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Control speed with expressions (slow down/speed up)

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Ryan Jones
Control speed with expressions (slow down/speed up)
on Dec 5, 2017 at 2:57:58 pm

Basically, X will be going the rate of time. The slider keyframes will control speed or ramp up and ramp down.

[the slider] has two keyframes; 100 and 1.

the position of the solid is this:
x=(time * 100)
p=effect("Slider Control")("Slider");

There is a nice ease in but then it jumps the second it hits keyframe 1 on the slider. What is a good expression to control the speed of a constantly moving object? Does that make sense?

The animation is a large plane moving at the speed of time and I'd like to control the start and stop, as this large plane will loop in a cycle. Hence the reason for controlling "speed." It doesn't have to stop, but pretty close.

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Andrei Popa
Re: Control speed with expressions (slow down/speed up)
on Dec 6, 2017 at 9:17:21 am

This happens because while time grows slider lowers. And both this increase the speed. So you get an exponential graph with a very steep growth towards the end. I think the solution would be just to lower your slider. Set its value to 4-5 instead of 100.
Graph with max slider at 100.

Graph with 4 instead of 100.

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Ryan Jones
Re: Control speed with expressions (slow down/speed up)
on Dec 7, 2017 at 8:48:39 pm

Interesting. What about stopping? I noticed the object races back to the original X value.

Think of this as a side-scrolling game where the background is moving right to left and your character is centered. The background is looping too, so it's basically sawtoothing or repeating every so many frames. Eventually, I'd like to slow down the background to a stop wherever the x value of the background is. I hope that makes sense. :)

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