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 Author Topic: algorithm for detecting lines intersection?  (Read 602 times)
lunetta

 algorithm for detecting lines intersection? « on: Oct 3rd, 2004, 3:01pm »

Hello all community
Hope everybody had a nice summer (or nice winter depending on your coordinates)

I'm still dumb after this summer. I was planning to get smarter, but it didn't work out.
Anyway, that's why I can't figure out a simple nice way to detect when two lines with arbitrary coordinates intersect, and the coordinates of this intersection...

Any light?

Frederik

 Re: algorithm for detecting lines intersection? « Reply #1 on: Oct 3rd, 2004, 3:18pm »

Have fun: http://astronomy.swin.edu.au/~pbourke/geometry/lineline2d/

seeya,

Frederik
rgovostes

 Re: algorithm for detecting lines intersection? « Reply #2 on: Oct 18th, 2004, 11:22pm »

If you have the equations for two lines, e.g. y = 0.25x + 6 and y = 3x - 12, you can solve for an equal point (they're a system of equations, after all).

Code:
 Equation 1: y = 0.25x + 6   -0.25x = -y + 6        x = 4y - 24   Equation 2: y = 3x - 12        y = 3(4y - 24) - 12        y = 12y - 84     -11y = -84        y = 84/11 (this is the y value for the interception)          x = 4(84/11) - 24        x = 72/11 (this is the x value for the interception)   .'. the two lines intercept at (84/11, 72/11)     (I know, it turned out to be messy.)
gll

 Re: algorithm for detecting lines intersection? « Reply #3 on: Oct 19th, 2004, 7:52pm »

I had the same kind of problems with geometry. Intersection of two lines, Intersection of a plan with a line, Two plans intersections, Intersection with angles.

So, I took a look to my college's math class. A book on Vector and Geometry was really helpfull. You could look at the Linear Algebra:

ftp://joshua.smcvt.edu/pub/hefferon/book/book.pdf
http://www.netcomuk.co.uk/~jenolive/homevec.html
http://omega.math.albany.edu:8008/mat220/

guillaume LaBelle
lunetta

 Re: algorithm for detecting lines intersection? « Reply #4 on: Oct 21st, 2004, 1:56am »

Hey thanks for all the feedback

and those links were great... I'm studying them
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