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  • How to change handedness of coordinates?

    - by 742
    How to convert from Euler's coordinates E1 = (x1, y1, z1, yaw1, pitch1, roll1) to E2 = (x2, y2, z2, yaw2, pitch2, roll2) where x, y, z are the coordinates of a point and yaw, pitch, roll the direction/orientation of a vector which origin is the point. yaw is around y, pitch around x, roll around z. They are performed in that order. Yaw 0 is normal to the plan xy (opposite to z in E1 and equal to z in E2). E1 uses a right handed space and E2 a left handed space. Both have the same origin, the same direction for y (top) and z (into the screen). They differ by x which is to the left on E1 and to the right on E2. They also differ by their direction of positive rotations. I've a custom type to hold the scalar representation and to convert from and to the equivalent WPF Matrix3d representation.

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  • Templated Control databinding to custom properties

    - by Dan Wray
    Is there some trick that I'm missing here? I've created a templated control, very simple. One single property on it, and I'd like to databind from the (viewmodel/datacontext of the) page in which it's hosted to a custom property on the control. The property will eventually be a vector type object, defining the position of the control, however in an attempt to get this to work I've tried reducing it to a basic string property. Each time I'm faced with "Set property 'SimpleGame.Classes.Sprite.Property' threw an exception.". I can't even catch the exception in a debug session, the set property code is not being executed. Do I need to use a dependency / attached property or something? I wouldn't have thought so...

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  • Could the assign function for containers possibly overflow?

    - by Kristo
    I ran into this question today and thought I should post it for the community's reference and/or opinions. The standard C++ containers vector, deque, list, and string provide an assign member function. There are two versions; I'm primarily interested in the one accepting an iterator range. The Josuttis book is a little ambiguous with its description. From p. 237... Assigns all elements of the range [beg,end); this is, is replaces all existing elements with copies of the elements of [beg,end). It doesn't say what happens if the size of the assignee container is different from the range being assigned. Does it truncate? Does it automagically expand? Is it undefined behavior?

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  • How do you calculate the reflex angle given to vectors in 3D space?

    - by Reimund
    I want to calculate the angle between two vectors a and b. Lets assume these are at the origin. This can be done with theta = arccos(a . b / |a| * |b|) However arccos gives you the angle in [0, pi], i.e. it will never give you an angle greater than 180 degrees, which is what I want. So how do you find out when the vectors have gone past the 180 degree mark? In 2D I would simply let the sign of the y-component on one of the vectors determine what quadrant the vector is in. But what is the easiest way to do it in 3D?

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  • Masks and transparency

    - by Henrik
    Hi, I'm fairly new to Shoes and ran into two problems. First I want to set a mask using a partially transparent png, like this: mask do image "images/stencilMask.png" end Is this possible somehow or can only vector shapes be used? Apart from that, I noticed a small bug(?) when trying to set a transparent color as a stroke on any kind of text, like this: title "Hello", :stroke => rgb(1.0, 0.0, 0.0, 0.5) The transparency simply isn't applied. Am I doing anything wrong, or is this actually a bug? Cheers and thanks for all answers

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  • Min/Max across an array of objects

    - by graham.reeds
    It has been done to death pretty much, here on SO and around the 'Net. However I was wondering if there was a way to leverage the standard min/max functions of: Array.max = function(array) { return Math.max.apply(Math, array); }; Array.min = function(array) { return Math.min.apply(Math, array); }; So I can search across an array of objects of say: function Vector(x, y, z) { this.x = x; this.y = y; this.z = z; } var ArrayVector = [ /* lots of data */ ]; var min_x = ArrayVector.x.min(); // or var max_y = ArrayVector["y"].max(); Currently I have to loop through the array and compare the object values manually and craft each one to the particular need of the loop. A more general purpose way would be nice (if slightly slower).

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  • Vim OmniCppComplete on vectors of pointers

    - by Alex
    Hi, I might have done something wrong in the set up but is OmniCppComplete supposed to provide the members/functions of classes when doing this? vectorofpointers[0]-> At the moment all I get when trying that are things relating to the vector class itself, which obviously isn't very useful. I think it might have been working before I tagged /usr/include/ but I could be wrong. Also, is it possible to disable the preview window? I find it just clutters up my workspace. And since I enabled ShowPrototypeInAbbr I don't really need it. Thanks, Alex

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  • Coordinate geometry operations in images/discrete space

    - by avd
    I have images which have line segments, rays etc. I am representing these line segments using Bresenham algorithm (means whatever coordinates I get using this algorithm between two points). Now I want to do operations such as finding intersection point between two line segments, finding the projection of one vector onto other etc... The problem is I am not working in continuous space. The line segments are being approximated using Bresenham algorithm. So I want suggestions on what are the best and most efficient ways to do this? A link to C++ library or implementation would also be good enough. Please suggest some books which deal with such problems.

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  • Building resultset using collection object

    - by Bhaskara Krishna Mohan Potam
    Hi, I had an issue in building the resultset using java. Here it goes... I am storing a collection object which is organized as row wise taken from a resultset object and putting the collection object(which is stored as vector/array list) in cache and trying to retrieve the same collection object. Here i need to build back the resultset again using the collection object. Now my doubt is building the resultset in this way possible or not? Please let me know asap. Thanks in advance, Bhaskar

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  • C++: building iterator from bits

    - by gruszczy
    I have a bitmap and would like to return an iterator of positions of set bits. Right now I just walk the whole bitmap and if bit is set, then I provide next position. I believe this could be done more effectively: for example build statically array for each combination of bits in single byte and return vector of positions. This can't be done for a whole int, because array would be too big. But maybe there are some better solutions? Do you know any smart algorithms for this?

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  • How to generate a lower frequency version of a signal in Matlab?

    - by estourodepilha.com
    With a sine input, I tried to modify it's frequency cutting some lower frequencies in the spectrum, shifting the main frequency towards zero. As the signal is not fftshifted I tried to do that by eliminating some samples at the begin and at the end of the fft vector: interval = 1; samplingFrequency = 44100; signalFrequency = 440; sampleDuration = 1 / samplingFrequency; timespan = 1 : sampleDuration : (1 + interval); original = sin(2 * pi * signalFrequency * timespan); fourierTransform = fft(original); frequencyCut = 10; %% Hertz frequencyCut = floor(frequencyCut * (length(pattern) / samplingFrequency) / 4); %% Samples maxFrequency = length(fourierTransform) - (2 * frequencyCut); signal = ifft(fourierTransform(frequencyCut + 1:maxFrequency), 'symmetric'); But it didn't work as expected. I also tried to remove the center part of the spectrum, but it wielded a higher frequency sine wave too. How to make it right?

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  • C++ min heap with user-defined type.

    - by bsg
    Hi, I am trying to implement a min heap in c++ for a struct type that I created. I created a vector of the type, but it crashed when I used make_heap on it, which is understandable because it doesn't know how to compare the items in the heap. How do I create a min-heap (that is, the top element is always the smallest one in the heap) for a struct type? The struct is below: struct DOC{ int docid; double rank; }; I want to compare the DOC structures using the rank member. How would I do this? I tried using a priority queue with a comparator class, but that also crashed, and it also seems silly to use a data structure which uses a heap as its underlying basis when what I really need is a heap anyway. Thank you very much, bsg

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  • Help understanding some OpenGL stuff

    - by shinjuo
    I am working with some code to create a triangle that moves with arrow keys. I want to create a second object that moves independently. This is where I am having trouble, I have created the second actor, but cannot get it to move. There is too much code to post it all so I will just post a little and see if anyone can help at all. ogl_test.cpp #include "platform.h" #include "srt/scheduler.h" #include "model.h" #include "controller.h" #include "model_module.h" #include "graphics_module.h" class blob : public actor { public: blob(float x, float y) : actor(math::vector2f(x, y)) { } void render() { transform(); glBegin(GL_TRIANGLES); glVertex3f(0.25f, 0.0f, -5.0f); glVertex3f(-.5f, 0.25f, -5.0f); glVertex3f(-.5f, -0.25f, -5.0f); glEnd(); end_transform(); } void update(controller& c, float dt) { if (c.left_key) { rho += pi / 9.0f * dt; c.left_key = false; } if (c.right_key) { rho -= pi / 9.0f * dt; c.right_key = false; } if (c.up_key) { v += .1f * dt; c.up_key = false; } if (c.down_key) { v -= .1f * dt; if (v < 0.0) { v = 0.0; } c.down_key = false; } actor::update(c, dt); } }; class enemyOne : public actor { public: enemyOne(float x, float y) : actor(math::vector2f(x, y)) { } void render() { transform(); glBegin(GL_TRIANGLES); glVertex3f(0.25f, 0.0f, -5.0f); glVertex3f(-.5f, 0.25f, -5.0f); glVertex3f(-.5f, -0.25f, -5.0f); glEnd(); end_transform(); } void update(controller& c, float dt) { if (c.left_key) { rho += pi / 9.0f * dt; c.left_key = false; } if (c.right_key) { rho -= pi / 9.0f * dt; c.right_key = false; } if (c.up_key) { v += .1f * dt; c.up_key = false; } if (c.down_key) { v -= .1f * dt; if (v < 0.0) { v = 0.0; } c.down_key = false; } actor::update(c, dt); } }; int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, char* lpCmdLine, int nCmdShow ) { model m; controller control(m); srt::scheduler scheduler(33); srt::frame* model_frame = new srt::frame(scheduler.timer(), 0, 1, 2); srt::frame* render_frame = new srt::frame(scheduler.timer(), 1, 1, 2); model_frame->add(new model_module(m, control)); render_frame->add(new graphics_module(m)); scheduler.add(model_frame); scheduler.add(render_frame); blob* prime = new blob(0.0f, 0.0f); m.add(prime); m.set_prime(prime); enemyOne* primeTwo = new enemyOne(2.0f, 0.0f); m.add(primeTwo); m.set_prime(primeTwo); scheduler.start(); control.start(); return 0; } model.h #include <vector> #include "vec.h" const double pi = 3.14159265358979323; class controller; using math::vector2f; class actor { public: vector2f P; float theta; float v; float rho; actor(const vector2f& init_location) : P(init_location), rho(0.0), v(0.0), theta(0.0) { } virtual void render() = 0; virtual void update(controller&, float dt) { float v1 = v; float theta1 = theta + rho * dt; vector2f P1 = P + v1 * vector2f(cos(theta1), sin(theta1)); if (P1.x < -4.5f || P1.x > 4.5f) { P1.x = -P1.x; } if (P1.y < -4.5f || P1.y > 4.5f) { P1.y = -P1.y; } v = v1; theta = theta1; P = P1; } protected: void transform() { glPushMatrix(); glTranslatef(P.x, P.y, 0.0f); glRotatef(theta * 180.0f / pi, 0.0f, 0.0f, 1.0f); //Rotate about the z-axis } void end_transform() { glPopMatrix(); } }; class model { private: typedef std::vector<actor*> actor_vector; actor_vector actors; public: actor* _prime; model() { } void add(actor* a) { actors.push_back(a); } void set_prime(actor* a) { _prime = a; } void update(controller& control, float dt) { for (actor_vector::iterator i = actors.begin(); i != actors.end(); ++i) { (*i)->update(control, dt); } } void render() { for (actor_vector::iterator i = actors.begin(); i != actors.end(); ++i) { (*i)->render(); } } };

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  • (External) Java library for creating Tree structure ?

    - by suVasH.....
    I am planning to implement a tree structure where every node has two children and a parent along with various other node properties (and I'd want to do this in Java ) Now, the way to it probably is to create the node such that it links to other nodes ( linked list trick ), but I was wondering if there is any good external library to handle all this low level stuff. ( for eg. the ease of stl::vector vs array in C++ ). I've heard of JDots, but still since i haven't started (and haven't programmed a lot in Java), I'd rather hear out before I begin.

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  • What is the right approach when using STL container for median calculation?

    - by sharkin
    Let's say I need to retrieve the median from a sequence of 1000000 random numeric values. If using anything but STL::list, I have no (built-in) way to sort sequence for median calculation. If using STL::list, I can't randomly access values to retrieve middle (median) of sorted sequence. Is it better to implement sorting myself and go with e.g. STL::vector, or is it better to use STL::list and use STL::list::iterator to for-loop-walk to the median value? The latter seems less overheadish, but also feels more ugly.. Or are there more and better alternatives for me?

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  • Rotation towards an object in 3d space

    - by retoucher
    hello, i have two coordinates on a 2d plane in 3d space, and am trying to rotate one coordinate (a vector) to face the other coordinate. my vertical axis is the y-axis, so if both of the coordinates are located flat on the 2d plane, they would both have a y-axis of 0, and their x and z coordinates determine their position length/width-wise on the plane. right now, i'm calculating the angle like so (language agnostic): angle = atan2(z2-z1,x2-x1); and am rotating/translating in space like so: pushMatrix(); rotateY(angle); popMatrix(); this doesn't seem to be working though. are my calculations/process correct?

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  • Qt drag & drop button; drop not detecting

    - by Thomas Verbeke
    I'm creating a 2D game in QT and i'm trying to implement a drag & drop into my program. For some reason the drop is not registered: qDebug should print a message on dropping but this doesn't happen. #include "dialog.h" #include "ui_dialog.h" #include "world.h" #include <vector> Dialog::Dialog(QWidget *parent) : QDialog(parent), ui(new Ui::Dialog) { ui->setupUi(this); scene = new QGraphicsScene(this); ui->graphicsView->setScene(scene); MySquare *item; QGraphicsRectItem *enemyItem; World *myWorld = new World(); std::vector<Tile*> tiles = myWorld->createWorld(":/texture.jpg"); int count = 0; foreach (Tile *tile, tiles){ count++; item = new MySquare(tile->getXPos()*4,tile->getYPos()*4,4,4); item->setBrush(QColor(tile->getValue()*255,tile->getValue()*255,tile->getValue()*255)); item->setAcceptDrops(true); scene->addItem(item); } player = new MySquare(10,20,10,10); player->setAcceptDrops(true); scene->addItem(player); //drag & drop part QPushButton *pushButton = new QPushButton("Click Me",this); connect(pushButton,SIGNAL(pressed()),this,SLOT(makeDrag())); setAcceptDrops(true); } void Dialog::makeDrag() { QDrag *dr = new QDrag(this); // The data to be transferred by the drag and drop operation is contained in a QMimeData object QMimeData *data = new QMimeData; data->setText("This is a test"); // Assign ownership of the QMimeData object to the QDrag object. dr->setMimeData(data); // Start the drag and drop operation dr->start(); } mysquare.cpp #include "mysquare.h" MySquare::MySquare(int _x,int _y, int _w, int _h) { isPlayer=false; Pressed=false; setFlag(ItemIsMovable); setFlag(ItemIsFocusable); setAcceptDrops(true); color=Qt::red; color_pressed = Qt::green; x = _x; y = _y; w = _w; h = _h; } QRectF MySquare::boundingRect() const { return QRectF(x,y,w,h); } void MySquare::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { QRectF rec = boundingRect(); QBrush brush(color); if (Pressed){ brush.setColor(color); } else { brush.setColor(color_pressed); } painter->fillRect(rec,brush); painter->drawRect(rec); } void MySquare::mousePressEvent(QGraphicsSceneMouseEvent *event) { Pressed=true; update(); QGraphicsItem::mousePressEvent(event); qDebug() << "mouse Pressed"; } void MySquare::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) { Pressed=false; update(); QGraphicsItem::mousePressEvent(event); qDebug() << "mouse Released"; } void MySquare::keyPressEvent(QKeyEvent *event){ int x = pos().x(); int y = pos().y(); //key handling QGraphicsItem::keyPressEvent(event); } void MySquare::dropEvent(QDropEvent *event) { qDebug("dropEvent - square"); // Unpack dropped data and handle it the way you want qDebug("Contents: %s", event->mimeData()->text().toLatin1().data()); } void MySquare::dragMoveEvent(QDragMoveEvent *event){ qDebug("dragMoveEvent - square "); event->accept(); } void MySquare::dragEnterEvent(QDragEnterEvent *event){ event->setAccepted(true); qDebug("dragEnterEvent - square"); event->acceptProposedAction(); } void MySquare::setBrush(QColor _color){ color = _color; color_pressed = _color; update(); //repaint } edit; there is no problem with qDebug() i'm just using it to test them i'm inside the drag events..which i'm not

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  • Python KMeans clustering words

    - by sadawd
    Dear Everyone I am interested to perform kmeans clustering on a list of words with the distance measure being Leveshtein. 1) I know there are a lot of frameworks out there, including scipy and orange that has a kmeans implementation. However they all require some sort of vector as the data which doesn't really fit me. 2) I need a good clustering implementation. I looked at python-clustering and realize that it doesn't a) return the sum of all the distance to each centroid, and b) it doesn't have any sort of iteration limit or cut off which ensures the quality of the clustering. python-clustering and the clustering algorithm on daniweb doesn't really work for me. Can someone find me a good lib? Google hasn't been my friend

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  • Is MacBook powerful enough to do Ipad development? or do I need a MacBook Pro?

    - by ronaldwidha
    The title probably says it all. Considering an ipad's processor is nothing compared to a macbook, I would think a Macbook should be more than capable to run the simulator. However, not knowing much about iphone/ipad development, I'd like to get some opinions on this. for e.g. how many apps are typically need to be run for ipad dev (editor, debugger, perf monitor, trace log, etc). are these apps resource (memory, cpu) intensive? please do not take into consideration the actual image, 3d, video, sound development. I understand one would need quite a beefy machine to produce these type of creative assets. What I'm looking at is a machine to do code development, physics, putting together the produced assets (images, vector graphics, 3d video, sound, etc).

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  • How to convert an existing callback interface to use boost signals & slots

    - by the_mandrill
    I've currently got a class that can notify a number of other objects via callbacks: class Callback { virtual NodulesChanged() =0; virtual TurkiesTwisted() =0; }; class Notifier { std::vector<Callback*> m_Callbacks; void AddCallback(Callback* cb) {m_Callbacks.push(cb); } ... void ChangeNodules() { for (iterator it=m_Callbacks.begin(); it!=m_Callbacks.end(); it++) { (*it)->NodulesChanged(); } } }; I'm considering changing this to use boost's signals and slots as it would be beneficial to reduce the likelihood of dangling pointers when the callee gets deleted, among other things. However, as it stands boost's signals seems more oriented towards dealing with function objects. What would be the best way of adapting my code to still use the callback interface but use signals and slots to deal with the connection and notification aspects?

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  • Why does gcc think that I am trying to make a function call in my template function signature?

    - by nieldw
    GCC seem to think that I am trying to make a function call in my template function signature. Can anyone please tell me what is wrong with the following? 227 template<class edgeDecor, class vertexDecor, bool dir> 228 vector<Vertex<edgeDecor,vertexDecor,dir>> Graph<edgeDecor,vertexDecor,dir>::vertices() 229 { 230 return V; 231 }; GCC is giving the following: graph.h:228: error: a function call cannot appear in a constant-expression graph.h:228: error: template argument 3 is invalid graph.h:228: error: template argument 1 is invalid graph.h:228: error: template argument 2 is invalid graph.h:229: error: expected unqualified-id before ‘{’ token Thanks a lot.

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  • R - Specifying colClasses in the read.csv

    - by Derek
    Hi, I am trying to specify the colClasses options in the read.csv function in R. In my data, the first column "time" is basically a character vector while the rest of the columns are numeric. data<-read.csv("test.csv" , comment.char="" , colClasses=c(time="character","numeric") , strip.white=FALSE) In the above command, I would want R to read in the "time" column as "character" and the as numeric. Although, the "data" variable did have the correct result after the command completed, R returned the following warnings. I am wondering how I could fix these warnings? Warning messages: 1: In read.table(file = file, header = header, sep = sep, quote = quote, : not all columns named in 'colClasses' exist 2: In tmp[i[i > 0L]] <- colClasses : number of items to replace is not a multiple of replacement length Thank in advance Derek

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  • In using Samsung acclerometer

    - by cheesebunz
    Hi everyone , i have this sample code i want to use. I'm not sure where to place it. I'm using Visual studio 2008 , windows mobile 6 sdk. I wish to test the accelerometer but i'm not sure where i should code it. The start is e.g. form1. Do i create new existing item new program.cs a new C# file and do this(as of below)? #include "smiAccelerometer.h" SmiAccelerometerVector accel; // get the acceleration vector containing X, Y, Z components if (SmiAccelerometerGetVector(&accel) == SMI_SUCCESS) { // Successfully got acceleration. // Use accel.x, accel.y and accel.z in your application } else { // failed to get the acceleration }

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  • Projection matrix + world plane ~> Homography from image plane to world plane

    - by B3ret
    I think I have my wires crossed on this, it should be quite easy. I have a projection matrix from world coordinates to image coordinates (4D homogeneous to 3D homgeneous), and therefore I also have the inverse projection matrix from image coordinates to world "rays". I want to project points of the image back onto a plane within the world (which is given of course as 4D homogeneous vector). The needed homography should be uniquely identified, yet I can not figure out how to compute it. Of course I could also intersect the back-projected rays with the world plane, but this seems not a good way, knowing that there MUST be a homography doing this for me. Thanks in advance, Ben

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