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POAABB outline to AABB outline intersection points algorithm?
 

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  1. POAABB outline to AABB outline intersection points algorithm?
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    <p>I've looked around but haven't exactly found what I'm looking for. At first, I thought this would be a simple problem.. Until I tried to implement it and realized there were many cases and I could not find a generic solution.</p> <p>Say, I have two AABBs. If their outlines intersect, I want to get all their points of intersection. The <strong>maximum</strong> amount of points is <strong>4</strong>, the <strong>minimum non-zero</strong> amount of points is <strong>1</strong>.</p> <p>My AABBs are composed of a <code>min</code> and <code>max</code> point that are always automatically sorted so that <code>min</code> always has the <strong>lowest</strong> x-y values and <code>max</code> always has the <strong>highest</strong> x-y values.</p> <p>The image below shows a few AABBs. The blue lines indicate their points of intersection. Note that if a side of an AABB overlaps another side, it's kind of like having an infinite amount of intersection points along the line-segments that overlap; in those cases, I want to ignore them and say, "There are no intersection points there".</p> <p>Anyone got an idea for an algorithm? I realize I haven't posted any code and I'm pretty sure that's frowned upon but I have thought about this problem quite a bit. As for <strong>why</strong> I want to do this.. I duno', I'm just curious as to whether it's possible to do this cleanly.</p> <p>Oh, yeah, my AABBs have methods like these that should be useful:</p> <pre><code>Vector&lt;2&gt; getSize () const; Point&lt;2&gt; getCenter () const; //0=Quadrant-1, 1=Quadrant-2, 2=Quadrant-3, 3=Quadrant-4, else, error Point&lt;2&gt; getCorner (int index) const; //0=right, 1=up, 2=left, 3=down, else, error LineSegment2D getSide (int index) const; </code></pre> <p>I could do an ugly hack and just do line-segment &lt;-> line-segment checks but, I duno'.. It feels kinda', well, ugly and inelegant. I'm pretty sure there must be some trickery I could do with the <code>min</code> and <code>max</code> points to do this quickly.</p> <p><img src="https://dl.dropboxusercontent.com/u/86400999/aabbaabbintersection.png" alt="Example"></p>
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    1. USJustin AnyhowStep
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    1. COtype this into a search engine : "check if squares intersect"
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      1. POAABB outline to AABB outline intersection points algorithm?
      1. USMitch Wheat
    2. COI do know how to check for AABB <-> AABB area intersection, containment and outline intersection. I just have trouble getting the exact points of outline intersection where they are, uhh, "well-defined".
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      1. POAABB outline to AABB outline intersection points algorithm?
      1. USJustin AnyhowStep
 

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