Hi,
I’m using the default Niagara ‘Grid 3D Gas Fire’ system but it’s not casting any shadows, specifically through the fireplace mesh and it’s iron bars, the shadows only appear because I’ve put in a couple lights inside the fireplace, but the shadows not moving would be the give away. I’m using Lumen and wondering how do I get the fire to cast shadows naturally? in addition to this a particle system also doesn’t appear when playing
current shadow properties of the niagara system
In order to cast shadows and real light, Niagara needs to spawn a particle light.
But with that said, it would be easier to just animate the light inside the fireplace to wiggle around and flicker a bit. Also, increase the source radius of the light. Shadows from a fire should be softer due to the large surface area that the light is emitting from.
While it’s quite impressive what lumen is able to faciliate at the moment, lumen’s interaction with Niagara is quite, quite strange. It can pull light from screen-space, but Niagara fluids don’t propagate world-space lighting, and it’s not exactly clear if they could ever do that. Tracing rays into an emissive volume and hooking that up to the surface cache is probably a bridge too far for lumen. Likely more than what you needed to hear, but that’s just a bit on it.
Unfortunately that guide didn’t help, it doesn’t cast any light or any shadows even with radius up to 500
While what you’re trying should work… The reason I suggest not using particle lights is that it will be extremely expensive to spawn numerous shadowcasting lights in such a small area, when you are really just trying to represent a singular light source. Forget about using Niagara/particles to create the light, and just animate the one light to represent the fire.
You can create a blueprint to slightly wiggle the light intensity, and position. It will look more realistic, be better performing, and be easier to do.
Again, it is critical to increase the source radius of the light. Below is a comparison. Light from an open flame comes from a large surface area, and the shadow should be very soft as a result. The razor sharp shadows are very unrealistic - far worse than being static. You could also use a rect light for a similar effect.
Source radius 30
Thanks! this is a really nice example, I created a BP with a Rec Light but it doesn’t seem to cast shadows at all, ideas?
BONUS! weird effect on character 
created my own solution seen here is realistic fire lighting/shadow possible? - #6 by Jau_Studio
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