LOOKING FOR A LISP ROUTINE

[INTELLIBIRD2]

I am currently working with LDD. I'm not sure if one exists, or how to go about creating one, but I'm looking for a lisp routine that will interpolate an elevation. It would need to work as such: You would be promted to select a point, input an elevation for that point, select a second point, then input an elevation for that point. The lisp would calculate the slope based upon the 2 elevations and the distance obtained from the 2 selection points. Then you would be promted to select a point in between those 2 original points, and the lisp would calculate the elevation for you based upon the obtained slope. This routine would be a tremendous help in obtaining proposed spot grades for a proposed grading plan.

Thank You,
Chris Bird

[rkmcswain]

Do you want to do this without creating LDT points?

[INTELLIBIRD2]

Yes if at all possible. If not, then I will find a work around.

[rkmcswain]

Do you want to pick 2 actual POINT entities?
Could you pick a single 3d LINE entity instead?

Is your 3rd point always going to be on the line defined by the first two points, or will the 3rd point form a triangle?
Are curves a factor, or will this always be three points on a line?

[INTELLIBIRD2]

-I do not want to pick 2 point entities.
-I could pick a single 3d line instead if it gave me the option to input the elevation for each end of the line.
-The 3rd point will always be on the line and not form a triangle.
-It would be nice if it could work with curves as well, such as a 3d polyline with a curve. But I know that adding curves tends to complicate things. So to keep it simple and easy a straight line would work.

[Opie]

-I do not want to pick 2 point entities.
-I could pick a single 3d line instead if it gave me the option to input the elevation for each end of the line.
-The 3rd point will always be on the line and not form a triangle.
-It would be nice if it could work with curves as well, such as a 3d polyline with a curve. But I know that adding curves tends to complicate things. So to keep it simple and easy a straight line would work.

3D Polylines do not have curves.

[kent409968]

What about selecting a 3dline, typing in an elevation and the lisp routing set a point on that line at that elevation?