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Wednesday, December 19, 2007

Slope Arrow Direction

A coworker was looking for a method to have a slope arrow always point down hill. He saw the method at AU, but couldn't find the handout which had it. I found the method on the AUGI web site. Since I will probably need this in the future, and won't remember that I found it on the AUGI web site, I'm going to post it here in the form of a surface slope label.

The formula to use in the expression is the following:

IF({Surface Slope}<0,0,pi)

Put the expression in the arrow component rotation of the surface slope label, see below:

image

The value of pi is used because the rotation value is in radians. If you want the arrow to go the opposite way, just reverse the second 0 and pi. Now if you use the label the slope of a surface the arrow will always point in the direction you want, but the slope will be positive or negative. You could always drop the sign of the label, but that would be too easy. Another way to do it would be to add another expression:

IF({Surface Slope}<0,-{Surface Slope},{Surface Slope})

4 comments:

J-Fussel said...

Awesome! I always hated that part of labeling and it's dynamic capability.

Anonymous said...

Thank you! I had the same problem...i remembered you could do this put didn't know which handout it was in.

Anonymous said...

I am trying to use this, but I get an invalad input when I put it in the style. Any ideas??????

ChristopherF said...

Are you putting it into an expression? Also make sure that your capitilization is correct for {Surface Slope} and If.

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