On Feb 14, 12:15 pm, "Anush" <itsanushshe...@[EMAIL PROTECTED]
> wrote:
> On Feb 14, 7:51 pm, "Cari Elf" <cbe...@[EMAIL PROTECTED]
> wrote:
>
>
>
>
>
> > On Feb 14, 3:47 am, "Anush" <itsanushshe...@[EMAIL PROTECTED]
> wrote:
>
> > > I have a square grid of unit size. If i have a line between any two
> > > points, how do i find out the number of the intersecting squares.
>
> > > -
> > > Anush
>
> > Well, if you label each cell from (0,0) to (N,N), you can convert from
> > the points to cell coordinates by dividing the point coordinates by
> > the width of a cell. Then all you need to do is find the ceiling of
> > the Euclidean distance between the two points--in other words, round
> > up to the nearest whole integer. This worked with a small test
> > sample, but you should probably test it with several test cases to
> > make sure that it works in all cases. I think that you can do a brute
> > force test using the method described here if you make the Z
> > coordiantes 0:
>
> >http://mathworld.wolfram.com/Line-PlaneIntersection.html
>
> Oh ok..
>
> Correct me if I am wrong.
> so if the grid is from (0,0) to (3,3) and if the line is between
> (0,1 ) and (1, 3) , then the cell coordinates for the line is (0,1/3)
> and and (1/3,1) and then compute the euclidean distance between the
> two points right.
>
> Thanks
>
> -
> Anush- Hide quoted text -
>
> - Show quoted text
Let's say rather that the total size of the grid is 30 pixels by 30
pixels, with 3 cells across and 3 cells down, like a tic tac toe game.
That means that each cell is a 10 x 10 square. Now we have nice
numbers to work with. :)
If you have the points (0,11) and (24,20), divide the coordinates by
10. So your first point becomes (in cell coordinates) (0, 1) and
your second point becomes (2, 2) because we're only interested in
which cell the point is in, not its exact location. Now plug that
into the forumula c * c = (a*a + b * b).
c = sqrt((2-0) * (2-0) + (2 - 1) * (2-1)) = sqrt(2 * 2 + 1 * 1) = sqrt
(4 + 1) = sqrt(5). Round up to 3, and you have your answer.
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