Today seemed like a good day to start a tour through the Drafting Settings dialog box. It's a pretty involved one, with lots of tabs and sub-dialogs, and it contains lots of stuff to help you configure LT to match the way you like to work.
You can launch this dialog by right-clicking on any icon in the Status Bar (except Ortho) and selecting Settings. Which tab you see first will depend on which icon you selected, but I'll start with the "Snap and Grid" tab.
At the top are two checkboxes for activating Snap or Grid; their associated function keys (in this case F9 and F7) are listed next to them in case you don't want to open the box just to turn them on or off.
I'm going to jump down to the bottom of the box first, to the Snap type area. There are three different Snap methods you can use. The first two are Grid snaps, Rectangular and Isometric, and they work along a grid system where the axes are either orthogonal (90 degrees) or isometric (combinations of 30 and 60 degrees). The third snap type, Polar, creates snap intervals along whatever polar tracking angles you happen to be using. It's a little hard to describe, but if you try it you'll figure it out pretty quickly.
Once you've selected a Snap type, you can set your spacing. Since only one Snap type can be active at a time, the spacing for the inactive method is grayed out. In this case, that means that the Polar spacing is inactive. When setting Rectangular spacings, you can choose to force the X and Y spaces to be equal, or you can uncheck the "equal" box and use different values. If you're using an Isometric snap, you only get to pick one value -- the other spacing is calculated based on the value you choose. Same goes for Polar -- you only need one value, since the angle is controlled by another variable (the polar tracking angles).
You can also choose Grid settings on this tab. The Grid is just a visual indicator of distances and spacing -- by itself, it won't help you choose points more accurately, but it will give you a general idea. In typical everyday 2D drafting it shows up as dots, but if you set SHADEMODE to Hidden, the grid becomes lines. It's often used in conjunction with Snap, since you can't see the one and you can't snap to the other.
There are two areas on this tab dealing with Grid settings. Under "Grid spacing", you can set your X and Y spacing (they can be the same or different), and how often you want to see a "major" line, or a line that is darker than the rest. The major line setting only applies when your SHADEMODE is set to Hidden.
Grid behavior controls how the grid looks as you plan and zoom. Turning on Adaptive grid means that as you zoom out, the dots or lines will adjust themselves so you're not left with a completely cluttered screen. Checking the secondary box, to allow subdivision of the grid, means that as you zoom in you get extra indicators, even if you have a wide spacing set. Choosing to display the grid beyond the limits means that it will fill the drawing area, regardless of what the variable LIMITS is set to. Drawing limits used to have more of a practical purpose, when computers were slower, but they're not as widely used any more. Checking this box lets you see the grid anywhere you want to draw.
Well, that's more than enough information for today -- I'll be back next time with everything you wanted to know and more about Polar Tracking.