View Full Version : speed up modifier???

09-18-2008, 03:33 AM
I have a null keyframed to go up and down and set to repeat in the graph editor. How can i make this action accelerate with time. Which is the best motion modifier to do this? Forgive me but im not that clued up with using expressions either...but i figure this should be simple for a non idiot!

Im kinda after a super slow motion effect which accelerates up to full speed.

Ive attached a pic to illustrate the kind of graph im after!

09-18-2008, 08:09 AM
You could try out this expression..
[AnotherNull.Position.Y,Time * (Time * 0.25)]

09-18-2008, 08:34 AM
Hey spirosa-that kinda makes sense to me but it no worky worky! Just comes back with the following......"loop detected in expression-position.Y"

Hum...thats what i want isnt it? I think i need to hit the books on expressions!

Thanks for the heads up anyways! Something for me to build on

09-18-2008, 08:50 AM
Hmmm.....I was messing about with this before after I read the post, but was also getting this error.

Completely new to expressions and my maths needs a kick-start so probably no help at all - I have plugins that do what you want, but they're from Worley and cost dosh.

The thing I stumbled on with expressions for this is that you do need looping don't you, so I didn't get how you can do that in a single line expression.

Then there's Relativity of course.....but I couldn't get that off the ground either. Bad news all round really.

One of these coding maths people need to reply and solve it in seconds :D


09-18-2008, 08:58 AM
thanx Julian...nice to know im not the only one stumped! I also think relativity might be the way to go....ive had some terrifying experiences with it in the past but i think its time to show it whos boss!

09-18-2008, 10:31 AM
No wiz at math.

See if this gives you any ideas.

Open up the graph editor and look at the distance null on the z. Right click curve for "show Velocity". I did my best to edit the curve. Not the best solution but it kinda works.

Cyclist follows the null to repeat the up and down motion.

Not sure what you need to do but this might give you an idea.

09-18-2008, 12:00 PM
Relativity is the way to go. It has expressions for just this type of thing and I think theres even an example in the docs.

09-18-2008, 12:27 PM
Cool. Good to know. :)

09-18-2008, 01:35 PM
Relativity is the way to go. It has expressions for just this type of thing and I think theres even an example in the docs.

Are there new docs for this? I have just looked through html docs I downloaded awhile ago, and realised that the tutorials section lists dozens of scene files that demo how stuff works, including an acceleration setup.....I can't find these - anyone know where they are?


09-18-2008, 03:44 PM
Surrealist....you big fat cheat hehe! Visually does the trick but i need a working solution that i can manipulate easily.

Julian checkout the bonus content in the download section. I dont think these are anything new but there are a bunch of sample scenes.

I believe splinegod is refering to the file called 'acceltest.lws' check it out. Its half way to what im after...thanks larry!

09-18-2008, 05:08 PM
No problemo! :)
Relativity has a number of advantages over LW expressions including being able to refer back to themselves.