Re: Check if line is straight

If you really want to check colinearity of three points, you can just multiply vectors:

sub isCorrectPath () {
  my ($x1, $y1, $x2, $y2, $x, $y) = @_;
  return !(($x2-$x1)*($y-$y1)-($x-$x1)*($y2-$y1));
}
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Re^2: Check if line is straight by Anonymous Monk on May 16, 2011 at 20:14 UTC
This is pretty neat, saves a lot of code. What is the best way to add tolerance to this? any suggestions ? Thanks	[reply]
Re^3: Check if line is straight by lidden (Deacon) on May 16, 2011 at 23:13 UTC
`return abs(($x2-$x1)($y-$y1)-($x-$x1)($y2-$y1)) < $tolerance;` Update added `abs()`	[reply] [d/l] [select]
Re^3: Check if line is straight by pajout (Curate) on May 17, 2011 at 11:30 UTC
It depends if you mean tolerance necessary for dealing floats - lidden suggested it already. But if you mean real tolerance, for instance "path is correct if the angle between two vectors is less than 1 degree", you should really compute that value.	[reply]