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Just like any other actor.

So a fast moving projectile with a small radius would take more steps than a similar projectile with the same speed but a larger radius?

Fast projectiles cut their movements in smaller steps. At least eight steps, but it can be more. (If the x or y velocity per step is larger than the fastprojectile's radius, then the number of steps doubles, which halves the velocity per step.)

But presumedly (haven't looked at any code here yet) the special spawns X actors in the space between its current position and its previous position, else we're back to the whole "Why not do this once a tic with A_Spawn" problem. So then could we change the value of X to increase the number of particles spawned, thus closing the gaps?

For the record, I'm not saying any of this would be a good idea. :) But in some circumstances (such as very fast / slow projectiles) it may be useful to adjust the particle density.

No. The spawning is done per movement step. So the spacing only gets smaller when the speed decreases.

Can you control the spacing between actors with this new implementation? Because then you could set them to appear one map unit apart (possibly less?) and get as close to an uninterrupted "beam" as the Doom engine will allow.

Granted it would also lag some computers, but there are many effects that can do that already...

I think someone -- Captain Toenail again, perhaps -- has a working implementation of a beam weapon that uses a similar "Dalek" method (that's catchy) that actually spawns the trails correctly, taking into account the player's pitch. Unless it was my imagination, but I sure hope not... at any rate, the MageWand trail itself helps immensely to achieve such an effect, I say.

Theoretically, if the FastProjectile moves at slower speeds -- 50, perhaps -- will the trail be even denser?

Also, q has been exterminated. :P

Well i don't actually need a fully continuous method. I've alrady tried the "Dalek" method before with the old Hellfire wand (that shot out the two super-fast rippers) and all it did was cause horrendous lag and the eventual crash. For some reason, i never bothered to just make it shoot a recolored Mage-wand shot thinking that only 1 projectile can have the trail (I remember reading that somwhere a long time ago)). Anyway, as long as it looks as tightly packed as the mage wand missile, it's perfectly fine.

And if you employed the "Dalek method" by having the smoke trail actor spawn items at fixed positions relative to it, it might be possible to fill in some of the gaps even further.

The description is a bit inaccurate. The effect is called several times per tic, actually. The MWM has a speed of 184, and you can see there's much less than 184 map units between each sparkle.

I think i should rephrase the question. What i meant was, say the projectile had the sped of 256, using A_SpawnItemEx every tic would great 1 trail actor every 256 units, making it look VERY spread out, as opposed to the Mage wand missile that has spawns the trails certain distances away from the next requardless of the speed. I was just wondering if there is a difference.

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One effect thsat can work quite well is in the Daleks mod (Captain Toenail?). The missile spawns some cutstom actors at fixed distances behind it. It works very well when the missile is fired horizontally but the steeper the gradient of firing, the more it looks like a series if dashes.

Horizontal (p= Dalek, q= target :P)
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Angled
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[quote="Gez"]It's not exactly possible to create a continuous trail using finite, discrete actors.[/quote]
And it would totally blow your mind (and computer) to do so.

It results in precisely the same type of trail as the MageWandMissile. Which, you've probably noticed, is indeed discontinuous. It's not exactly possible to create a continuous trail using finite, discrete actors.
[url=http://img443.imageshack.us/i/screenshothexen20091005.png/][img]http://img443.imageshack.us/img443/2153/screenshothexen20091005.png[/img][/url]

I'm a bit confused about the fast projectile's trail using Missiletype. It states that a actor specified is spawned every 1 tic as the missile moves. Wouldn't that have the same results as just using A_SpawnItemEx ever 1 tic, resulting in a discontinuous trail?