# How can I set a UNiagaraDataInterfaceColorCurve from a color curve asset? **URL:** \ **Category:** Programming & Scripting\ **Tags:** unreal-engine, question, CPP\ **Created:** [October 25, 2023, 1:42am UTC](https://forums.unrealengine.com/t/how-can-i-set-a-uniagaradatainterfacecolorcurve-from-a-color-curve-asset/1343769 "2023-10-25T01:42:48Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![CresCoJeff](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@CresCoJeff](https://forums.unrealengine.com/u/CresCoJeff)\ **Post date:** [October 25, 2023, 1:42am UTC](https://forums.unrealengine.com/t/how-can-i-set-a-uniagaradatainterfacecolorcurve-from-a-color-curve-asset/1343769/1 "2023-10-25T01:42:48Z")
I’m experimenting with Niagara, hoping to make a damage numbers particle effect that will normally use an all white color curve scaled by a user parameter to indicate the severity of the damage, and when a critical hit occurs it will instead use a rainbow gradient color curve. I couldn’t find a way within Niagara module scripting to conditionally choose one color curve vs. another, and from what I’ve read this is because significant conditional branches have a heavy impact on code intended to run on the GPU (HLSL generated by Niagara). Instead, I’m trying to set the color curve to use as a Niagara User parameter in C++ and then only the color scale vector changes based on whether or not the damage represents a critical hit (which can be achieved with the selector node). The problem I’m having is that the color curve User parameter is apparently not getting set properly; regardless of the curve I set it to in C++, the particle system uses the default value I provided in the Niagara particle editor for the color curve User parameter. If I unset the default, then the particles become transparent (presumably because the default color curve value is now all zeroes). Here’s the color curve asset loading code: ```auto FString ColorCurvePath = TEXT("/Game/Ryddelmyst_Assets/Textures/"); if (IsCrit) { ColorCurvePath += TEXT("RainbowRoadColorCurve"); } else { ColorCurvePath += TEXT("WhiteColorCurve"); } UCurveLinearColor* ColorCurveAsset = LoadObject ( nullptr, *ColorCurvePath, nullptr, LOAD_None, nullptr ); ``` I wasn’t 100% certain that UCurveLineraColor is the class I want to represent an asset created in the content browser via Right Click → Miscellaneous → Curve → CurveLinearColor, but it looks about right and gives the FRichCurve curve data that UNiagaraDataInterfaceColorCurve seems to want. I’m trying to set the UNiagaraDataInterfaceColorCurve as follows: ```auto UNiagaraDataInterface* DataInterfaceForDamageColorCurve = UNiagaraFunctionLibrary::GetDataInterface(UNiagaraDataInterface::StaticClass(), FloatingNumbersFX_Component, FName{ TEXT("DamageColorCurve") }); if (DataInterfaceForDamageColorCurve) { if (const auto DataInterfaceColorCurve = Cast(DataInterfaceForDamageColorCurve)) { DataInterfaceColorCurve->RedCurve = ColorCurveAsset->FloatCurves[0]; DataInterfaceColorCurve->GreenCurve = ColorCurveAsset->FloatCurves[1]; DataInterfaceColorCurve->BlueCurve = ColorCurveAsset->FloatCurves[2]; DataInterfaceColorCurve->AlphaCurve = ColorCurveAsset->FloatCurves[3]; } } ``` I’ve verified that the variable ColorCurveAsset is non-null after load and that its Keys[0].Value and Keys[0].Time match the asset configuration, so presumably the load operation succeeded. The question then is how should I actually set the color channel curves in the UNiagaraDataInterfaceColorCurve object? The best approach I could see from the API was to set each channel curve individually as seen above, which potentially doesn’t work since I’m seeing the default color curve value used at runtime. ---
**Author:** ![CornReborn](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@CornReborn](https://forums.unrealengine.com/u/CornReborn)\ **Post date:** [July 31, 2025, 9:47am UTC](https://forums.unrealengine.com/t/how-can-i-set-a-uniagaradatainterfacecolorcurve-from-a-color-curve-asset/1343769/2 "2025-07-31T09:47:55Z")
A bit late but just stumbled over this. I had the same problem and looked a bit further into the API. In case you have UseLUT checked in the advanced section of your curve parameter (which it is by default i guess), simply add the following line after setting the curves to update it: ```auto DataInterfaceColorCurve->UpdateLUT(); ``` This did the trick for me! Alternatively to have even less code try this: ```auto if (UNiagaraDataInterfaceColorCurve* AsDataInterfaceColorCurve = Cast(DataInterface)){ AsDataInterfaceColorCurve->CurveAsset = ColorCurveAsset; AsDataInterfaceColorCurve->SyncCurvesToAsset(); AsDataInterfaceColorCurve->UpdateLUT(); } ``` Hope this helps. ---
**Author:** ![Arthur3DLHC1](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Arthur3DLHC1](https://forums.unrealengine.com/u/Arthur3DLHC1)\ **Post date:** [November 21, 2025, 3:54pm UTC](https://forums.unrealengine.com/t/how-can-i-set-a-uniagaradatainterfacecolorcurve-from-a-color-curve-asset/1343769/3 "2025-11-21T15:54:11Z")
I encontered the same problem, and UpdateLUT() do works, but it’s an editor only function, it only works in the UE editor play. When packaging, it will cause failure. ---
**Author:** ![ShadowBr0kerz](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/shadowbr0kerz/32/1201558_2.png) [@ShadowBr0kerz](https://forums.unrealengine.com/u/ShadowBr0kerz)\ **Post date:** [October 19, 2026, 6:56am UTC](https://forums.unrealengine.com/t/how-can-i-set-a-uniagaradatainterfacecolorcurve-from-a-color-curve-asset/1343769/4 "2026-10-19T06:56:01Z")
yeah UpdateLUT being editor only is the killer, it works in PIE then fails in a packaged build. swapping whole data interfaces at runtime was never really supported. simpler approach that survives packaging: keep one color curve on the emitter and drive the tint through a user-exposed niagara color parameter instead, then set it from blueprint each time damage happens. white for normal hits scaled by severity, rainbow values on crit. Expose Niagara Variables C++ & Blueprints, a Niagara variable plugin for Unreal Engine 5, exposes the parameter setters stock leaves out so you dont need custom module code for it: [Expose Niagara Variables to Blueprint & C++ — Set Niagara Parameters at Runtime | Fab](https://www.fab.com/listings/284908d3-8f3a-4430-bece-12ca313608f7)