Subtracting Shapes¶
Introduction¶
In this tutorial we are going to draw a shape and subtract another shape from it. We assume that you know how to draw a circle using the {{l|Circle Tool}} and a rectangle using the {{l|Rectangle Tool}}. If not then check {{l|Circle Tool|here}} and {{l|Rectangle Tool|here}}.
Drawing the shapes¶
Click the {{l|Circle Tool}} on the {{l|Toolbox|toolbox}} and draw a circle on the canvas with an outline of 3 pixels. Make sure that the create region layer and the create outline layer in the {{l|Tool Options Panel}} of the {{Literal|Circle tool}} are selected.
Click the {{l|Rectangle Tool}} on the {{l|Toolbox|toolbox}} and draw a rectangle on the canvas with an outline of 3 pixels. Again make sure that the create region layer and the create outline layer in the {{l|Tool Options Panel}} of the {{Literal|Rectangle tool}} are selected.
For the sake of this example name the circle outline layer ‘’’circleOutline’’’ and the circle region layer ‘’’circle’’’ in the {{l|Layers Panel}}. Again in the {{l|Layers Panel}} rename the rectangle region layer ‘’’baseShape’’’ and name the rectangle outline layer ‘’’baseShapeoutline’’’. If it is not already the case then select the ‘’’circleOutline’’’ layer and the ‘’’circle’’’ layer and move them to the top using the green arrows in the {{l|Layers Panel}}. Select all layers in the {{l|Layers Panel}}, right-click and choose group. Name the group ‘’’baseShape’’’.

Layers Panel should look like this
Subtracting the shape¶

Canvas should look like this
Click on the ‘’’circle’’’ layer in the {{l|Layers Panel}} or on the circle shape in the canvas and select the green handle in the middle of the circle and drag it over the ‘’’baseShape’’’. Release the mouse.

Drag the circle

Canvas should look like this
Select the ‘’’circleOutline’’’ layer in the {{l|Layers Panel}}, go to the {{l|Parameters Panel}} and change the {{Literal|Blend Method}} of the ‘’’circleOutline’’’ layer to {{Literal|Onto}}. Select the ‘’’circle’’’ layer in the {{l|Layers Panel}}, go to the {{l|Parameters Panel}} and change the {{Literal|Blend Method}} of the ‘’’circle’’’ layer to {{Literal|Alpha Over}}.

Parameters Panel with blend method of Circle layer and CircleOutline layer

Outline Width is not the same
The circle layer was subtracted from the ‘’’baseShape’’’ but the {{Literal|Outline Width}} of the cut out part varies from the {{Literal|Outline Width}} of the ‘’’baseShape’’’. To adjust this we have to change the {{Literal|Outline Width}} of the ‘’’circleOutline’’’ layer. Select the ‘’’circleOutline’’’ layer in the {{l|Layers Panel}}, go to the {{l|Parameters Panel}} and change the {{Literal|Outline Width}} to 6 pixels. After we adjusted the {{Literal|Outline Width}} of the ‘’’circleOutline’’’ layer the ‘’’circle’’’ layer was subtracted correctly from the ‘’’baseShape’’’.

Final image
Tip¶
If we want to add a ‘’’circle’’’ to the ‘’’baseShape’’’ then all we have to do is change the {{Literal|Blend Method}} of the ‘’’circleOutline’’’ layer from {{Literal|Onto}} to {{Literal|Behind}} and change the {{Literal|Blend Method}} of the ‘’’circle’’’ layer from {{Literal|Alpha Over}} to {{Literal|Composite}}.

Circle added to the baseShape
Below we can see an image of a piece of cheese that is almost entirely constructed by subtracting and adding circles to a basic underlying shape.

All holes in the cheese image are subtracted circles