What is the best way to find the overlap between 2 sections?

Question

i have Segment class who contain 2 sections , each section contain 2 point the X and Y coordinate.

Point class has getX() and getX() method.

public class Segment
{
    private Point pointLeft;
    private Point pointRight;
}

i want to find the overlap (is there is) between 2 sections:

public double overlap (Segment other)
{

}

how can i find it (only the X axis overlap)

the 2 sections parallel to X axis (each section has the same Y)

What do you mean by "only the X axis overlap"? And do you need the size of the overlap or another Segment defining the overlapping area? — Dmytro Shevchenko, Apr 11 '12 at 15:14
Is this homework? It seems like a very homework-y question. If it is, it should be tagged as such. — raveturned, Apr 11 '12 at 15:15
Very much related: http://stackoverflow.com/questions/3838329/how-can-i-check-if-two-segments-intersect — vcsjones, Apr 11 '12 at 15:15
Also this [How do you detect where two line segments intersect?](http://stackoverflow.com/questions/563198/how-do-you-detect-where-two-line-segments-intersect) — oleksii, Apr 11 '12 at 15:17

score 1 · Answer 1 · answered Apr 11 '12 at 15:17

1

Two points can define a rectangle.

Are you looking for the Rectangle.Intersect method?

http://msdn.microsoft.com/en-us/library/y10fyck0.aspx

answered Apr 11 '12 at 15:17

Steve Wellens

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i update my question - the 2 sections parallel to X axis and the 2 sections parallel to X axis (each section has the same Y) – falukky Apr 11 '12 at 15:23

K Mehta · Accepted Answer · 2012-04-11T15:30:29.160

My understanding of your question is that you first want to project both lines on the X-axis, and then find their intersection.

enter image description here

That is, you want the length of the greyed out section on the X axis in the image above.

You'll want to do it in 4 parts, like this:

if (other.pointLeft.X <= pointLeft.X && other.pointRight.X >= pointRight.X)
    return pointRight.X - pointLeft.X;

if (pointLeft.X <= other.pointLeft.X && pointRight.X >= other.pointRight.X)
    return other.pointRight.X - other.pointLeft.X;

if (pointLeft.X <= other.pointLeft.X && pointRight.X <= other.pointRight.X)
    return pointRight.X - other.pointLeft.X;

if (pointLeft.X >= other.pointLeft.X && pointRight.X >= other.pointRight.X)
    return other.pointRight.X - pointLeft.X;

return 0;

Note, I've coded this in place, and haven't had a chance to test it. But it should give you a basic idea of what needs to be done.

the 2 sections parallel to X axis (each section has the same Y) — falukky, Apr 11 '12 at 16:02
this should still work, because the code ignores the y paremter anyway. — K Mehta, Apr 11 '12 at 16:04

What is the best way to find the overlap between 2 sections?

2 Answers2