Topic: limiting angles?

[hudster]

How can I can use lisp to draw a line between a chosen point and a line perpendicular to that point but limit the angle to a maximum of 15 degrees?

***edit***

I'm trying to create a lisp to draw tapers in ductwork based on 4 chosen points.

[whdjr]

I don't know how a line could be perpendicular to a point.

How about a screenshot of what you are trying to do?
Maybe even in steps.

[hudster]

This is what I want to draw, pt1, 2, 3 & 4 will change but the angle must always be a maximum of 15 degrees.

[MP]

Roll yer own lisp that uses grread for the input of the second point, using grvecs to draw a vector at the specified angle as a guide, in this case 15°. Once a point is picked just use standard slope formula to return the point that is on said vector.

[hudster]

Eh?

[MP]

Engrish: Fake out your own polar tracking.

/sorry.

[whdjr]

Here is a post by Stig for Rotating rectangles as you draw them.  It uses GRREAD so it might be of use to you.

Hopr this helps,
 

[CAB]

Hudster,
Questions to consider:
What is the Min Angle?
Do you always start your pick with the larger duct?
When you pick, are you picking the end of two parallel lines for pick 1 & 2?
Are the two lines for the smaller duce already there?
Do you know the size of the smaller duct without measuring it?
Is the reducer always asymmetrical?

I like the direction Will was thinking. A dynamic shape where you anchor the two
corners with picks 1&2 then stretch pick 3 using the Near snap to get one side of
the smaller duct if the two ducts have a common centerline. If centerline is not
the same a fourth pick would be needed.

Just think out loud.

[whdjr]

... If centerline is not
the same a fourth pick would be needed. ..

Why not make it use the centerline as the starting basis and then pick one side and then have it calculate the other side.  That way it's always centered regardless of size.

Unless ofcourse you could be running it along a wall where only one side would transition, but that would an extension of this tool I think.