schupin wrote: ↑
Mon May 07, 2018 5:19 pm
I just took a quick look and there is two things disturbing me :
- why is there a vertical segment on the Y-axis ? (for me it is useless, but I don't know at all what you're drawing )
- The constraint numbered 21 looks odd : it's an equality between segments, but when you mesure the lengths, they are not equal (I did a try with a 30° angle). The vertical length on the y-axis is 0,3048 m, on your part it's 0,3519 m.
The vertical segment represents the culvert centerline (see picture in my previous post).
In case you didn't know, a culvert allows water to flow under a road - think of it as a small bridge... Anyway, when they get placed, they are usually orthogonal to the centerline of the road. If, for some reason, the angle between the road's centerline and the culvert's centerline has to be at an angle other than 90 degrees, we say it's on a skew. That skew is simply the amount above or below 90 degrees. Usually skews tend to be small, up to 15 - 20 degrees, but they can go as high as 65 degrees.
In this case, the skew angle is represented by the constraint at the center of the sketch (labeled "local_skew").
Thus, the vertical line represents the centerline of the culvert. The end of the culvert itself (indicated by the two construction lines) are parallel to the road's centerline and are rotated about the centerpoint by the skew angle. so, to test the sketch, simply adjust the local_skew angle constraint.
So that explains your first question...
To your second question, that's not an equal-length constraint. It's a parallel constraint. You'll see it adjust when you change the local_skew angle constraint.