Welcome to Lesson 4 as we learn to use Inkscape to create scroll saw patterns.

In this lesson, we're going to learn to create complex shapes by using additive and subtractive tools. With these tools, we can take any number of simple shapes to create unique shapes. These tools are found under Path menu. We'll be discussing Union, Difference, Intersection, Exclusion, Division, and Cut Path. We'll also touch briefly on Combine and Break Apart.

These tools will play a vital role in creating our scroll saw patterns, so take some time and play with them. On the plus side, using these tools is very easy to understand and explain, so this lesson should go fairly quickly.

Begin by creating two shapes (square and circle) and place them so they're overlapping a bit. Make sure they have a fill and stroke color assigned. We'll use these two shapes to demonstrate how our Path tools work. After testing each of the tools, you may want to undo (Ctrl+Z) the transformation to get back to your original square and circle.

Union will merge (weld/melt) two objects together to create a single object. Try selecting your square and circle, the choose Path>Union. You'll now notice the two objects merged into one object. The stroke now goes around the perimeter of the new shape. This is the easiest way to make complex shapes and will be your most used tool in the Paths menu. It is worthwhile to learn the shortcut keys Ctrl++ (hold down the control button and press the plus key).

Difference is the exact opposite of Union. Instead of merging two objects, one object subtracts from the other. This will use the concept of a cutter. The cutting shape will be the shape on top. Select your square and circle, then choose Path>Difference. You'll notice that the top object cuts into the object below. Hit Ctl+Z to undo the Difference to get back to your original square and circle. Now change the object order and repeat the process. You'll now see that you get a completely different shape, based on what shape is your object, and which shape is your cutter. This will be your second most used tool in the Paths menu. It is worthwhile to learn the shortcut keys Ctrl+- (hold down the control button and press the minus key)

Intersection will take two overlapping objects and leave the overlap area as your new shape. Select your square and circle and choose Path>Intersection. You'll see immediately that the overlapped area is all that remains from your two objects.

Exclusion is the exact opposite of Intersection. Instead of leaving the overlapped areas, the overlapped areas will be removed, leaving behind a hole. Select your square and circle and choose Path>Exclusion. You'll notice the overlapping areas are now a hole, and the remaining parts of your two objects are now one object.

Division is similar to Difference in the fact that it requires a cutter. Your cutting object is the object on top. This option will take your top object and cut the bottom object where they intersect. Select your square and circle and choose Path>Division. You'll notice your top (cutter object) disappears. What you're left with is the same shape as your original bottom object, but now its in two pieces. Select the area where they overlapped and move that cut piece away. You'll also notice that the cut edge of the cut piece has the same shape as the cutter.

Cut Path works much the same way as Division, but instead of a solid object, it cuts the path (outline) instead. This option also requires the cutter to be on top. Select your square and circle and choose Path>Cut Path. Your bottom object will be converted into a path (outline). Where the two objects intersected, the path will be cut into two paths. With your Selector Tool, move the overlapping path away. Now you have two separate pieces of line art.

This tool is a little complicated to wrap your head around, but it will play a role when we start editing nodes. We'll also use these options when working with text so we can work with individual letters.

Combine will take two objects and make them into one object. Unlike Union, the two shapes still remain. However, the lines of the two shapes now become sub-paths. The advantage of Combine is that you can use your node editor (we'll be discussing the next lesson) and edit the nodes of all the shapes that were combined. When using Combine, your shape-specific transformation tools (like rounding square corners) will be lost.

Break Apart is the opposite of Combine. It will take one object, and separate them into separate pieces. This allows easy manipulation of shapes within the original object without relying on node editing. Once your editing is done, you can select all of your pieces and Combine them once again to make a single object.

• Try putting together a shape by using each of the Path tools (excluding Combine and Break Apart).
• Once you have your shape put together, try playing with Combine and Break Apart (Break your shape apart first).