Welcome to Lesson 5 as we learn to use Inkscape to make scroll saw patterns. This time, we'll be talking about nodes and how to edit them. This could be the most important lesson in the series. We'll really start to see the power of vector graphics to create scroll saw patterns. If you can get a good feel for node editing, there's no stopping you!

If you remember back to the very first lesson, we discussed the difference between vector graphics and bitmap/raster graphics. I basically said that vector graphics are a mathematical representation of an image. This is where nodes come in. An easy way to think of a vector graphic is to think of it as if it was a dot-to-dot puzzle we did as kids. To get to the hidden image in a dot-to-dot puzzle, we'd connect the dots with straight lines in a certain order. In a vector graphic, nodes are those dots. There is a mathematical formula between those two dots that will tell the program where the lines are positioned and whether that line is curved or straight.

When working with shapes with special edit options (square, circle, star, text, etc), you'll have to turn these shapes into a path. This will strip away your special editing options (such as rounding corners, or editing text), but will allow you the freedom to edit the nodes instead. To do this, select your Node Editing tool in the Tool Bar and select your shape. You can click the Convert Selected Object To Path button in the Options Bar and that will convert your shape into a path. You can also convert the object to a path by choosing Path>Object To Path from the menu or by using the keyboard shortcut Shift+Ctrl+C. Now you're ready to edit nodes.

Another option that you may want on occasion is to turn the outline or line into a shape you can edit. To do this, you can choose the button Convert Selected Object's Stroke To Path from the Options Bar. This will change the stroke (outline) into an editable shape. You can also choose Path>Stroke To Path from the menu or use the keyboard shortcut Ctrl+Alt+C.

When you have your object selected with your Node Editing tool, you'll see small diamond shapes at the intersections. These are the nodes. You can select a node by clicking it, and the node will become bold. You can select as many nodes as you want. You can hold down the Shift key and select another node to add to your selection. You can also use your marquee to select multiple nodes. The line between two nodes is called a Segment. By clicking the segment, the two nodes attached to the segment will automatically be selected.

You can move your selected nodes by dragging the node into the proper place. You can also use the arrow keys to nudge them with a bit more control. If you wish to constrain the movement to the X or Y axis, hold down your Ctrl key while dragging the nodes. Nodes do not have to be next to each other to select and move You can select outside nodes, leaving the nodes in the middle selected. When you move those nodes, the center nodes will remain, but the selected nodes will move to where you want them.

You can add additional nodes to any segment by simply double-clicking on the segment. If you want to add a node exactly in the center a segment, select the nodes that make up the segment. Then click the Insert New Nodes In The Selected Segments button (looks like a plus sign above a square) from the Options Bar. This will place a node exactly in the center of the chosen segments. You can do this as often as you'd like, and nodes will continue to be added to the center of the selected segments.

Removing nodes are about as easy as can be. Select the nodes you wish to remove and hit the Delete key or the Backspace key. You can also click the Delete Selected Nodes button from the Options Bar (looks like a minus above a square).

Having straight lines between nodes is fine when roughing in the general shape. But you'll soon want to finesse those lines to make them a bit more graceful and flow. You'll be needing to make these straight lines into curved lines. Creating a curve between nodes is simple. Click and drag a segment and you'll notice that the segment begins to curve. You'll also notice two blue lines with circles at the end appear at each of the nodes on either side of the curved segment. These are called Bezier Handles. (If you don't see the Bezier Handles, click the Show Bezier Handles On Selected Nodes button from the Options Bar.) These handles are what control the depth and sharpness of the curve. By clicking and dragging the circle on the Bezier Handle, you can control how the curve behaves on that node. It will take a little playing to get used to using the Bezier controls to get the curve you want. But once you get a feel for it, you'll be able to get the curve to do exactly what you want it to do. Often, I'll drag the segment out to make a curve and try to get the curve to match as close as possible. I'll then use the Bezier Handles to fine tune the curve to get it exactly where I want it.

When working with curves, you'll be wanting to accomplish different effects. You may want two curves to come together at a point. Other times, you want to be sure that the incoming curve and outgoing curve on a node are smooth. And other times, you'll want the curves to be symmetrical. You can control how a node behaves by clicking one of the node behavior buttons in the Options Bar.

Make Selected Nodes Corner - This option is intended to allow you to create a sharp corner. While this is absolutely true, the reality is that this option removes all restrictions on that node. You have full control over the Bezier Handles. So you can have each Bezier Handle come in at different angles to create a sharp corner, or you can keep them parallel and have the curve smooth out. This option has the most freedom. However, if you want to ensure a smooth transition, one of your other options is better suited.

Make Selected Nodes Smooth - This option smooths out the transition between the incoming segment and the outgoing segment. You'll notice that when you move one Bezier Handle, the other Bezier Handle is parallel and moves with it. This eliminates a nub where the two segments meet. You'll also notice that the length of the Bezier Handles is independent of each other. One handle can be longer than the other, which allows the depth of the curve to be different from one segment to the adjoining segment.

Make Selected Nodes Symmetric - This option works much the same way as the previous option. However, this time, the length of the Bezier Handles is the same on both sides of the node. This will create a symmetrical incoming and outgoing curve.

There are times when an open shape (line drawing) needs to become a closed shape or a closed shape needs to open up to a open shape. We can do that with our segment tools from the Options Bar.

Break Path At Selected Nodes - This tool will split the path (outline) so that you can separate the paths. It will create two nodes out of one. These nodes will become the beginning/end nodes. You'll notice when you move the nodes apart, there isn't a line connecting these two nodes. Basically, you have an open shape (line drawing).

Split Path Between Two Non-Endpoint Nodes - This is similar to the previous tool. But instead of creating a new node, it will remove the segment between the two nodes. Again, you're left with an open shape (line drawing).

Join Selected Endnodes with A New Segment - This will add a new segment between two end nodes. If you have an open shape, select the two nodes where there's only one incoming segment (end node). When you click this button, a straight line will connect these two nodes. You can also use this option to add a segment between two open shapes (line drawings) to create a new open shape.

Join Selected Endnodes - This works much the same way as the previous tool, however, this does not add a new segment. Rather, it moves each end node equally to meet in the center to become one node. You can use this option to close an open shape or to join two open shapes into one open shape.

• Find a few pictures or clip art from the internet that is copyright safe. Pick images that you may someday use for your own scroll saw patterns and start building your own personal clip art library. Using your node editing tools, trace your picture. Be sure to use the Bezier Tool in the Tool Box to create simple lines for interior details