Adding tracer lines on an object with vectors?

[Walter Soyka]

Vector math needn’t be THAT scary…

Can you make a mockup of how you want you speed lines to work?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Richard Garabedain]

It can be done with particular’s aux system. Or perhaps with the echo effect.

[Ryan Paterson]

Sure, here’s a demoo, super simple. Thanks 🙂

8051_speedlinedemo1.mp4.zip

[Walter Soyka]

Will they always move one way along a straight line like this?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Ryan Paterson]

Just one direction for this project, yes

[Walter Soyka]

I would draw the speed lines in a group on a shape layer, add Trim Paths, and use an expression like this for the End property:

maximumSpeedRange = 250;
s = length(sub(position,position.valueAtTime(time-thisComp.frameDuration)));
ease(s,0,maximumSpeedRange,0,100)

s in this expression is the magnitude of the difference between the layer’s current position and its position on the frame before.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Ryan Paterson]

Ok cool, now if I need them to change directions how would you go about that? When I said one direction I meant one at a time. ie) it moves left then pauses, then moves up and pauses, etc.

[Walter Soyka]

[Ryan Paterson] “Ok cool, now if I need them to change directions how would you go about that? When I said one direction I meant one at a time. ie) it moves left then pauses, then moves up and pauses, etc.”

If you put the lines on a separate shape layer, offset them from the center, and parent the tracer line shape layer to the moving object you could rotate the shape layer according to the direction of movement.

Change the end paths expression to this:
maximumSpeedRange = 8;
p1 = toWorld(thisLayer.transform.anchorPoint);
p2 = toWorld(thisLayer.transform.anchorPoint,time-thisComp.frameDuration);
s = length(p2-p1);
ease(s,0,maximumSpeedRange,0,100)

And add a rotation expression like this:
p1 = toWorld(thisLayer.transform.anchorPoint);
p2 = toWorld(thisLayer.transform.anchorPoint,time-thisComp.frameDuration);
delta = p2 - p1;
radiansToDegrees(Math.atan2(delta[1],delta[0]));

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]