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As I mentioned last time, the building blocks I owned as a child were the result of my father's woodworking. Not every block was perfectly proportioned into neat geometric shapes. Sometimes, they were oddly shaped, or, as wood often is, shaped by splitting along the grain line rather than being cut by the saw. Some had curved patterns where their opposites were used to trim a chair or cabinet. I didn't discard these irregular shapes but embraced them. Not everything in our world is created from straight lines, ellipses, and circles. With this in mind, we continue our look into LibreOffice Draw by learning how to create polygons, arcs, and curves. A polygon is a plane object with at least three straight lines and angles. In geometric terms squares, rectangles, and triangles are types of polygons. For our purposes, we will discuss polygons with more than four sides. An arc, in Draw, is a partial circle or oval. You can make them filled or empty. A curve is a bent line. We will look at two methods for creating curves, the curve tool itself and the Bezier method.
Comme j'ai dit la dernière fois, le jeu de cubes que j'avais dans mon enfance avait été fabriqué par mon père qui travaillait le bois. Elles n'étaient pas toutes parfaitement proportionnées dans des formes géométriques claires. Parfois, elles était bizarres ou, comme souvent avec le bois, elles était créées en fendant le bois selon son fil au lieu d'être découpées avec une scie. Certaines avaient une forme courbée où leurs contre-parties avait été utilisées pour faire une chaise ou une armoire. Je n'ai pas mis ces formes irrégulières au rebut, car elles me plaisaient beaucoup. Tout dans notre monde réel n'est pas créé à partir de lignes droites, d'ellipses et des cercles.
Dans cette perspective, nous continuerons notre examen de LibreOffice Draw et apprendrons à créer des polygones, des arcs et des courbes. Une polygone est un objet plan avec au moins trois lignes droites et trois angles. En termes géométriques,
Drawing Polygons
As I said, a polygon is an object with multiple sides. In Draw, you have four polygon tools. Two enclosed and filled polygon tools, and two open and unfilled polygon tools. The unfilled polygon tools are good for making a series of lines. For both types, you have a free-form version and a version restricted to angles that are multiples of 45 degrees. To create a polygon, select one of the polygon tools from the Lines extended toolbar. Click and drag to create the start point of the first line. When you release the mouse button, the end point of the first line is created. Move the mouse to the position where you want the end point for the next line and click. Continue until you have created all the lines for your polygon. Double-click on the last point to end the polygon. If you are using one of the filled polygon tools, the end point of the last line will automatically connect to the start point of the first line, enclosing the polygon.
If you use one of the filled polygon tools, Draw fills the polygon with the currently selected fill color and sets the lines to the currently selected line color. You can change these using the Line and Fill toolbar or the color bar.
Add Circles and Ovals Toolbar
For quick access to the arcs and segments tools, we need to add the Circles and Ovals toolbar to the Drawing toolbar. Right-click the Drawing toolbar and select Customize Toolbar. This opens the Customize dialog. Click the Add button. Select Drawing under the Category list. In the Commands list, find the Ellipse tools – there are two. You want the one with the description “Using Customize toolbar, you can add the Ellipse icon which opens the Circles and Ovals toolbar.” Click the Add button. Click Close to close the selection dialog.
Using the up and down arrows, move the new icon to where you want it on the toolbar. I placed mine below the Ellipse tool. We don't really need the Ellipse tool any longer as it is included in the Circles and Ovals toolbar. Uncheck the Ellipse tool. Click the OK button, and you should see the toolbar is now on your Drawing toolbar.
Drawing Arcs or Segments
To draw an arc or segment, select one of the tools from the Circles and Ovals toolbar you just added. Click and drag to create a containing circle or oval. Release the mouse button. Click in the circle or oval where you want the arc or segment to begin. Move the mouse around the circle or oval to create the arc or segment. Click a second time to create the end point for the arc or segment. The status bar will show you the angle from center of the points as you move around the circle or oval. This can help you create accurate and precise arcs and segments.
Drawing Curves
A curve is a bent line rather than a segment of a circle or oval. To draw a curve, select the curve tool from the line toolbar. Click on the start point and drag to draw a line. Release the mouse button at the peak point for your curve. Move the mouse to bend the line to the point where you want the curve to end. Double-click to complete the curve.
Bezier Curves
A Bezier curve is a smooth curve with a start point, an end point, and two control points. The mathematics behind the Bezier curve is beyond the scope of this article, but you don't need to understand the math in order to draw one. To draw a Bezier curve, select the curve tool from the lines toolbar. Click at the start point, drag to the end point and double-click. Click on the Points tool on the Drawing toolbar (F8 on the keyboard), and the Edit Points toolbar is displayed. Select either the start or end point (the start point is the larger square). Select the Smooth or Symmetric Transition tool from the Edit Points toolbar. A dashed line and circle will appear indicating the control point for that point. Move the control point to create the curve for that point. Repeat these steps for the other point.
Conclusion
Since not all things are created from straight lines, ellipses, and circles, the creators of Draw gave us more tools for creating objects. A polygon can create an object with more than four sides. Arcs and segments gives us parts and segments of a circle or ellipse. Curves give us the ability to bend a line into different shapes. With these extra tools in hand, Draw lets you create more advanced images for your documents.