Your quadtree structure isn’t optimal. You’re right to store 4 subtrees per node, but actual objects should only be stored inside the leaves, not inner nodes. Therefore the collection holding the actual objects needs to be moved to the leaves. Let’s have a look at the implementation of the operations: Insert an object into the … Read more
Duplicate of Expected collisions for perfect 32bit crc The answer referenced this article: http://arstechnica.com/civis/viewtopic.php?f=20&t=149670 Found the image below from: http://preshing.com/20110504/hash-collision-probabilities
As of today, AngularJS modules do not provide any sort of namespacing that would prevent collisions between objects in different modules. The reason is that an AngularJS app has a single injector that holds names for all objects without respect to module names. The AngularJS Developer Guide says: To manage the responsibility of dependency creation, … Read more
Why don’t you use a long variant of the default String.hashCode() (where some really smart guys certainly put effort into making it efficient – not mentioning the thousands of developer eyes that already looked at this code)? // adapted from String.hashCode() public static long hash(String string) { long h = 1125899906842597L; // prime int len … Read more
At least in the case of static libraries you can work around it quite conveniently. Consider those headers of libraries foo and bar. For the sake of this tutorial I’ll also give you the source files examples/ex01/foo.h int spam(void); double eggs(void); examples/ex01/foo.c (this may be opaque/not available) int the_spams; double the_eggs; int spam() { return … Read more
Efficient Quadtrees All right, I’ll take a shot at this. First a teaser to show the results of what I’ll propose involving 20,000 agents (just something I whipped up real quick for this specific question): The GIF has extremely reduced frame rate and significantly lower res to fit the 2 MB maximum for this site. … Read more
My best guess is that Math.random() is broken on your system for some reason (bizarre as that sounds). This is the first report I’ve seen of anyone getting collisions. node-uuid has a test harness that you can use to test the distribution of hex digits in that code. If that looks okay then it’s not … Read more
Yes, you can. Since GUIDs are 128 bits long, there is admittedly a minute possibility of a clash—but the word “minute” is nowhere near strong enough. There are so many GUIDs that if you generate several trillion of them randomly, you’re still more likely to get hit by a meteorite than to have even one … Read more
Your error comes from this line initially: var direction1 = Math.atan2(ball1.velocitY, ball1.velocityX); You have ball1.velocitY (which is undefined) instead of ball1.velocityY. So Math.atan2 is giving you NaN, and that NaN value is propagating through all your calculations. This is not the source of your error, but there is something else that you might want to … Read more
According to the documentation, the static method UUID.randomUUID() generates a type 4 UUID. This means that six bits are used for some type information and the remaining 122 bits are assigned randomly. The six non-random bits are distributed with four in the most significant half of the UUID and two in the least significant half. … Read more