Sketch Mode Settings

General

Settings can be found in Sketch | Settings | drop-down menu.
Settings are on/off options: = enabled, = disabled.
The settings you have chosen will remain valid, even if you sometimes leave the sketching mode or open a sketch of another part model.
Note that the context-sensitive function Perpendicular View rotates the model perpendicular to the viewing direction, but does not change the settings.

There are 5 on/off options available

Only wireframe

The geometry of the model is only drawn with lines, i.e. no shading is visible.

You can also see the shape lines behind the sketching surface and it makes it easier to position the sketch lines in some cases.
You can also snap to "hidden lines" so you can use those too when adding constraints.
Allows you to copy the edge lines of features to the sketch plane.

Only draft + references

In the sketch, only the sketch's own lines and the edge lines of the surface selected as the sketching plane are displayed.

Perpendicular

The view is placed perpendicular to the sketch plane.

When this setting is selected, the sketch will automatically rotate perpendicular to the viewer whenever you switch from part modeling mode to sketching mode.
Note that if you rotate the model while sketching and want to return to viewing the sketch perpendicularly, use the context-sensitive function Perpendicular View.

Transparent when shaded

When a part is shaded, it is drawn transparent.

You can also see the shape lines behind the sketch surface and it makes it easier in some cases to position the sketch lines or add constraints to them.
You can also snap to "hidden lines" so you can use those too when adding constraints.

Original geometry visible

Available when editing a sketch.

= The entire geometry of the model is displayed, including the portion that was created after the sketch being edited.
= Only the portion of the model's geometry that was created before the sketch to be edited was made is shown.