Once a guide is active and properly set up, you can use it to assist you in creating a drawing with perspective. The guide will display its axes going through your mouse cursor as you move it inside your drawing space. When you start drawing a stroke, your drawing tool will become locked to the axis that most closely matches the angle of your stroke, forcing you to draw a straight line along that axis, as if you were using a ruler or a set square.
Guides can only be used with the Brush, Pencil or Line tool. The selected guide will only be visible when one of these tools is selected.
In the Tools toolbar, select the Brush , Pencil or Line tool.
In the Guides view, select the guide you wish to use.
In the drawing area, draw a stroke with the current drawing tool. From the initial gesture, the tool locks on one of the guide's axes, forcing it to draw a straight line that follows the axis.
NOTE Some guides do not lock onto a horizontal or vertical axis line by design. At any time, when drawing with the Brush or Pencil tool, you can hold down Shift + Alt before starting the stroke; this will force the tool to draw a straight line that locks at every 15 degrees. You can also achieve the same effect with the Line tool by holding down Shift before drawing a stroke.