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Alex_dlc

How can I draw a trapezoid with curved sides with the Pen tool? Like a nuclear cooling tower shape

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I'm sure the way to do this is really easy, I just can't seem to figure it out. If I start with a curve going up, how can I then make a straight horizontal line? Then I would need another curved line going down, and another horizontal line ending where the first curve started.

 

More or less, this shape:

 page6-1011-full.jpg


iMac 27" · 3.4Ghz Intel Core i7 · 32GB · NVIDIA GeForce GTX 680MX 2GB · 3TB Fusion Drive · OSX 10.11.5

Wacom Intuos Pen and Touch Medium

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1. Make a rectangle

2. Switch to the Node tool

3. Move the top nodes into position

4. Click and drag on one of the slanted vertical "walls"

5. Repeat for the other side

5. Enjoy your new curved trapezoid

 

I'm sure the way to do this is really easy, I just can't seem to figure it out. If I start with a curve going up, how can I then make a straight horizontal line? Then I would need another curved line going down, and another horizontal line ending where the first curve started.

 

More or less, this shape:

 page6-1011-full.jpg


2017 15" MacBook Pro 14,3 w/ Intel 4 Core i7 @ 2.8 GHz, 16 GB RAM, AMD 455 @ 2 GB, 512 GB SSD, macOS High Sierra

2018 11" iPad Pro 256 GB, latest iPadOS public beta

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The above selection works but it's nearly impossible to make sure that your curves are the same when doing it that way.  I have a different approach for you.

 

1. Grab the trapezoid tool and draw your shape.  

2. Convert it to curves.  

3. With the node tool, grab on ONE of the vertical walls and curve it to your desired shape.  

4. Now, duplicate the entire thing using command J and flip it horizontally.  

5. Select both shapes and then click on the intersect boolean.

 

This approach will ensure that both horizontal curves are the same. 

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1. Make a rectangle

2. Switch to the Node tool

3. Move the top nodes into position

4. Click and drag on one of the slanted vertical "walls"

5. Repeat for the other side

5. Enjoy your new curved trapezoid

 

 

The above selection works but it's nearly impossible to make sure that your curves are the same when doing it that way.  I have a different approach for you.

 

1. Grab the trapezoid tool and draw your shape.  

2. Convert it to curves.  

3. With the node tool, grab on ONE of the vertical walls and curve it to your desired shape.  

4. Now, duplicate the entire thing using command J and flip it horizontally.  

5. Select both shapes and then click on the intersect boolean.

 

This approach will ensure that both horizontal curves are the same. 

 

 

But, how can I make it with the pen tool?


iMac 27" · 3.4Ghz Intel Core i7 · 32GB · NVIDIA GeForce GTX 680MX 2GB · 3TB Fusion Drive · OSX 10.11.5

Wacom Intuos Pen and Touch Medium

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You can straighten a segment of a curve, after you've drawn it, by using Alt-click on the segment's handles with the Node tool.

 

I don't know if it's possible to switch from curved to straight as you are drawing. You can switch the Pen tool to Mode: Line in the toolbar, and that works if you are beginning a new curve or if the previous segment was straight; but if there's a previous point that is curved, the next line you draw respects its tangent so the new segment is curved too. (The segment after that will be straight.) That seems wrong to me. We'll see what Matt thinks tomorrow.

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You can straighten a segment of a curve, after you've drawn it, by using Alt-click on the segment's handles with the Node tool.

 

I don't know if it's possible to switch from curved to straight as you are drawing. You can switch the Pen tool to Mode: Line in the toolbar, and that works if you are beginning a new curve or if the previous segment was straight; but if there's a previous point that is curved, the next line you draw respects its tangent so the new segment is curved too. (The segment after that will be straight.) That seems wrong to me. We'll see what Matt thinks tomorrow.

 

Would be great if you could somehow change to straight lines while using the pen tool, for example while holding down shift or alt. It would make it much easier and faster to draw shapes that have both curved and straight edges. 


iMac 27" · 3.4Ghz Intel Core i7 · 32GB · NVIDIA GeForce GTX 680MX 2GB · 3TB Fusion Drive · OSX 10.11.5

Wacom Intuos Pen and Touch Medium

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Hi there … of course you can draw straight path segments along with curved ones and vice versa … the problem is, as Dave has rightly pointed out, that if there’s a point which is the endpoint of a curved path segment (i.e. has an outgoing control handle), the next line you draw respects its tangent, so the new segment is curved too. But when using the Pen Tool, you can

  • (a.) create an independent control handle as a tangent for the next path segment by holding Alt (Option) and by dragging out the control handle on node creation, and
  • (b.) delete a control point by holding Alt (Option) and clicking on that control point. 

Please have a look at my video. And sorry for the multiple edits of my post. Tried to make it as clear as possible … Cheers, Alex  :)

Cooling_Tower.mov

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