View Full Version : Offsetting Actions using MEL

10 October 2005, 01:28 PM
Let's say

I want Car 2 to follow Car 1 in a certain distance. Using this expression
Car2.translateX = `getAttr -time (frame - 5) Car1.translateX`;
is doing well as long as Car 1 is running. If it stops Car 2 will crash into his rear of course.
What I want is that Car 2 stays allways in this certain distance to Car 1, even if Car 1 turns left or right or stops. In other words and to make it more geneal: Car 2 shall reproduce the transformations of Car 2 with a time offset, but keep the distance if Car 1 stops (and goes on after a few frames of resting).

There is a work around using a motion path (and expressions), but I need a solution without this, because I've got a lot of cars, and I want the whole thing get running via MEL.

Could anybody tell me how?

Thanks in advance

10 October 2005, 05:15 PM
Why not calculate the distance in between both cars (or locators) using the mag command and writing a conditional based on that result?
This snippet calculates the distance between 2 particles, but it could get you started:

global proc string getParticleDistance()
float $part1Pos[] = `getParticleAttr -at position[0]`;
float $part2Pos[] = `getParticleAttr -at position[1]`;
float $distancePos[];
$distancePos[0] = $part1Pos[0] - $part2Pos[0];
$distancePos[1] = $part1Pos[1] - $part2Pos[1];
$distancePos[2] = $part1Pos[2] - $part2Pos[2];
float $distance = `mag <<$distancePos[0], $distancePos[1], $distancePos[2]>>`;
return $distance;

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10 October 2005, 05:15 PM
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