4. Drawing commands

All of Asymptote's graphical capabilities are based on four primitive commands. The three PostScript drawing commands draw, fill, and clip add objects to a picture in the order in which they are executed, with the most recently drawn object appearing on top. The labeling command label can be used to add text labels and external EPS images, which will appear on top of the PostScript objects (since this is normally what one wants), but again in the relative order in which they were executed. After drawing objects on a picture, the picture can be output with the shipout function (see shipout).

If you wish to draw PostScript objects on top of labels (or verbatim tex commands; see tex), the layer command may be used to start a new PostScript/LaTeX layer:

void layer(picture pic=currentpicture);

The layer function gives one full control over the order in which objects are drawn. Layers are drawn sequentially, with the most recent layer appearing on top. Within each layer, labels, images, and verbatim tex commands are always drawn after the PostScript objects in that layer.

While some of these drawing commands take many options, they all have sensible default values (for example, the picture argument defaults to currentpicture).