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Geometry Question

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Message       DaveS           Post subject: Geometry QuestionPosted: Tue Dec 
08, 2009 1:24 am                               
Joined: Sun Aug 05, 2007 10:46 am
Posts: 1808
Location: San Diego, CA              I can't believe that I am unable to come 
up with a simple solution to this

Given two sets of points.... X1,Y1  and X2,Y2...  defines a line of course

What I need to do if adjust the given X2,Y2 point to make sure the resultant 
line is alway at an even multiple of 45 degrees.
0, 45, 90, 135, 180, 225, 270 or 315

Now I don't really care about the specific angle [ie.. a solution that does not 
involve Sine/Cosine match is preferred]

I just need to snap the line on the screen as the user moves the mouse around 
the X1,Y1 center point

For you Windows folks... this is the EXACT same functionality as in MSPAINT 
when you draw a line holding down the SHIFT key     
_________________
Dave Sisemore
MacPro, OSX 10.5.8 RB2009r2  
                            Top               Blake           Post subject: Re: 
Geometry QuestionPosted: Tue Dec 08, 2009 1:47 am                        
Joined: Fri Sep 30, 2005 8:39 pm
Posts: 250
Location: Arlington, TX              Are you calculating the angle at present 
to make sure its not a multiple of 45 or are you starting from scratch?   
                            Top               timhare           Post subject: 
Re: Geometry QuestionPosted: Tue Dec 08, 2009 1:49 am                        
Joined: Fri Jan 06, 2006 3:21 pm
Posts: 6902
Location: Portland, OR  USA              You want one of the following to be 
true:

Y2 - Y1 = 0
X2 - X1 = 0
Abs(Y2 - Y1) = Abs(X2 - X1)

HTH,
Tim   
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