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  • Date range intersection in SQL

    - by Will
    I have a table where each row has a start and stop date-time. These can be arbitrarily short or long spans. I want to query the sum duration of the intersection of all rows with two start and stop date-times. How can you do this in MySQL? Or do you have to select the rows that intersect the query start and stop times, then calculate the actual overlap of each row and sum it client-side?

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  • How to Form.GetChildSAtPoint?

    - by serhio
    I would like to obtain the list of controls under a given point. There is a method on System.Windows.Form to obtain a control under a point(GetChildAtPoint) but not point(GetChildsAtPoint). Is there something similar for the list of controls (if borders intersect one other): I need this because I select the objects when user clicks on the panel(I use Microsoft.VisualBasic.PowerPacks.RectangleShape as label bellow). In case if labels are superposed, user should be asked what object to select.

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  • Ensure Oracle row represents a unique timespan

    - by Dan F.
    I have to make a process in Oracle/PLSQL. I have to verify that the interval of time between start_date and end_date from a new row that I create must not intersect other start_dates and end_dates from other rows. Now I need to check each row for that condition and if it doesn't correspond the repetitive instruction should stop and after that to display a message such as "The interval of time given is not correct". I don't know how to make repetitive instructions in Oracle/PLSQL and I would appreciate if you would help me.

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  • Matlab - Find point of intersection between two vectors

    - by Silv3rSurf
    I have a very simple matlab question. What is the easiest way to find the point of intersection between two vectors. I am not familiar with the various matlab fuctions -- it seems like there should be one for this. For example if I have one vector from (0,0) to (6,6) and another vector from (0,6) to (6,0), I need to determine that they intersect at (3,3) Thanks.

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  • How to group by having the same id?

    - by simpatico
    Hello, I want the customerid who bought product X and Y and Z, from the following schema: Sales(customerid, productName, rid); I could do the intersection: select customerid from sales where productName='X' INTERSECT select customerid from sales where productName='X' INTERSTECT select customerid from sales where productName='Z' Is this the best I could do?

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  • Not really a quaestion...but i need help

    - by Dan F.
    I have to make a process in Oracle/PLSQL.....i have to verify that the interval of time between start_date and end_date from a new row that i create must not intersect other start_dates and end_dates from other rows. Now I need to check each row for that condition and if it doesn't correspond the repetitive instruction should stop and after that to display a message such as "The interval of time given is not correct". I don't know how to make repetitive instructions in Oracle/PLSQL and I would appreciate if you would help me.

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  • Outlook rules not working together

    - by JBurace
    I have multiple Outlook (2010) rules and these 2 are having issues together: Rule 1: Apply this rule after the message arrives with blahname in the sender's address and move it to the BlahBox folder. Rule 2: Apply this rule after the message arrives from [email protected] move it to the NoReply folder. If I have rule 1 above rule 2, only rule 1 works (noreply emails stay in the Inbox folder). If I swap and have rule 2 above rule 1, only rule 2 works (blahname emails stay in the Inbox folder). What am I doing wrong; how can I fix this so it applies both rules on incoming email? I'm fairly certain the two rules should never intersect (blahname != domain.com). Also I do not have "this computer only" checked on any rules, I avoid client-only rules.

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  • creating bounding box list

    - by Christian Frantz
    I'm trying to create a list of bounding boxes for each cube drawn, so I can use the boxes to intersect with a ray that my mouse position is casting, but I have no idea how. I've created a list that stores the boxes, but how am I getting the values from each box? for (int x = 0; x < mapHeight; x++) { for (int z = 0; z < mapWidth; z++) { cubes.Add(new Vector3(x, map[x, z], z), Matrix.Identity, grass); boxList.Add(something here); } } public Cube(GraphicsDevice graphicsDevice) { device = graphicsDevice; var vertices = new List<VertexPositionTexture>(); BuildFace(vertices, new Vector3(0, 0, 0), new Vector3(0, 1, 1)); BuildFace(vertices, new Vector3(0, 0, 1), new Vector3(1, 1, 1)); BuildFace(vertices, new Vector3(1, 0, 1), new Vector3(1, 1, 0)); BuildFace(vertices, new Vector3(1, 0, 0), new Vector3(0, 1, 0)); BuildFaceHorizontal(vertices, new Vector3(0, 1, 0), new Vector3(1, 1, 1)); BuildFaceHorizontal(vertices, new Vector3(0, 0, 1), new Vector3(1, 0, 0)); cubeVertexBuffer = new VertexBuffer(device, VertexPositionTexture.VertexDeclaration, vertices.Count, BufferUsage.WriteOnly); cubeVertexBuffer.SetData<VertexPositionTexture>(vertices.ToArray()); } There aren't any clearly defined variables for the bounds of each cube created, so where do I create the bounding box from?

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  • CodeGolf : Find the Unique Paths

    - by st0le
    Here's a pretty simple idea, in this pastebin I've posted some pair of numbers. These represent Nodes of a unidirected connected graph. The input to stdin will be of the form, (they'll be numbers, i'll be using an example here) c d q r a b d e p q so x y means x is connected to y (not viceversa) There are 2 paths in that example. a->b->c->d->e and p->q->r. You need to print all the unique paths from that graph The output should be of the format a->b->c->d->e p->q->r Notes You can assume the numbers are chosen such that one path doesn't intersect the other (one node belongs to one path) The pairs are in random order. They are more than 1 paths, they can be of different lengths. All numbers are less than 1000. If you need more details, please leave a comment. I'll amend as required. Shameless-Plug For those who enjoy Codegolf, please Commit at Area51 for its very own site:) (for those who don't enjoy it, please support it as well, so we'll stay out of your way...)

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  • Implementing Light Volume Front Faces

    - by cubrman
    I recently read an article about light indexed deferred rendering from here: http://code.google.com/p/lightindexed-deferredrender/ It explains its ideas in a clear way, but there was one point that I failed to understand. It in fact is one of the most interesting ones, as it explains how to implement transparency with this approach: Typically when rendering light volumes in deferred rendering, only surfaces that intersect the light volume are marked and lit. This is generally accomplished by a “shadow volume like” technique of rendering back faces – incrementing stencil where depth is greater than – then rendering front faces and only accepting when depth is less than and stencil is not zero. By only rendering front faces where depth is less than, all future lookups by fragments in the forward rendering pass will get all possible lights that could hit the fragment. Can anyone explain how exactly you need to render only front faces? Another question is why do you need the front faces at all? Why can't we simply render all the lights and store the ones that overlap at this pixel in a texture? Does this approach serves as a cut-off plane to discard lights blocked by opaque geometry?

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  • Reacting to rectangle on rectangle collisions

    - by mcjohnalds45
    I don't know how to react to collisions between two axis aligned rectangles that have x, y, width and height values (x and y are from the centre of the box) to make them simply not overlap. I figured I'd just make them move away from each other depending on how far they intersect in the opposite direction (left, right, up or down) of where they collided. If I check for collisions only on the x axis or only on the y axis it works fine, but when checking for both collisions crazy stuff happens. This code executes when the first box collides with the second. It's in lua but feel free to answer in anything that isn't to too counter-intuitive. if box1.x < box2.x then box1.x = box1.x + box2.x - box1.x - (box1.width / 2) - (box2.width / 2) end if box1.x > box2.x then box1.x = box1.x - (box1.x - box2.x - (box1.width / 2) - (box2.width / 2)) end if box1.y < box2.y then box1.y = box1.y + box2.y - box1.y - (box1.height / 2) - (box2.height / 2) end if box1.y > box2.y then box1.y = box1.y - (box1.y - box2.y - (box1.height / 2) - (box2.height / 2)) end

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  • Bounding volume hierarchy - linked nodes (linear model)

    - by teodron
    The scenario A chain of points: (Pi)i=0,N where Pi is linked to its direct neighbours (Pi-1 and Pi+1). The goal: perform efficient collision detection between any two, non-adjacent links: (PiPi+1) vs. (PjPj+1). The question: it's highly recommended in all works treating this subject of collision detection to use a broad phase and to implement it via a bounding volume hierarchy. For a chain made out of Pi nodes, it can look like this: I imagine the big blue sphere to contain all links, the green half of them, the reds a quarter and so on (the picture is not accurate, but it's there to help understand the question). What I do not understand is: How can such a hierarchy speed up computations between segments collision pairs if one has to update it for a deformable linear object such as a chain/wire/etc. each frame? More clearly, what is the actual principle of collision detection broad phases in this particular case/ how can it work when the actual computation of bounding spheres is in itself a time consuming task and has to be done (since the geometry changes) in each frame update? I think I am missing a key point - if we look at the picture where the chain is in a spiral pose, we see that most spheres are already contained within half of others or do intersect them.. it's odd if this is the way it should work.

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  • What to do when TDD tests reveal new functionality that is needed that also needs tests?

    - by Joshua Harris
    What do you do when you are writing a test and you get to the point where you need to make the test pass and you realize that you need an additional piece of functionality that should be separated into its own function? That new function needs to be tested as well, but the TDD cycle says to Make a test fail, make it pass then refactor. If I am on the step where I am trying to make my test pass I'm not supposed to go off and start another failing test to test the new functionality that I need to implement. For example, I am writing a point class that has a function WillCollideWith(LineSegment): public class Point { // Point data and constructor ... public bool CollidesWithLine(LineSegment lineSegment) { Vector PointEndOfMovement = new Vector(Position.X + Velocity.X, Position.Y + Velocity.Y); LineSegment pointPath = new LineSegment(Position, PointEndOfMovement); if (lineSegment.Intersects(pointPath)) return true; return false; } } I was writing a test for CollidesWithLine when I realized that I would need a LineSegment.Intersects(LineSegment) function. But, should I just stop what I am doing on my test cycle to go create this new functionality? That seems to break the "Red, Green, Refactor" principle. Should I just write the code that detects that lineSegments Intersect inside of the CollidesWithLine function and refactor it after it is working? That would work in this case since I can access the data from LineSegment, but what about in cases where that kind of data is private?

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  • Line Intersection from parametric equation

    - by Sidar
    I'm sure this question has been asked before. However, I'm trying to connect the dots by translating an equation on paper into an actual function. I thought It would be interesting to ask here instead on the Math sites (since it's going to be used for games anyway ). Let's say we have our vector equation : x = s + Lr; where x is the resulting vector, s our starting point/vector. L our parameter and r our direction vector. The ( not sure it's called like this, please correct me ) normal equation is : x.n = c; If we substitute our vector equation we get: (s+Lr).n = c. We now need to isolate L which results in L = (c - s.n) / (r.n); L needs to be 0 < L < 1. Meaning it needs to be between 0 and 1. My question: I want to know what L is so if I were to substitute L for both vector equation (or two lines) they should give me the same intersection coordinates. That is if they intersect. But I can't wrap my head around on how to use this for two lines and find the parameter that fits the intersection point. Could someone with a simple example show how I could translate this to a function/method?

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  • Dirt compression from vehicle tires

    - by Mungoid
    So I kinda have this working but its not correct because it just averages, so I wanted to know if anyone here has any ideas. I'm trying to simulate loose dirt compression under the tires of a vehicle to reduce the potential bumpiness of 'chunky' terrain. Currently how I do this is that I have a bounding box shape around my tires, set a little lower so they intersect with the terrain. Each frame, I (currently) average all of the heights of each point in the terrain that are within the box bounds of that tire, and then set them all to that average. Clearly this won't work in most cases because, for example, if i'm on a hill, the terrain will deform way too much. One way I thought was to have a max and min amount the points could raise and lower but that still doesn't seem to work properly and sometimes looks more like steps than smooth dirt. I wanna say that there is probably a bit more to this that what i'm currently doing but I am not sure where to look. Could anyone here shed some light on this subject? Would I benefit any by maybe looking up some smoothing algorith or something similar?

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  • Split up a screen into regions

    - by nexen
    My task: I want to split up a screen into 3 regions for buffs-bar (with picked items), score-info and a game-map. It doesn't matter are regions intersect with each other or not. For example: I have a screen with width=1; height=1 and the origin of coordinates (0;0) is the left bottom point. I have 3 functions: draw items, draw info, draw map. If I use it without any matrix transformations, it draws fullscreen, because it's vertex coordinates are from 0;0 to 1;1. (pseudo-code) drawItems(); drawInfo(); drawMap(); And after that I see only map onto info onto items. My goal: I have some matrixes for transformation vertexes with 0;0-1;1 coordinates to strict regions. There is only one thing, what I need to do - set matrix before drawing. So my call of drawItems-function is like: (pseudo-code) adjustViewMatrixes_andSomethingElse(items.position_of_the_region_there_it_should_be_drawn, items.sizes_of_region_to_draw); setItemsMatrix(); drawItems(); //the same function with vertex coordinates 0;0->1;1, //but it draws in other coordinates, //because I have just set the matrix for region I know only some people will understand me, so there is a picture with regions which I need to make. Every region has 0;0 - 1;1 inner coordinates.

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  • Simple way to implement computer-go board in Java

    - by codingbear
    I want to make a simple Go board to design an Computer Go game. In a go game, you lie a "stone" (white or black) on a position where horizontal and vertical lines intersect. What are some simple ways to restrict users from placing their stones in other locations? Maybe I'm just not seeing a simple solution. EDIT I guess I should rephrase my question better: I want to know how to do the background image of Go board, so that I can lie my stones on the intersection of the horizontal and the vertical lines. I was thinking about getting a just regular Go board image, and when I'm actually rendering stones, I find right position of pixels to lie stones. However, that solution did not seem to be the best solution, since I need to worry about size of stone images and think about proportionality when I either expand or shrink the board window.

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  • Problem with implementing removeAll for List of custom object

    - by Jay
    Hello everyone, I have a scenario in my code where I need to compare two Lists and remove from the first list, objects which are present in the second list. Akin to how the "removeAll" object works for List. Since my List is created on a custom object, the removeAll method won't work for me. I have tried various methods to make this work: - implemented equals() and hashCode for the custom object comprising the list - implemented the Comparable Interface for the custom object - implemented the Comparator Interface for the custom object I've even tried using the Apache Common's CollectionUtils and ListUtils methods (subtract, intersect, removeAll). None seem to work. I understand I will perhaps need to write some custom removal code. But not sure how to go about doing that. Any pointers helping me move in the right direction will be really appreciated. Thanks, Jay

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  • good methods for boolean operations on overlapping polygons

    - by BenjaminGolder
    What is the best open source library for performing boolean operations (union, intersect, subtract) on shapefiles? What do you like to use? OGR looks like it probably has this capability, though I'm having trouble finding the particular commands in their documentation. Shapely definitely does this, and is easy to understand. PostGIS appears to also have some commands for this. But there must be more, and I'm having trouble finding them. I don't have much experience with any of the, and would appreciate any opinions on these or other libraries. Thanks!

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  • Blending Three Images into Graphics Context Using Alpha Blend Mode kBlendModeOverlay

    - by steganous
    Does kCGBlendModeOverlay not work exactly like Photoshop's Overlay blending mode? I'm trying to overlay three images into a graphic context via: [uiimageGreen drawAtPoint:CGPointMake(x, y) blendMode:kCGBlendModeOverlay alpha:1.0]; [uiimageRed drawAtPoint:CGPointMake(x, y) blendMode:kCGBlendModeOverlay alpha:1.0]; [uiimageBlue drawAtPoint:CGPointMake(x, y) blendMode:kCGBlendModeOverlay alpha:1.0]; In the end, if I overlay just two of the three, the result is much closer to my desired output color in places where both images intersect. Adding the third image, however, causes the first-drawn image's color to be dominant in the resulting mix of colors. (e.g. in the above code, green comes out dominant, when the result should actually be white) Do you get the same result if you try?

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  • Setting the background colour/highlight colour for a given string range using Core Text

    - by Jasarien
    I have some text laid out using Core Text in my iPhone app. I'm using NSAttributedString to set certain styles within the text for given ranges. I can't seem to find an attribute for setting a background / highlight colour, though it would seem it is possible. I couldn't find an attribute name constant that sounded relevant and the documentation only lists: kCTCharacterShapeAttributeName kCTFontAttributeName kCTKernAttributeName kCTLigatureAttributeName kCTForegroundColorAttributeName kCTForegroundColorFromContextAttributeName kCTParagraphStyleAttributeName kCTStrokeWidthAttributeName kCTStrokeColorAttributeName kCTSuperscriptAttributeName kCTUnderlineColorAttributeName kCTUnderlineStyleAttributeName kCTVerticalFormsAttributeName kCTGlyphInfoAttributeName kCTRunDelegateAttributeName Craig Hockenberry, developer of Twitterrific has said publicly on Twitter that he uses Core Text to render the tweets, and Twitterrific has this background / highlight that I'm talking about when you touch a link. Any help or pointers in the right direction would be fantastic, thanks. Edit: Here's a link to the tweet Craig posted mentioning "Core text, attributed strings and a lot of hard work", and the follow up that mentioned using CTFrameSetter metrics to work out if touches intersect with links.

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  • What are appropriate ways to represent relationships between people in a database table?

    - by Emilio
    I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "replace" Tony and Bob might "be an employee of" Rob and Bob might also "be married to" Mary. What's the best way to represent this in the database? A many to many intersect table? A series of self joins? A relationship table with one row per relationship pair and type, where I insert records for the relationship in both directions?

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  • Intersecting boundaries with lucene

    - by Silvio Donnini
    I'm using Lucene, and I'm trying to find a way to index and retrieve documents that have a ranged property. For example I have: Document 1: Price:[30 TO 50] Document 2: Price:[45 TO 60] Document 3: Price:[60 TO 70] And I would like to search for all the documents whose ranges intersect a specific interval, in the above example, if I search for Price in [55 TO 65] I should get Document 2 and Document 3 as results. I don't think NumericRangeQueries alone would do the trick, I need to work on the index with something similar to R-trees, but are they implemented in Lucene? Also, I suppose that what I need should be a subclass of MultiTermQuery, because the query Price in [55 TO 65] has two boundaries, but I don't see anything suitable among MultiTermQuery's subclasses. Any help is appreciated, thanks, Silvio P.S. I'm using Lucene 2.9.0, but I can update to the latest release if needed.

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  • Spatial Index for Rectangles With Fast Insert

    - by TheCloudlessSky
    Hello, I'm looking for a data structure that provides indexing for Rectangles. I need the insert algorithm to be as fast as possible since the rectangles will be moving around the screen (think of dragging a rectangle with your mouse to a new position). I've looked into R-Trees, R+Trees, kD-Trees, Quad-Trees and B-Trees but from my understanding insert's are usually slow. I'd prefer to have inserts at sub-linear time complexity so maybe someone can prove me wrong about either of the listed data structures. I should be able to query the data structure for what rectangles are at point(x, y) or what rectangles intersect rectangle(x, y, width, height). EDIT: The reason I want insert so fast is because if you think of a rectangle being moved around the screen, they're going to have to be removed and then re-inserted. Thanks!

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