collision

Could this cause multiple identical GUIDs?

由 别等时光非礼了梦想. 提交于 2019-12-01 16:18:39
As GUID generation is time-dependent, if System.Guid.NewGuid() is called multiple times at the exact same instant on different threads, could it return identical GUIDs? George V. Reilly On Windows, GUIDs (UUIDs) are created from a cryptographic random number generator with UuidCreate . They are version 4 UUIDs in terms of RFC 4122 . No timestamps or ethernet cards are involved, unless you're using old school version 1 GUIDs created with UuidCreateSequential . See also How Random is System.Guid.NewGuid()? (Take two) No, there is a serial number inside it that changes for each call, so multiple

Could this cause multiple identical GUIDs?

由 自作多情 提交于 2019-12-01 15:08:29
问题 As GUID generation is time-dependent, if System.Guid.NewGuid() is called multiple times at the exact same instant on different threads, could it return identical GUIDs? 回答1: On Windows, GUIDs (UUIDs) are created from a cryptographic random number generator with UuidCreate. They are version 4 UUIDs in terms of RFC 4122. No timestamps or ethernet cards are involved, unless you're using old school version 1 GUIDs created with UuidCreateSequential. See also How Random is System.Guid.NewGuid()?

Collision of Two Circles

由 ▼魔方 西西 提交于 2019-12-01 13:34:36
问题 Hey i am writing a program in java (but i think thats not that relevant for this question), where two robots (circles) are driving arround. A robot is driving with a certain speed from a certain location to a certain location. Problem is how to determine if the circles having a collision. I cant use the midPoint of the circle and the vector its moving, cause the circle have a radius. Another problem is I just can't check the final locations of the circles. I need to check if the collide on

Collision Detection/Remove object from ArrayList

由 一世执手 提交于 2019-12-01 12:42:51
问题 I am currently trying to test collision between a falling object and a box. I understand basic collision detection, but my problem here is that I have to test it for an indefinite number of falling objects. When these objects(blossoms) are created, they are stored in an ArrayList. The ArrayList handles the drawing of the object on the canvas (using a for each to update the position). My problem comes when a blossom is "caught" in the box. How do I make it disappear from the screen/removed

Collision detection : rounded object

由 给你一囗甜甜゛ 提交于 2019-12-01 09:20:01
问题 I'm developing a Java game (but the dev. language doesn't really matter) including rounded objects like balls or pucks, and now working on collisions. I use a timer, so on every frame I check if a collision happens. Here is a graph that represents the top-right piece of an object. The center of the object is represented by the point [0,0], its radius is 10px and the units are pixels. Now if my object (for example, obj_1 ) is square/diamond-shaped (blue line), to find if another one ( obj_2 )

html5 canvas elastic collision squares

由 假如想象 提交于 2019-12-01 08:31:06
I am re-asking this question since I did not make myself clear in what I wanted in my last question. Does anyone know how to do elastic collision or handle collision in Canvas using rectangles? Or can point me in the right direction? I created a canvas that has multiple square and would like each square to deflect when they touch. Here is a quick fiddle that I put together showing to black buffer canvases http://jsfiddle.net/claireC/Y7MFq/10/ line 39 is where I started the collision detection and line 59 is where I tried to execute it. I will have more than 3 squares moving around and want

Javascript - Circle-Circle Collision Issue

由 自作多情 提交于 2019-12-01 08:04:41
问题 I am making a game in HTML5, Canvas, and this is my code for resolving collision between two moving circles: function resCCCol(a, b) { var dx = a.x - b.x; var dy = a.y - b.y; var dist = dx * dx + dy * dy; var vx = b.vx - a.vx; var vy = b.vy - a.vy; var dot = dx * vx + dy * vy; if (dot > 0) { var scale = dot / dist; var cx = dx * scale; var cy = dy * scale; var mass = a.r + b.r; var cw1 = 2 * b.r / mass; var cw2 = 2 * a.r / mass; a.vx += cw1 * cx a.vy += cw1 * cy b.vx -= cw2 * cx b.vy -= cw2 *

Hash and salt collision

由 南楼画角 提交于 2019-12-01 06:36:46
I remember a guy telling me that if I let him change 4 bytes he can make a file have any checksum he wants ( CRC-32 ). I heard mention of salting a hash. I am wondering if someone had his file match my file would salting the MD5 or SHA-1 hash change the result so both files no longer collide? Or does it change the end hash value only? You are mixing up two different uses of hash values: Checksumming for guarding against random (non-malicious) errors. Computing cryptographical message digests for storing passwords, signing messages, certificates ... CRCs are a good choice for the first

Hash and salt collision

由 為{幸葍}努か 提交于 2019-12-01 05:35:38
问题 I remember a guy telling me that if I let him change 4 bytes he can make a file have any checksum he wants (CRC-32). I heard mention of salting a hash. I am wondering if someone had his file match my file would salting the MD5 or SHA-1 hash change the result so both files no longer collide? Or does it change the end hash value only? 回答1: You are mixing up two different uses of hash values: Checksumming for guarding against random (non-malicious) errors. Computing cryptographical message

New velocity after circle collision

由 余生长醉 提交于 2019-11-30 23:08:46
On a circular billiard-table, the billiard-ball collides with the boundary of that table with some velocity v1. This collision is detected as follows: double s = sqrt( (p.x-a)*(p.x-a) + (p.y-b)*(p.y-b) ); if (s<r) // point lies inside circle // do nothing else if (s==r) // point lies on circle // calculate new velocity else if (s>r) // point lies outside circle // move point back onto circle (I already have that part) // calculate new velocity Now how can the new velocity v2 after the collision be calculated, such that angle of incidence = angle of reflection (elastic collision)? PS: The
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