Streams

[captainrex]

Does anyone know how to get the streams to come off of an object like I have pointed out in this pic that I have uploaded? Any help would be grateful!

[Meowx]

I've honestly been wondering how to do a contrail effect like that myself.

[Paul Forwood]

Particles?

[Eric2575]

If I know John3d at all, you'll have a sample project from him in no time

[Rodney]

Not to preempt John but this is ideal FX for splines.

Draw your path... extrude... and adjust to taste.

Add glow and ambience. Adjust settings in the model and chor as necessary.

 

 

I've added two instances of the model over the top of your image as a camera rotoscope showing the effect. In the second model (the red trails on the right) I've changed the blue surface properties of the model to red. The model surface has 90% transparency to let the underlying image show through.

 

For an animated effect, particles may be the easier approach.

[Fuchur]

You may want to have a look at the particle-property "Max distance for emit" or whatever it is called exactly...

 

*Fuchur*

[Meowx]

The problem with particles is that they're always active. The contrail should only appear when the object is moving.

[johnl3d]

I did a simple sample with streaks set up a pose to control them I started at the beginning and then stopped at the end by controling rate of emission

 

 

trail1.mov

 

trail1.zip

 

this is one way

[TheSpleen]

johnl3d is the effects man bar none!

[HomeSlice]

The problem with particles is that they're always active. The contrail should only appear when the object is moving.

You turn particles on and off by animating the "rate of emission" property in the chor or in a pose. I usually set the interpolation method to Linear so it will be more or less predictable.

For this particular effect, you may want to set "Initial Velocity" to "0" or a very low number, so the trail only appears when the object is moving.

[johnl3d]

here is another example using the basic blur sprite

 

 

trail2.mov

 

 

trail2.zip

 

different sprites could give different results this is just another way to get the effect

[Meowx]

Well, that solves one problem!

My other problem with particles is that they don't result in the desired effect. Instead of a nice smooth contrail stream, they're... well, particles.

 

Here, I'll attach some images from Soul Calibur. The weapon contrail effect you see in games like this is more what I'm looking to recreate.

[johnl3d]

here's a possible simple solution or really a rough start in one possible direction

 

 

weapontrail.mov

 

 

weapontrail.zip

 

 

pose controls " trail"

 

 

 

 

another idea would be a dynamic hair image turned on and off by pose

 

On both questions also look at Rodney's idea it is partially done here

[Rodney]

Attached is a failed attempt at the sword effect.

I learned a lot by trying though.

 

It would be useful to know how the game creators designed the effect. I suspect what they have have done is create a circular animation which was applied to a single image.

 

If you can imagine the sword being like the large hand of a clock the movement of the sword would advance the images in the animation leaving a trail effect as it rotates. The image follows the sword wherever it goes regardless of whether its transparent, animated or whatnot.

 

For ease of implementation I'd guess the animation is grayscale (black and white) with the ambience color and intensity adjusted as necessary.

 

In my test I modeled a sickle-like object and rotated it in the Chor. Transparency is by decal and surface properties. The gaff at the end reveals my attempt to use cloth to get a little free flow movement too.

 

Ah well... back to the drawing board.

swordflashzz0.mov

[johnl3d]

Not bad Rodney you just need a pose to turn it on/off on cue

[HomeSlice]

Here, I'll attach some images from Soul Calibur. The weapon contrail effect you see in games like this is more what I'm looking to recreate.

 

Those pictures (game screenshots) look more like frame animations with alpha channels applied to geometry. The animated alpha channel creates the smooth gradation effect. This would take some effort to set up ... but it sure looks cool.

 

As a test, make an animation in After Effects, Image Ready or a free gif animation app of a half circle sweep like you would see on a radar screen. Then convert the frames to TGAs (with alpha channels) and import them into AM as an image sequence. Make a sweeping shape out of patches in AM and attach one end of it to the blade of your sword, then apply the TGA sequence you imported as a cookie-cut decal (you may have to alter your sweeping shape in a new pose so the decal will fit correctly on it). Make a percentage pose for the sword where you animate the frames going from frame 0 (with the pose slider at 0%) to whatever the final frame is (with the pose slider at 100%). Then when you animate the sword in the chor, use the pose slider to animate the glow trail. Just an idea ...

[heyvern]

It appears to me from all of the image examples that the contrail follows the motion path of the ship or object.

 

The trick would be how much "automation" do you need? Are you trying to create the effect or are you like me and want the effect to just "happen" without user interaction? If you are okay with just the final result and not making it "easy" I think this contrail effect that follows the curve of the motion path of the object could be done using a "tentacle" model with bones and a motion path constraint on each bone with a lag. A lot more work but it would give the exact effect you want. Of course you would need to do the "glowyness" of the contrail with a material and some glow. But that could be cool. You could have a material that dissipates and changes color over length or time.

 

The tentacle trail effect would follow the same path as the object. Each bone of the trail would have a lag on the path constraint so it stretches out and then closes back in. This would mean using path constraints to move the object so the trails always follow along.

 

EDIT: Another option using the previous "particle" sprite solution: A render of only the particles with an extreme motion blur on the "trail" particles could eliminate the "particleness" of the streak. This could be composited separately.

 

-vern

[Meowx]

Thing is, it can't just be a simple half-circle cued on and off. The contrail paths PERFECTLY with the weapons through thousands of different moves.

 

This is actually a pretty common effect in video games that I've always wondered about. Another example would be snowboards in the SSX series. Also uploaded a pretty cool example from God of War.

 

Edit: yeah Vern, ideally it would just happen. I experimented with creating a dynamic chain, but was getting problems with it bouncing back and forth instead of collapsing back to nothing.

[HomeSlice]

Maybe you could try creating a short spline, make a group for it, name the group "glow", set to render only lines, give it a glow, constrain it to the object you are animating, and experiment with motion blur settings? Motion blur looks much better in my opinion if you turn multipass off (render with the default A-Buffer renderer).

[Rodney]

This is actually a pretty common effect in video games that I've always wondered about.

 

I'd say its common enough that there should be some information on it on the game forums.

 

You keep moving the target but I think we are seeing your end goal a little clearer now.

 

Keep in mind that the solution won't always be the same for every encounter. I do think an animated image applied to a grid could account for these variations to some extent. Still imagery doesn't show the effect animated so that piece of the puzzle still hasn't been filled in.

 

While these are similar effects I don't think they all use the same methodologies (short of a distortable path grid of some sort). As you are looking for a one-size-fits-all solution that may take some considerable R&D to reach the goal.

 

Is your project a swishing sword, spaceship or object advancing through the frosty morn? Is it a still image or animation? Is it for real time or youtube? The desired end-state is important.

 

Out of those thousand moves how many use the same 'trick'? Are there one hundred different setups? Is there only one. This is important. Why? Because this most likely how many setups you'll have to recreate to match the effect.

 

(I think Holmes was suggesting the half circle only as a test. Keeping the tests simple helps you achieve the basic effect. Then you can move to the next level of complexity.)

[Meowx]

Cool, thanks for the info Rodney. And Homeslice, I never thought of that - I suppose this effect would be more accurately called "simulated motion blur" than "contrails."

 

God of War actually has some pretty good examples of the type of effect I'm looking for. Animated weapon contrails is what I'm looking at here.

Skip to about the 35 second mark to get a feel of what I'm trying to simulate. It's basically glorifying the weapon movement, making for a much more interesting look than the weapons swinging around on their own. Skip to 1:35 to see a simpler contrail with a single weapon.

[heyvern]

My idea wouldn't use dynamic constraints at all. It would be a straightforward path constraint on a chain of bones in the "trail" model that has a fairly dense mesh.

 

In the chor use a path for the object motion and then constrain the "trail" bones to the path with offsets or ease settings. Each bone would also constrain to the model that is moving. The lag would be on that constraint, a small lag (1 or 2 frames?). As the model moves each bone in the trail model would follow along but lag behind 1 or 2 frames.

 

I'll see if I can whip up an example later tonight. I already have a rigged "rope" model that will work. I just need to add new constraints. Remember it would not need dynamic constraints. It would use path constraints so it wouldn't be "automatic". It is the path that causes the trail to bend and warp as it follows the main moving model.

 

-vern

[johnl3d]

go for it Vern that was my next idea

[heyvern]

Ha!

 

Easier than I thought. And it doesn't need a path constraint at all or a very dense mesh.

 

I remember this technique from a long time ago. Someone posted it here or on the mailing list. It was used for a sword swoosh trail EXACTLY like we are discussion. It used an orient and translate constraints with lag... I think. I can't remember the technique or the name of the file. I know I downloaded that file but I can't find it on my machine. As I recall it used a flat mesh model constrained to a sword with a gradient material for transparency at the edges. Looked absolutely fantastic and exactly like those sword trails in the image samples. Wish I could find that file or remember who posted that technique.

 

Anyway, this is as close as I could get and it isn't perfect but the basic idea is there. I used a long thin contrail model with about 10 or so bones... maybe it was 5. Yes 5 bones. 5 spline cross sections. Each bone constrained to the ship has an equal divisible lag. Check the file to see how I did it. I'm too tired to describe it. Also I kept deleting bones as I went along and didn't renumber them... so you got 0, 4, 8, 16, 20.. plus a whole set of other bones I hid but didn't delete... they aren't needed.

 

As the ship moves along the path constraint (I used a path but it isn't needed) the lag on the translate constraints makes the bones follow the exact path... it's a lag so it follows the motion of the ship regardless. I kept thinking lag would... find the shortest route... that is why I thought it would need a path constraint. Silly me. It follows the ships location but those frames behind. So even if it does make a sharp turn the contrail will make the same sharp turn. No path constraint needed. But for a ship a path constraint is the best bet any way.

 

The reason this isn't "perfect" is because when it starts the contrail isn't "pointy". It starts off with the fat end first and each smaller cross section later... not good. There is a way to make it do it right so it starts pointy and ends with the pointy end going back into the ship last. I just haven't figured that out. Basic idea is there I think it's just a different type of constraint or ease or enforcement or something to make it do it right.

 

Looks pretty cool though!

 

p.s. The faster the ship goes the longer the trail as the frames spread out.

p.s. Contrail model has an extra pose in it. Don't use it. Delete it if you want. this is something from another project.

 

contrail.mov

 

project file (v15e)

contrail3.zip

 

-vern

[Paul Forwood]

That looks like a perfect solution to me!

[Rodney]

Nice one Vern!

[steve392]

Thats good Vern ,you quicky trail person you

[NancyGormezano]

Yeah - I like that very much - tis most excellent, sire ! - makes me also think that might be a good technique for a lazy person, such as moi, to automatically animate a mouse's tail (and not use dynamic constraint). I shall have to try that.

 

I will try a control bone that shall whip around, and the individual tail bones will orient like the control bone, with a lag

[johnl3d]

Nicely done Vern

 

I did something like that awhile ago with some worm segments

 

 

dred.mov

 

 

dred.zip

[heyvern]

Ha!

 

Figured out how to have the tail "stream out" at the beginning. Very simple.

 

In the above sample the max lag on the last bone is 10 frames. Go to frame 10 and key ALL the bones lag value at the amount that is already there. You just want that key. Go back to frame 0 and key the lag for all bones to 0. Now as each bone is pulled along the tail stretches out as the ship moves. When the ship stops moving the tail collapses. Works great.

 

If you want the project I could post it but... it only takes about a minute to key those bones... it's a good learning experience.

 

This whole thing could probably be set up with a pose so you only need to key one pose of the contrail model. Maybe have the lag value for each bone linked to an expression to a pose slider and you could stretch or shorten the trailing effect by keying a pose. This is pretty cool. It could be used to create engine exhaust/flames that cut in and out... add some noise to the pose keys controlling the lag and the jet stream would "vibrate" etc.

 

-vern

[heyvern]

Oh heck...

 

(In this animation you can see the start and end of the trail. In the other project the end is fine but the start wasn't right so I cropped it out of the render.)

 

contrailB.mov

 

contrail4.zip

 

-vern

[NancyGormezano]

Mousetail using this method works wonderfully! I've tried dynamic constraints - (with spring, not spring, different drag values) - and could never get this nice kind of motion, with a shaped tail. All bones in tail are lagged by 2 frames from previous bone in chain for a total lag of 20 frames at the tip.

 

Dynamic constraints that are baked have an advantage of being able to manipulate the bones after simulation. But are less easy to control motion.

 

Thank You Thank You Thank you - Captain Rex for asking the question and Vern and others for providing an answer!

taillagbothcompressed.mov

[Meowx]

Looks pretty sweet, Vern! I'll play around with that and post some results.

[HomeSlice]

Very nice guys. That's what I love about this forum.

[heyvern]

Mousetail using this method works wonderfully! I've tried dynamic constraints - (with spring, not spring, different drag values) - and could never get this nice kind of motion, with a shaped tail...

 

That looks great! I really wasn't sure how you would use this for a tail. I kept having images of a poor mouse running and running because if it stops its tail would zoom up inside it like a retractable cord on a vacuum cleaner.

 

The Mouse Tale

by Vern Zehr

 

"Hello Mr. Mouse!"

"Hello Mrs. Robin."

"Mr. Mouse why do run so? Won't you stop and have some tea?

"No Mrs. Robin. If I stop running my tail will retract AND KILL ME!"

"Oh... uh... better keep... moving. Some other time then?"

"ZZZRRRRRRPPPPPTTTT!! CRACK!!!! AAAAAAHHHHGGGG!!"

"Oh my!"

 

The End

 

-vern

[Meowx]

hahaha.

 

All right fiddled around with the lag and settings, further tweaking to come; I tacked it onto a test animation I had done earlier. This is exactly what I was looking for. Awesome idea, Vern!!

test_act2.mov

[heyvern]

Thanks Meowx! Great job.

 

Just to be clear this "idea" was inspired by my memory of someone elses brilliant idea from a long time ago. I hope to find that original sword swoosh file on a back up or old hard drive and hopefully determine the source of it. I'm glad I remembered as much as I did... uh... actually I'm SURPRISED I remembered as much as I did.

 

The other exciting potential would be having the "pre rigged" or constrained "trail" model with poses. You could drop in as many as you want to create bunches of overlapping streaky trails. Just line them up with whatever part of the object you want a streak coming from. Adjust the poses to change the length and "duration" of the streaks for variety.

 

-vern

[heyvern]

Wracking my brain on how to make the contrail model work with any model in a chor. I added a "target" bone. That target bone is the target for the translate and orient constraints for the other trail bones. Then when you drag the contrail model into a chor you only constrain the target bone to your model. The other bones follow along. So you can then drag any number of contrail models and put them anywhere you want.

 

A few other details to work out and then I will post the project.

 

-vern

[heyvern]

I started a new thread for the model/project and download here:

 

http://www.hash.com/forums/index.php?s=&am...st&p=300404

 

-vern