Breaking curves produces inexplicable result… not sure what to call this.

[Pentoolist]

Hello Affinity Designer practitioners,

    How to explain? I overlaid a complex curve onto a border (another curve). I need to trim the complex curve and then connect the trimmed curve to the border curve. When I try to break the complex curve (to eliminate the parts I don't want), I get a situation where the fill no longer corresponds to the stroke. It's all over the place. When this happens, it's clear to me that the integrity of the curve is gone.

    I'm using this technique: selecting a node or nodes and clicking "break curves" in the context tool bar. I was able to do this successfully one time, before all hell broke loose (see detail shot).

    I'm not expecting anyone to solve this problem for me, but perhaps guide me in how to think about the problem so I can solve it. The context is I am making a drawing that will be converted to a DXF file, and used to laser cut decorative panels out of sheet metal on a computer-driven laser cutter in India.

    I am way over my head here… thanks in advance. I am remembering that I failed to say thanks to the people that helped me on a previous question. I was unable to use that feedback directly, but it l led me to a workaround. So I do want to say thanks. Thanks!

Any ideas greatly appreciated!

 

   

[Old Bruce]

This may be down to the two different fill modes, Alternate and Winding. It could also be affected by the direction of one of the curves.

I assume you are trying to join these two together.

You have something weird going on because the end nodes appear on the bottom portion only, and the top part is just two middle points so to say. Is this actually a compound curve? Is the layer saying Curves or Curve?

[Alfred]

Instead of trying to do this with the Node Tool, why not use Boolean operations?

1. Select the frame and the branches, fronds, or whatever.

2. Press the ‘Add’ button in the Geometry section of the toolbar (or use the menu command ‘Layer > Geometry > Add’).

3. Draw a rectangle to cover the overhanging parts of the plant.

4. Subtract the rectangle to trim off the overhang.

5. Repeat the above steps for the adjoining frames.

[Pentoolist]

8 hours ago, Old Bruce said:

This may be down to the two different fill modes, Alternate and Winding. It could also be affected by the direction of one of the curves.

I assume you are trying to join these two together.

You have something weird going on because the end nodes appear on the bottom portion only, and the top part is just two middle points so to say. Is this actually a compound curve? Is the layer saying Curves or Curve?

 

8 hours ago, Alfred said:

Instead of trying to do this with the Node Tool, why not use Boolean operations?

1. Select the frame and the branches, fronds, or whatever.

2. Press the ‘Add’ button in the Geometry section of the toolbar (or use the menu command ‘Layer > Geometry > Add’).

3. Draw a rectangle to cover the overhanging parts of the plant.

4. Subtract the rectangle to trim off the overhang.

5. Repeat the above steps for the adjoining frames.

Alfred, thanks! I have been using the boolean add tool. I selected the foliage and the frame and clicked Boolean add, and got a good result, except that I can't just erase the top panel, because it's a continuation of the bottom design, and it will be a separate panel. And it's connected to the leaves on the bottom panel. See Picture 1.

So what I would like to do now is be able to cut the top panel from the bottom panel like you would with a pair of scissors. Then I can Boolean add that top foliage with the top frame. The top panel needs to be a separate element, combining the leaves and the top frame. So doing a boolean subtract like you did in example 3 means I lose the visual elements of that top panel. I'm thinking the workaround for me would be to duplicate the file so I can reverse the process, ending up by subtracting the bottom panel.

So picture 1 is a good result! If I lock the top frame, and disappear it, I get Picture 2. What is the easiest or most elegant way to cut the foliage elements away from the top of the bottom frame without destroying those upper foliage curves? I literally need something like an X-Acto knife that will separate those foliage elements from the bottom frame, and leave them both intact. It seems like the simplest thing, but I do not know how to do it.

Again, Alfred, Thank you!

[Alfred]

2 hours ago, Pentoolist said:

I'm thinking the workaround for me would be to duplicate the file so I can reverse the process, ending up by subtracting the bottom panel.

Your thinking is exactly (X-Actly?) right!

2 hours ago, Pentoolist said:

I literally need something like an X-Acto knife that will separate those foliage elements from the bottom frame, and leave them both intact. It seems like the simplest thing, but I do not know how to do it.

It would be the simplest thing if we had a Knife Tool in the app, but that hasn’t been implemented yet. As you’ve already worked out, you need to make a copy of the parts that you want to reuse for the adjoining frame(s).

[Old Bruce]

An X-Acto knife tool would be great as would a Die Cut method (Cookie Cutter). Die cut would take a closed Curve and slice through by going around.

[Pentoolist]

Thanks Alfred and Bruce! I'm still left with wondering what is the best way to divide a curve shape and have both portions usable. Here is something I saw in Affinity design help:

"Ctrl-click a segment to delete it, creating two separate curves within one curve object."

The big question: What if I want to create two separate curves, each being their own curve object? It seems like it should be on page 3  (or so…) of an Affinity designer manual, but if it is, I have missed it completely.

I need to go back to the affinity design workbook, where I am likely to stumble upon the answer. Thanks for your help, guys!

 

[firstdefence]

2 hours ago, Pentoolist said:

The big question: What if I want to create two separate curves, each being their own curve object? It seems like it should be on page 3  (or so…) of an Affinity designer manual, but if it is, I have missed it completely.

You should be able to use a very very slim rectangle (0.01px) and subtract it from the shape, then Geometry (Boolean) divide.

[firstdefence]

13 hours ago, firstdefence said:

You should be able to use a very very slim rectangle (0.01px) and subtract it from the shape, then Geometry (Boolean) divide.

Just a small update to this...

horizontal rectangles on curved/shaped curves may give corrupt results, if you experience this, I suggest rotating the rectangle or both the shape and rectangle by at least 1.5º this will generally get a nice cut, I've done this with rectangle widths of 0.00001px

You can also do this with a curve drawn with the pen tool and the expand stroke, the reason for this method is to construct a wavy curve. I've also used the pencil tool to get crazy cuts.

 

[Pentoolist]

Alfred, much obliged! I feel like your solution is so easy, it's like cheating… who knew you could do this?

Firstdefense, you are taking it to the next level. It seems like a totally novel way to do stuff, but that seems to be the way this designer program works; if you can think of something and try it, it might just work. Wow!  I'll be trying your technique next.

Thank you all for taking the time to help me.

Pentoolist

 

Here's another mystery: sometimes when I have a shape selected, the electric blue selection line is centered in the stroke, and sometimes it is on the edge, seemingly both conditions can occur on the same curve/shape? What's that phenomenon called, and how can I control it?

Boolean Test 12-12-21.afdesign

[Pentoolist]

Thought I'd better send a JPEG version

[firstdefence]

14 hours ago, Pentoolist said:

Here's another mystery: sometimes when I have a shape selected, the electric blue selection line is centered in the stroke, and sometimes it is on the edge, seemingly both conditions can occur on the same curve/shape? What's that phenomenon called, and how can I control it?

If a blue line is seen in the middle, it indicates a centre aligned stroke, if it's on the outside or inside it indicates an outside aligned or an inside aligned stroke respectively, blue lines on both the inside and outside indicate an expanded curve or a curve that has had geometry subtraction or is a hollow shape like a donut.

[Pentoolist]

Firstdefense, that's a very clear description, but what are the uses for the different blue line positions?

How do you control it? I can't find any documentation on it.

[Alfred]

On 12/14/2021 at 7:34 AM, Pentoolist said:

I can't find any documentation on it.

Try here (also available via the Help within the app):

Affinity Designer Help: Stroke panel

Affinity Designer Help: Expand stroke

[firstdefence]

On 12/14/2021 at 7:34 AM, Pentoolist said:

Firstdefense, that's a very clear description, but what are the uses for the different blue line positions?

How do you control it? I can't find any documentation on it.

You don't control them, they are helper lines, indicators giving you feedback, they help you understand what state the objects are in and what some of their parameters are.

As an example if you add a blur fx to a shape the blue line indicates where the original edge of the object is...

These boundaries also help with snapping and arranging objects.