10 Replies Latest reply on Mar 25, 2010 11:29 AM by Tom Tomasko

# How to constrain length of handle?

Hello,

I have a right triangle where the hypotenuse is a concave curve. I have to manipulate this triangle so that it can be a filler between  between two crossing strokes. The strokes will be at different angles so that the right triangle will become either obtuse or acute.

The two things that must remain consistent are the two equal sides of the triangle and the handles that moderate the depth of the curve. It is no problem to keep those side equal because I temporarily place a circle with its center underneath the triangles main angle, making sure the strainght sides of the triangle are equal to the radius. But when I move the handles so that I can make the curve very nicely blend in with the straight strokes, I see no way to constrain the length of the handles. I do not see anything in the controls that tells me the length of the handles.

Any suggestions?

Tom

• ###### 1. Re: How to constrain length of handle?

Heh,   ... you said hypotenuse.

You should be able to simply click and drag to lengthen/shorten the control handles on curved path segments.
• ###### 2. Re: How to constrain length of handle?

Yes, I can click on the handle and make it longer or shorter. That is precisely what I want to avoid. While moving the angle of the handle I want the length to remain exactly what it is.

Tom

• ###### 3. Re: How to constrain length of handle?

Those handles are the descriptions of the Bezier curve which is the line shown. If you change the line those handles have to change.

• ###### 4. Re: How to constrain length of handle?

It is impossible to constrain the length of these handles.

I'm not sure why it would matter if the handles moved or became longer/shorter, as long as your curve has the correct appearance/shape.

• ###### 5. Re: How to constrain length of handle?

Then you're only able to move it along the arc of a circle centered on the vertice of the angle, if I understand you correctly.

• ###### 6. Re: How to constrain length of handle?

Turn on smart guides (CMD+U) and it would snap along the smaller circles. That would be one way to go about it.

• ###### 7. Re: How to constrain length of handle?

Like this:

• ###### 8. Re: How to constrain length of handle?

Tom,

The two things that must remain consistent are the two equal sides of the triangle and the handles that moderate the depth of the curve. It is no problem to keep those side equal because I temporarily place a circle with its center underneath the triangles main angle, making sure the strainght sides of the triangle are equal to the radius. But when I move the handles so that I can make the curve very nicely blend in with the straight strokes, I see no way to constrain the length of the handles. I do not see anything in the controls that tells me the length of the handles.

It sounds as if you use the Direct Selection Tool to move the Anchor Points at either end of the curved side, and then try to rotate the handles without changing their lengths.

However, even if you do that, which is possible, that would change the fundamental shape of the curved side because its length is changed. You can see it clearly if you create a two point curved path and strecth/compress copies of it.

It would seem more obvious to keep the fundamental shape of the curved side with the same relative depth, in other words keep the handle length proportional with thetotal length, which is also possible.

When you have the basic triangle, an intersection between the two lines to be followed, and the circle, the latter may be done in the following way, Smart Guides being your friend to help snapping:

1) Place the centre of the circle and the right angle of the triangle at the intersection of the lines;

2) Create a straight path and move the end points to the intersections of the circle and the lines;

3) Rotate the triangle round the right angle to snap one acute angle to one of the intersections in 2);

4) Rotate the triangle round the angle in 2) to snap the other acute angle to the connecting line;

5) With the Scale Tool drag the acute angle in 4) to snap the other intersection;

6) DirectSelect the right angle and drag it to the centre of the circle/intersection of the lines;

7) Delete the circle and the connecting line.

Similarly, the former may be done in the following way:

1) Place the centre of the circle and the right angle of the triangle  at the intersection of the lines;

2) Create a straight path and  move the end points to the intersections of the circle and the lines;

3) Rotate the triangle round the right angle to be roughly parallel with the connecting path in 2);

4) Create a copy of the connecting line in 2) and use the Arrows to nudge it to more or less coincide with the endpoints of the curved path;

5) Adjust the rotation to snap/fit and get the right angle;

6) DirectSelect each of the acute angles and drag them to snap to the intersections of the circle and the lines;

7) Delete the circle and the connecting line(s).

• ###### 9. Re: How to constrain length of handle?
The strokes will be at different angles so that the right triangle will become either obtuse or acute.

Your description makes no sense. Neither an obtuse nor an accute triangle is a right triangle. Any right triangle with two equal length sides would be a 90, 45, 45 triangle--all such triangles would be similar. If the curved side (!) of this triangle is concave, I don't understand "very nicely blend in with the straight strokes."

Strokes are attributes that can be applied to paths. Those paths can be curved, straight, open, or closed. You're using the word "strokes" where you should be using "segments."

Post an image of what exactly you are trying to do.

While moving the angle of the handle I want the length to remain exactly what it is.

Assuming the anchorPoint has but one handle (which it should if the adjacent segment is straight), simply select the anchorPoint and rotate it. Its extended curve handle will rotate it with it, but will not change length.

JET

• ###### 10. Re: How to constrain length of handle?

Hello,

It appears that the answer to my question is no, one cannot constrain the length of a handle. So from the suggestions here I have done the next best thing. Create two concentric circles and put their centers on the intersection of two strokes. Then move the apex of the triangle to that point. Then move the other two anchors of the triangle to intersect with the outer circle and the handles of those anchors to intesect with the inner circle. Please see the image below.

Using the same concentric circles I can move them around to the many sharp intersection I have so that I can fill in those intersections in a consistent manner. What is shown below is one fillet of an X. I have to make several more letters with fillets, so consistency is important. Of course many of the intersections are at different angles.

I hope that newer versions of Illustrator would make it simple to set the length of a handle so that when moving it around it stays the same length.

Tom