If you need to match a contiguous selection of texture vertices to an outline in a bitmap, whether an irregular shape, a straight line, or a geometric shape, you can use the Sketch tool to perform the operation quickly, rather than dragging the vertices one at a time.
Example: To sketch texture vertices free form:
You can start with the vertices already selected, or use the Sketch tool to select them. This example uses the latter method.
The mouse cursor takes the form of a circle, which means you're in “drag select” mode.
As you drag, each vertex is assigned a consecutive number. When you release the mouse button, the cursor turns into a pencil, which means you're in “sketch” mode.
The selected vertices follow the line in numeric order, spreading out evenly over its length. To start the sketch over, release the mouse button, and then drag again.
Alternatively, if you press and hold
, and then press and release the mouse button, you'll draw a straight line by moving the mouse. Click and move again to draw connected straight-line segments.
You can combine free-form and straight-line sketching freely:
key and then begin dragging.
as you drag, and then release the mouse button and move the mouse. 
Lets you choose how to select the vertices to sketch:
+click) to sketch. As with Pick Selection, the mouse cursor continues to alternate between Select and Sketch modes until you right-click to exit. Lets you choose how to sketch:
+click to sketch connected Displays numbered labels that indicate the order in which vertices were selected and will spread out during sketching.
Shows vertex positioning as you sketch. Turn off for faster feedback.
Sets the size of the mouse cursor used while dragging a selection. Default=8. Range=1 to 15.
Accepts the changes and closes the dialog.
Undoes any changes and closes the dialog.
Makes the current settings the defaults for the current session.