Tutorials

This section contains tutorial introductions to the capabilities of TreeMaker. I will walk you through the basic process of setting of a TreeMaker design and constructing a crease pattern. The tutorials are:

Tutorial 1: Designing a Base

In this tutorial, you will work through the design of a 4-legged animal with a head and tail and will learn the fundamentals of designing a model with TreeMaker. Before starting it, you should understand the fundamentals of origami design, such as the difference between corner, edge, and middle flaps and be familiar with the basic origami procedures and terms such as valley fold, mountain fold, reverse fold, rabbit ear, et cetera.

TreeMaker designs an origami base that can be represented by a stick figure. You specify the desired proportions of your base by drawing a stick figure in the square and specifying its dimensions. If you have ever used a vector drawing program like Macromedia Freehand, Adobe Illustrator, Deneba Canvas, Corel Draw, etc., you should have no trouble in figuring out how to draw a figure, but if you haven't, we'll walk you through it.

Begin by double-clicking on the TreeMaker icon to launch it. This will create a new, untitled window that displays a square --- the default shape of paper. Later, you will see how to change the size and shape of the paper (you can even design for a rectangle if you like) but for now we'll use a square.

If TreeMaker is already running, you can create a new, untitled document by selecting the File->New menu command.


Figure Tu-1-1. A new, untitled TreeMaker document shows a blank square.

Initially, the square is blank. We will define the tree by drawing on the square, but the tree is really an abstract concept. Several points on the tree correspond to distinct, identifiable points on the square, so as a matter of convenience we will draw the tree on the square.

Even before we've drawn anything, there is one important attribute of the design: the scale, which is always displayed in the bottom of the design window. The scale is the ratio between the characteristic size of the base and the size of the square, so larger is better: a larger scale gives a larger base in the end. The scale always starts out with a value of 0.1, but over the course of the design, we will find a better value for this quantity.

Click once in the middle of the square. You will see a dot appear with a number above it and a circle around it as in Figure Tu-1-2. This dot is a node; the number is the index of the node, which is used to identify the node later on. Each node is assigned a unique index. You can ignore the index for now. If you clicked just once, the node is a big dot, which means that it is selected. If the node is a small dot, it is deselected. A node represents either the tip of a flap or a point where multiple flaps come together. The circle represents the amount of paper required to form the flap whose tip is represented by a node.


Figure Tu-1-2. A single node in the new tree.

If exactly one node is selected and you click somewhere else, a new node will be placed at the click location with a line connecting the nodes. The line between the two nodes is called an edge. We'll do this now. Make sure the node is selected (click once on it so that it is highlighted) and then click once above the node; you have now created an edge connecting the two nodes. Note that the new node is now selected (highlighted), as is the edge, as shown in Figure Tu-1-3.


Figure Tu-1-3. Two nodes and an edge in the tree.

The edge displays two numbers near its midpoint: the index, which serves to identify the edge, and another number below it, which is the desired length of the edge. The length of the edge is proportional to the length of the corresponding flap on the base. The proportionality constant is the aforementioned scale.

All edges start out with a length of 1.000 by default; later you'll learn how to change the length of an edge. Note too that the displayed length of the edge doesn't change when you drag nodes and edges around. This is an important point: the displayed length is not the actual length of the drawn line; it's the desired length of the corresponding flap.

There are two types of nodes in a tree. Leaf nodes are nodes that have only one edge incident upon them. Branch nodes have two or more edges incident upon them. Leaf nodes correspond to the tips of flaps; branch nodes correspond to points where multiple flaps come together. Leaf nodes (and only leaf nodes) are drawn with circles around them; the radius of the circle is the scaled length (edge length times tree scale) of the incident edge. The size of the circle indicates the minimum area of the paper needed fr the flap that corresponds to the incident edge; longer edges mean larger circles. Larger circles consume more paper, leaving less paper for other parts of the tree. The process of designing a uniaxial origami base amounts to laying out the nodes in a way that insures that every flap gets the right amount of paper; the node circles provide some visual feedback of how much paper is needed by the leaf nodes --- or rather, by the edges that are incident to the leaf nodes.