subtracting standard shapes v. custom shapes

[robertmac]

Hi gang,

 

I'm running into something that was confusing at first, and now--an hour later--is frustrating.

 

I'd like to draw an outline around an object in a picture so I can remove it from the image. The object is squarish, so I made a rectangle around it, used the nodes to adjust it just right, and finished "outlining" the thing. 

 

I tried subtracting the outline from the image, and the image from the outline, and sliding the layers of each onto each other in the layers panel. They seem to disappear, which I've seen that others have noticed, too.

 

I've made the outline shape empty (uncolored), and then colored it white (like all the demos show), but no luck. I can accomplish the same thing with the other shapes (ellipse, heart, etc.) but not my custom one. 

 

What am I doing wrong?

 

-R

[MEB]

Hi robertmac,

Welcome to Affinity Forums :)

You can't perform boolean operations between a bitmap and a vector object, only between vector objects. There's quite a few ways to achieve what you want, some depend on the program you are using, which you didn't specify.

 

Assuming it's Affinity Photo you can convert the shape to a selection first. To do this, select the shape, change to the Pen Tool then go to the context toolbar and click the Selection button to convert the shape to a selection. Note that have to convert the Shape to curves first going to menu Layer ▸ Convert to Curves for the Selection button become available. This step is not necessary for "custom" shapes you have drawn with the Pen Tool since they are already curves/paths. After you have converted the shape to a selection, you can simply press Delete on your keyboard to delete it, or copy/paste it to copy the selection and paste it in a new layer.

 

Regarding the "layer sliding" the result will vary depending on what you are dragging (the shape or the image layer) and to where (over the layer or over the layer's thumbnail) in the Layers panel:

 

Layer clipping:

So for example if you drag the image layer over the shape layer (not over its thumbnail but over the area on the right) the image will be clipped - meaning it will only visible inside the area of the rectangle. You can expand the shape layer in the Layers panel (clicking the small arrow inside a circle on the left of the thumbnail) to access the image layer independently.

Doing the opposite - dragging the shape over the image layer instead (again not over its thumbnail but over the area on the right) will clip the shape instead meaning it will only visible inside (the boundaries) of the image. So if you expand the image layer, select just the shape in the Layers panel and drag it on the canvas it will disappear when you reach the border of the image.