unreal Engine.
https://www.unrealengine.com/marketplace/en-US/product/gfur-5
https://github.com/GiM-GamesInMotion/gFurPro

In a group of many words, there is bound to be a mistake somewhere in them. -Chinese Proverbs