Confusion about trails

Hello !

Kind of special topic, but after doing some researches about trails, I’m confused about how many things fall in the topic of “trails”. Keep in mind I’m not a vfx artist at all but I like doing some effects when I can.

I see so many different ways of creating trails but I don’t really know how each of them are used to create different effects. I’ll be more precise (sorry it’ll be long).

  • Starting from the most basic, we can spawn individual particle being a moving object (with some shader or flipbook), usually for smoke or simple fire trail.

  • Then we have the stretched ribbons : a texture streched on a ribbon, the head of the ribbon attached to the object. I think this is one of the most used trail since it can create simple but effective trail with the most basic texture (like a circle), but it can also create really cool trails with good handpainted texture and some shader magic. Only thing that they can’t do, is “staying in place”, since the UV will follow the head, the tail of the trail (oof) will be draged by the object anywhere it goes, and it’s a problem that doesn’t seems to have a simple solution.

  • There is also the tiled ribbons : cool for repeating a texture along a trail, but it needs a seamingless texture and any shader that you apply to the texture will be repeated on every tile, meaning for example that you cant scroll a noise on the whole trail, only on every tile independently, which usually breaks the effect and show the tiles. Maybe there is a way to avoid that I’m not aware of ?

  • Finally, the last “type” of trail I know : trail meshes. A flat mesh with a scrolling texture. Useful when we know in advance the trajectory of the object. Weapon swing animations are usually “static” so we can pre-bake a trail mesh and scroll the swing texture on it during the swing animation to get a nice and smooth curve. Again, one problem : if you want your mesh to always face the camera (like a ribbon particle), you have to do some mesh deformation and I don’t even know how. If anyone know how you can do that I would gladly read about it (and try to implement it myself).

So yeah, that’s a summary of most methods I’ve seen to create trails. I’m using Unity and VFX Graph myself so I know how to do most of them (minus the questions I added obviously) at a very ugly and basic level, but I wanted to ask if there anything I missed, and if some methods are more used than other.

If you read the entire thing, thank you a lot, I know it’s a lot but I’m basically trying to sort all of this myself and my tiny brain is starting to melt.

  • Stretched Ribbon
    The solution is actually fairly simple! You needs to just scroll the texture of the trail using shader. However, the question is more about do you want it to just stretch or do you want it to have some sort of motion.
    A simple stretched texture is widely used for ‘motion line’ since it does not have to have and obvious pattern.
    The trail with scrolling texture is used mostly to emulate a ‘ribbon’ kind of smoke (like when you blow a candle out) and some more magical things.
    It’s up to the prompt and your preference, really.

  • Tiled Ribbon
    I mostly saw this used as like, a trail of chain or vines, (or a path of pointers/arrows, something like that), anything that can have like repeated tiles of texture and get away with it.
    But if you really want to break the tile, a simple solution is to sample the texture one more time, but with multiplier for UV not equal to 1, then add the texture with normal 1x UV with one with irregular UV.

  • Mesh Trail
    I saw it once in passing but there was a really cool trick to make the mesh looks good facing the camera without ‘flattening’ and thus disappear (I assume that is what you are going for?), you can do like a flattened croissant mesh. Like, make the usual curve/fan/etc. mesh BUT extrude it so that it have slight thickness (and maybe smoothing it a bit). Then you cut UV in half along the border, then stack the UV shell on top of each other.

    With some bloom, the slight thickness will give off an illusion of the trail having volume.
    You might also needs to set the material for this kind of ‘thick trail’ mesh to one-sided, since it might looks wonky with top and bottom side stacking with texture.

There is also a matter of texturing, size along trail manipulation, and corroding the texture so that the trail looks more interesting. Study from references and keep practicing and you will get it eventually!

Thanks again for the answer !

I think you confirmed most of what I understood about trails, I’ll try to solution you gave me. For the stretched ribbon, I don’t think it will fix it thom the trail will still be dragged around. I was looking at this post Breakdown of ghost trail , there is some scrolling noise as you said, but the end of the trail is still moving with the head. It works great for this effect, but it can’t simulate smoke that stays in place once spawned.

For the mesh trail, it’s not what I meant, but still a good idea, thank you ! What I was talking about was basically how to achieve the ribbon effect (or trail renderer) : each square of the trail looking at the camera while still keeping the same curve. Twisting the trail if you want. I know it’s something like the cross product of the trail direction and the vector to the camera, just have to work on it. It could be useful for the effect in my other post.