# Thread: Starting point relative to another point

1. ## Starting point relative to another point

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I can't figure out how to choose my starting point to be relative to another point without drawing help lines (which mean they must be drawn, selected, deleted = time). I am certain there must be a way around this.

For argument's sake, consider I am attempting to draw a cross. I use the line command, input a starting point; choose next point: @100<0 (to draw a line 100 units in length at an angle 0 [relative to X axis] relative to previous point).

Now I need a vertical line of equal length to cross the middle-point of the horizontal one.
I could snap to middle-point, draw a line of half-length at angle 90 and draw another of 2.(length) at angle -90. This produces 2 lines one of which is unwanted must therefore be selected and deleted.

This simple example illustrates my point.

I need a command which allows me to choose my first point (for the LINE command) as the point which is "X" units at angle "alpha" relative to a point "x,y" (or a coordinate selected by the SNAP tool if you will).

Please take into consideration that the solution must be able to satisfy the stated problem and not the chosen example only.

I thank anyone's input in this! Now I gotta put my thinking cap on again...

2. Learn to use Object Tracking Direct Distance Entry and Osnaps.
(forget about using @ relative distances, with object tracking and direct distance entry what you describe becomes trivial)

Maybe someone will come along and post a video (this should have been covered in first day of your class).

BTW - there is nothing wrong with drawing construction (helper) lines when needed.
Offset trim/extend will avoid a lot of these as well.

3. In general, you should investigate the command modifier "From".

In your particular example, once you have drawn one line, then you could copy and rotate about the mid point of the line to give you a cross.

4. First of welcome to Cadtutor. two quick options (there are probably more)
Once you have started your line command, make sure you are in Ortho mode (F, Autocad will prompt you for the first point, from here you can use either
1) type the word 'FROM' then click on the center point of the first line, and then move the mouse upwards and type in a distance of 50, and that will be your starting point
2) type 'TK' which is an abbreviation for tracking point and again pick the center of your first line and move the mouse upwards and type in a distance of 50
this time you will need to press enter a second time to accept this as your starting point (read up on temporary tracking to see what else you can do with this one)

Another one to look at that won't work in your example, but can be very usefull in similar situations is called 'point filters' it's probably better to read up on this one as well.

EDIT the smiley up there should read F8 but an 8 followed by a closing bracket doesn't work as expected

5. "Object Tracking Direct Distance Entry and Osnaps" not sure how to get into this, however I did indeed check out the "From" command and must say, eldon, that that was indeed what I was looking for!
Very useful, I can now use any draw command, use "from" instead of giving an initial point, choose a "from" point, choose an "offset" and I have my starting point just where I need it. (Just stating it for any future readers)
Thank you for helping out a noob, much appreciated!

6. Originally Posted by steven-g
... make sure you are in Ortho mode (F8 , Autocad will prompt you for the first point, from here you can use either
1) type the word 'FROM' then ...
....
I (almost) never use Ortho and have never used From.
I might have to check out that "From", but I doubt I will need it any more often than Ortho. (since Ortho is part of Polar tracking, but limited in functionality - I prefer to work in Polar tracking)

7. Originally Posted by MistaX32
I can now use any draw command, use "from" instead of giving an initial point,....
I'm pretty lazy. I would simply track from the initial point and use direct distance entry. No typing of words for commands.

8. Once I discovered the power of Object Snap Tracking, I no longer had a use for Ortho and never went back.

9. I work in shopfitting, 99.9% of the work is square so I only need horizontal and vertical, hence Ortho.

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Originally Posted by steven-g
I work in shopfitting, 99.9% of the work is square so I only need horizontal and vertical, hence Ortho.
Tracking does so much more, steven, like the topic of this thread. Allowing one to specify a starting point relative to another point without having to call up a modifier like FROM. Plus, it can be left on (almost) all the time without getting in the way. Just think about how many times you hit F8 or whatever way you toggle ORTHO.