Complete newbie to VFX here, I’m trying to understand how normal maps play a part in shading a smoke texture to be more realistic in unreal, it will be great if anyone can shed some light on this topic, or provide reading materials/links.
From what I understand, the material shading model has to be set to default lit, and volumetric directional has to be enabled to allow a normal map to be read.
Playing around with paragon smoke textures and my own simple material, plugging in the normal map does nothing to the material in preview, e.g. lighting does not change, not that I can observe anyways.
Also looking at paragon master materials, it looks like they had normal maps but somehow it is being disabled?
So was wondering if normal map matters at all to the shading of these animated smoke textures in any way, and how I can observe the changes in the shading of the texture, when using normal maps.
AFAIC, shading the smoke particle texture with normal map isn’t yet an industrial norm, some games do, but many don’t. My hunch is that today’s 3A games universally use flipbook smoke textures made in Embergen or Houdini, the base color texture itself can get very large for proper sharpness, adding an additional normal map would be too taxing on texture stream budget, so many game devs would prefer to keep the smoke particle material as simple as possible, many would just use volumetric NONdirectional.
As for proper lighting for smoke particle in UE, a cheaper option when working with volumetric directional is to enable “Generate Spherical Particle Normals” which exactly gives the billboard particle a ball like normal so it doesn’t look totally flat when reacting to lighting. (Unity also has a similar built-in spherical normal option in its particle system renderer.)
A bit digress, but it’s a shame that we can’t use Pixel Depth Offset (towards camera), which is unavailable to translucent material, to improve the intersection of the particle billboard with opaque meshes.