collision | 易学教程

MD5 collision for known input

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问题 Is it possible to create a MD5 collision based on a known input value? So for example I have input string abc with MD5 900150983cd24fb0d6963f7d28e17f72 . Now I want to add bytes to string def to get the same MD5 900150983cd24fb0d6963f7d28e17f72 . (I know this is possible by bruteforcing and waiting a long time; I want to know if there is a more efficient way in doing this) 回答1: Unitl now no algorithm has been discovered that allows you to find a matching input that will generate a given md5

Finding the intersection of two 3D polygons

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问题 a.k.a. Polygon clipping algorithm in 3D a.k.a. Finding the collision manifold between 2 colliding polygons Most algorithms for polygon clipping are described in detail for 2D and described as being extendable to 3D but without details. For example the sutherland-hodgman clipping algorithm Having been unable to find any 3D implementations or pseudo code on the internet I am now asking here (and attempting to answer my own question) The algorithm would take two shapes such as those shown below:

Issue with Terrain Collision using Three.js

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I have created a terrain via a heightmap in Three.js and am using mrdoob's misc_controls_pointerlock for collision and movement. However, when I do objects.push(terrainobj); the performance goes down to about 3fps (from around 60) and there is no collision with the terrain. The collision is achieved via rays. How can I get around this? If it's just a heightmap you could avoid using ray and do the collision checking right in the bitmap (using canvas and imagedata). You just need to convert your XZ world position to the XY pixel in the heightmap. Then, if your Y position in the world is lower

Collision Normal of two points

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I'm trying to calculate the collision normal of two points. I need this for the collision response equations to calculate the new angular and linear velocities. This scenario happens when, for example, the corners of two 2d or 3d boxes collide with each other. What would be their collision normal? I now that in the case of a vertex and face collision the collision normal would be just the normal of the face. It is undefined. Technically, the collision normal should be the normal at the surface of the their configuration space obstacle (ie the set of all transformations where the two objects

Java hashtable with separate chaining collision resolution?

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I have created a program using the built in java.util.hashtable but now I need to resolve collisions using separate chaining. Is it possible with this implementation of a hashtable? Is there one out there already implemented that uses separate chaining? Looking at the source of the Hashtable implementation, it looks like it already uses separate chaining. If you look at the Entry<K,V> class starting at line 901, you'll see that it has a reference to another Entry named next . If you then look at the put() method, on line 420 the next reference is populated via the constructor to be whatever

Detecting collision, during a CAKeyFrameAnimation

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Is it possible to detect the collision of two UIImageViews while one is travelling along a path during a CAKeyFrameAnimation? If so how is this done, I have tried multiple methods including checking both the CGRects for collision during the animation - but can't find a suitable method for performing a method during a CAKeyFrameAnimation and trying to detect collision of the path and the UIImageView. You need to get the properties from the presentation layer. It will have the best approximation of information that exists during animation. Access it by view.layer.presentationLayer Look at the

Time Corrected Verlet Integration and too big timesteps

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问题 i use a Time Corrected Verlet Integration found here: http://www.gamedev.net/page/resources/_/technical/math-and-physics/a-simple-time-corrected-verlet-integration-method-r2200 But when my ball is on a wall (horizontal wall, ball upon it and the acceleration is directed down) for a some time, my game cannot recognize the collision in the right way and the ball goes down. If I put a fixed cap to deltatime like 1/60 it seems to work. I think the problem are too big timesteps. But the time

Solving a cubic to find nearest point on a curve to a point

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问题 Ok, I have a projectile that has its position defined such that: a.x = initialX + initialDX * time; a.y = initialY + initialDY * time + 0.5 * gravtiy * time^2; I want to be able to predict which obstacles in my environment this projectile will collide with. I plan on checking the distance from A the closest point on the curve to the point P . I figure that at the point A the tangent to the curve will be perpendicular to the vector AP , and that the tangent to the curve at A will simply be the

jquery .animate() collision detection

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I'm using animate to move a div within a grid of divs. As a test I am setting some of the grid divs as obstacles. If the animated div collides with one of the obstacles I want to end the animation. A plug in is fine or a snippet of code. I kind of suspect I am sniffing up the wrong tree with .animate() so any shove in the right direction or improvement on what I am doing is appreciated: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html lang="en"> <head> <meta charset="utf-8"> <title>Game Test</title> <!-- meta tags -

Buggy bouncing balls

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I was making a colliding ball sketch in Processing, and I encountered a weird bug. Despite having a condition for bouncing off of the walls, some balls get stuck to it . I can't find the source of error here. Can someone help? I also realise that there maybe few (a lot) bad coding practices, but I apologise beforehand. I am posting the codes below. 1) Main : https://pastebin.com/hv0H14gZ particle[] elec = new particle[5]; boolean record = false; void setup(){ float x=0,y=0; int i,j; float diam = 100; size(800,400); //Initialising the particle objects for (int k = 0; k < elec.length; k++){ x =