There’s no one answer to this but large worlds are often space-partitioned by using something along the lines of a quadtree or kd-tree which brings search times for finding nearest neighbors below linear time (fractional power, or at worst O( N^(2/3) ) for a 3D game). These methods are often referred to as BSP for … Read more
AABB stands for “Axis-Aligned Bounding Box.” It is a fairly computationally- and memory-efficient way of representing a volume, typically used to see if two objects might be touching. Since it is axis-aligned, it does not necessarily “fit” your real 3D object very well. AABB checks are often used as a coarse first-approximation to see if … Read more
In Three.js, the utilities CollisionUtils.js and Collisions.js no longer seem to be supported, and mrdoob (creator of three.js) himself recommends updating to the most recent version of three.js and use the Ray class for this purpose instead. What follows is one way to go about it. The idea is this: let’s say that we want … Read more
var overlaps = (function () { function getPositions( elem ) { var pos, width, height; pos = $( elem ).position(); width = $( elem ).width(); height = $( elem ).height(); return [ [ pos.left, pos.left + width ], [ pos.top, pos.top + height ] ]; } function comparePositions( p1, p2 ) { var r1, r2; … Read more
Hash tables deal with collisions in one of two ways. Option 1: By having each bucket contain a linked list of elements that are hashed to that bucket. This is why a bad hash function can make lookups in hash tables very slow. Option 2: If the hash table entries are all full then the … Read more
Swift 4 let view = … let point = … view.bounds.contains(point) Objective-C Use CGRectContainsPoint(): bool CGRectContainsPoint(CGRect rect, CGPoint point); Parameters rect The rectangle to examine. point The point to examine. Return Value true if the rectangle is not null or empty and the point is located within the rectangle; otherwise, false. A point is considered … Read more
Taking E is the starting point of the ray, L is the end point of the ray, C is the center of sphere you’re testing against r is the radius of that sphere Compute: d = L – E ( Direction vector of ray, from start to end ) f = E – C ( … Read more
Here is how I would do it: bool intersects(CircleType circle, RectType rect) { circleDistance.x = abs(circle.x – rect.x); circleDistance.y = abs(circle.y – rect.y); if (circleDistance.x > (rect.width/2 + circle.r)) { return false; } if (circleDistance.y > (rect.height/2 + circle.r)) { return false; } if (circleDistance.x <= (rect.width/2)) { return true; } if (circleDistance.y <= (rect.height/2)) … Read more
To detect whether two balls collide, just check whether the distance between their centers is less than two times the radius. To do a perfectly elastic collision between the balls, you only need to worry about the component of the velocity that is in the direction of the collision. The other component (tangent to the … Read more
For graphics, I’d rather not prefer integers. Many systems use integers for UI painting (pixels are ints after all), but macOS, for example, uses float for everything. macOS only knows points and a point can translate to one pixel, but depending on monitor resolution, it might translate to something else. On retina screens half a … Read more