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Concepts Concepts Structure of a Drawing

Object Types

Sketch has two fundamentally different kinds of objects: primitives and compound objects.

Primitives

Primitives are the basic building blocks of a drawing. They are the ones that actually leave marks on the paper. Among this kind of object are the rectangle, the bézier curve (which also serves as a polygon or even as a straight line) and text object.

Most primitives can have fill properties and line properties. Properties are discussed in more detail below.

Compound Objects

Compound objects group several primitives or other compound objects together into one object. As such, compound objects are invisible, but the primitives contained in them are not. Therefore, compound objects are mainly interesting for editing purposes.

It is often convenient to group the primitives that form a distinctive part of a drawing together into a group. For instance, in the sample file flags.sk each of the flags is a group of several primitives (often just a few rectangles as many of the flags consist of some stripes). Whenever you click on one of the flags the whole group is selected not just the rectangle you clicked on. Thus, most of the time the group is manipulated as a whole (there are ways to work on the parts of a group without ungrouping them first, but that is an advanced topic).

There are some compound objects that behave in a special way. The only example at the moment is the BlendGroup. This group consists of two (or more) control objects and a number of objects that are linear interpolations of the control objects. When you edit one of the control objects all interpolated objects are updated automatically.


Concepts Concepts Structure of a Drawing
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