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  • How to center an R plot after removing axis labels

    - by ConnorG
    I'm working on visualizing a matrix in R (almost exactly like http://reference.wolfram.com/mathematica/ref/MatrixPlot.html), and I've been using image(<matrix>,axes=FALSE) to draw the picture. However, I noticed that with the y-axis turned off, the plot isn't centered--the space is still there for the axis ticks + label. I can finagle some centering with par(oma=c(0,0,0,2.5)) but this seems inefficient and error-prone (if my matrix were to change dimensions/become non-square). Is there a better way to force the graphic to center? The right hand margin is significantly smaller than the left.

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  • Scaling larger Image problem.

    - by krishna
    Hi, I m developing flex application, in which I want to Draw Image from User local hard-drive to the canvas of size 640x360. User can choose Image of bigger resolution & is scaled to Canvas size. But if user selected images of larger resolution like 3000x2000, the scaling take lot time & freezes the application until scale done. Is there any method to scale image faster or kind of threading can be done? I am using matrix to scale Image as below: var mat:Matrix = new Matrix(); var scalex:Number = canvasScreen.width/content.width; var scaley:Number = canvasScreen.height/content.height; mat.scale(scalex,scaley); canvasScreen.graphics.clear(); canvasScreen.graphics.beginBitmapFill(content.bitmapData,mat);

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  • WPF Animate a Maxtrix using interpolation

    - by Mark
    Im having a issue with my application that is using touch gestures to scale, translate and rotate my scene. I was using a TransformGroup which contained TranslateTransform, ScaleTransform and a RotateTransform but I could not get the movement correct, it always jumps and skips, so I moved to a MaxtrixTransform which I was able to use much easier to get my scene to be zoomable, rotatable and panable nicely. However, what I later found out was that you cannot animate smoothly (using interpolation) the values of a Matrix, for what reason I have no idea, but its part of the MSDN doco and the properties of the Matrix are not dependency properties anyways... Has anyone had any luck animating a maxtrix to make it smooth? The only idea(s) I have had is to animate a few different, custom DP which all have callbacks that I update the Matrix from OR To convert the Maxtix to a set of Transform object that I then animate and then afterwords convert back. Is there a smarter way to do this?

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  • Avoid the use of loops (for) with R

    - by albergali
    Hi, I'm working with R and I have a code like this: i<-1 j<-1 for (i in 1:10) for (j in 1:100) if (data[i] == paths[j,1]) cluster[i,4] <- paths[j,2] where : data is a vector with 100 rows and 1 column paths is a matrix with 100 rows and 5 columns cluster is a matrix with 100 rows and 5 columns My question is: how could I avoid the use of "for" loops to iterate through the matrix? I don't know whether apply functions (lapply, tapply...) are useful in this case. This is a problem when j=10000 for example, because execution time is very long. Thank you

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  • Divide numpy array

    - by BandGap
    Hi all I have some data represented in a 1300x1341 matrix. I would like to split this matrix in several pieces (e.g. 9) so that I can loop over and process them. The data needs to stay ordered in the sense that x[0,1] stays below (or above if you like) x[0,0] and besides x[1,1]. Just like if you had imaged the data, you could draw 2 vertical and 2 horizontal lines over the image to illustrate the 9 parts. If I use numpys reshape (eg. matrix.reshape(9,260,745) or any other combination of 9,260,745) it doesn't yield the required structure since the above mentioned ordering is lost... Did I misunderstand the reshape method or can it be done this way? What other pythonic/numpy way is there to do this?

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  • Matlab Question - Principal Component Analysis

    - by Jack
    I have a set of 100 observations where each observation has 45 characteristics. And each one of those observations have a label attached which I want to predict based on those 45 characteristics. So it's an input matrix with the dimension 45 x 100 and a target matrix with the dimension 1 x 100. The thing is that I want to know how many of those 45 characteristics are relevant in my set of data, basically the principal component analysis, and I understand that I can do this with Matlab function processpca. Could you please tell me how can I do this? Suppose that the input matrix is x with 45 rows and 100 columns and y is a vector with 100 elements.

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  • C++ operator overloading doubt

    - by avd
    I have a code base, in which for Matrix class, these two definitions are there for () operator: template <class T> T& Matrix<T>::operator() (unsigned row, unsigned col) { ...... } template <class T> T Matrix<T>::operator() (unsigned row, unsigned col) const { ...... } One thing I understand is that the second one does not return the reference but what does const mean in the second declaration. Also which function is called when I do say mat(i,j)

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  • troubles with integration on matlab

    - by user648666
    I'd like some help please I really need to solve this problem. Well before anything thank you for your time... My problem: I have a matrix (826x826 double) and I want to integrate this matrix with respect to a vector of (826x1 double) I don't have the functions of any of this. Is there a command or an algorithm to take the integral of a matrix with respect to a vector? Please I really need help, I'm such a newbie at matlab. Sincerely. George

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  • Creating triangles using borders

    - by Interstellar_Coder
    I recently needed to create speech bubbles. To create the little tip at the end of the speech bubble, i used a css technique where the element is given a 0 width and 0 height and given borders. Making certain borders transparent would create diagonals. This works great, and i am able to manipulate different borders to create triangles/shapes to my liking. The problem is, i don't fully understand why this works. I understand that it all starts out with a rectangle and as you set one or more of the borders to transparent it creates a diagonal. My question is how does this work ? And why does it create a diagonal in the first place ? EDIT: To clarify, i would like to know the theory behind why this technique works.

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  • "Othello" game needs some clarification

    - by pappu
    I am trying to see if my understanding of "othello" fame is correct or not. According to the rules, we flip the dark/light sides if we get some sequence like X000X = XXXXX. The question I have is if in the process of flipping 0-X or X- 0, do we also need to consider the rows/columns/diagonals of newly flipped elements? e.g. consider board state as shown in above image(New element X is placed @ 2,3) When we update board, we mark elements from 2,3 to 6,3 as Xs but in this process elements like horizontal 4,3 to 4,5 and diagonal 2,3 to 4,5 are also eligible for update? so do we update those elements as well? or just the elements which have starting as 2,3 (i.e update rows/column/diagonal whose starting point is the element we are dealing with, in our case 2,3?) Please help me understand it

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  • if non zero elements in same column count only once

    - by George
    I want to check the elements above the main diagonal and if I found non zero values , count one. If the non zero values are found in the same column ,then count just one ,not the number of the non zero values. For example , it should be count = 2 and not 3 in this example because 12 and 6 are in the same column. A= 1 11 12 4 5 6 0 7 0 #include <stdio.h> #include <stdlib.h> #include <math.h> int main( int argc, const char* argv[] ){ int Rows = 3 , Cols = 3; float *A = (float *) malloc ( Rows * Cols * sizeof (float) ); A[0] = 1.0; A[1] = 11.0; A[2] = 12.0; A[3] = 4.0; A[4] = 5.0; A[5] = 6.0; A[6] = 0.0; A[7] = 7.0; A[8] = 0.0; // print input matrix printf("\n Input matrix \n\n"); for ( int i = 0; i < Rows; i++ ) for ( int j = 0; j < Cols; j++ ) { printf("%f\t",A[ i * Cols + j ]); if( j == Cols-1 ) printf("\n"); } printf("\n"); int count = 0; for ( int j = 0 ; j < Cols; j++ ) { for ( int i = ( Rows - 1 ); i >= 0; i-- ) { // check the diagonal elements above the main diagonal if ( j > i ) { if ( ( A[ i * Cols + j ] != 0 ) ) { printf("\n Above nonzero Elmts = %f\n",( A[i * Cols + j] ) ); count++; } } } } printf("\ncount = %d\n",count ); return 0; }

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  • Doesn't Matlab optimize the following?

    - by kloop
    I have a very long vector 1xr v, and a very long vector w 1xs, and a matrix A rxs, which is sparse (but very big in dimensions). I was expecting the following to be optimized by Matlab so I won't run into trouble with memory: A./(v'*w) but it seems like Matlab is actually trying to generate the full v'*w matrix, because I am running into Out of memory issue. Is there a way to overcome this? Note that there is no need to calculate all v'*w because many values of A are 0. EDIT: If that were possible, one way to do it would be to do A(find(A)) ./ (v'*w)(find(A)); but you can't select a subset of a matrix (v'*w in this case) without first calculating it and putting it in a variable.

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  • Multi-threading does not work correctly using std::thread (C++ 11)

    - by user1364743
    I coded a small c++ program to try to understand how multi-threading works using std::thread. Here's the step of my program execution : Initialization of a 5x5 matrix of integers with a unique value '42' contained in the class 'Toto' (initialized in the main). I print the initialized 5x5 matrix. Declaration of std::vector of 5 threads. I attach all threads respectively with their task (threadTask method). Each thread will manipulate a std::vector<int> instance. I join all threads. I print the new state of my 5x5 matrix. Here's the output : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 It should be : 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 0 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 Here's the code sample : #include <iostream> #include <vector> #include <thread> class Toto { public: /* ** Initialize a 5x5 matrix with the 42 value. */ void initData(void) { for (int y = 0; y < 5; y++) { std::vector<int> vec; for (int x = 0; x < 5; x++) { vec.push_back(42); } this->m_data.push_back(vec); } } /* ** Display the whole matrix. */ void printData(void) const { for (int y = 0; y < 5; y++) { for (int x = 0; x < 5; x++) { printf("%d ", this->m_data[y][x]); } printf("\n"); } printf("\n"); } /* ** Function attached to the thread (thread task). ** Replace the original '42' value by another one. */ void threadTask(std::vector<int> &list, int value) { for (int x = 0; x < 5; x++) { list[x] = value; } } /* ** Return the m_data instance propertie. */ std::vector<std::vector<int> > &getData(void) { return (this->m_data); } private: std::vector<std::vector<int> > m_data; }; int main(void) { Toto toto; toto.initData(); toto.printData(); //Display the original 5x5 matrix (first display). std::vector<std::thread> threadList(5); //Initialization of vector of 5 threads. for (int i = 0; i < 5; i++) { //Threads initializationss std::vector<int> vec = toto.getData()[i]; //Get each sub-vectors. threadList.at(i) = std::thread(&Toto::threadTask, toto, vec, i); //Each thread will be attached to a specific vector. } for (int j = 0; j < 5; j++) { threadList.at(j).join(); } toto.printData(); //Second display. getchar(); return (0); } However, in the method threadTask, if I print the variable list[x], the output is correct. I think I can't print the correct data in the main because the printData() call is in the main thread and the display in the threadTask function is correct because the method is executed in its own thread (not the main one). It's strange, it means that all threads created in a parent processes can't modified the data in this parent processes ? I think I forget something in my code. I'm really lost. Does anyone can help me, please ? Thank a lot in advance for your help.

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  • Restrict sprite movement to vertical and horizontal

    - by Daniel Granger
    I have been battling with this for some time and my noob brain can't quite work it out. I have a standard tile map and currently use the following code to move my enemy sprite around the map -(void) movePlayer:(ccTime)deltaTime { if (CGPointEqualToPoint(self.position, requestedPosition)) return; float step = kPlayerSpeed * deltaTime; float dist = ccpDistance(self.position, requestedPosition); CGPoint vectorBetweenAB = ccpSub(self.position, requestedPosition); if (dist <= step) { self.position = requestedPosition; [self popPosition]; } else { CGPoint normVectorBetweenAB = ccpNormalize(vectorBetweenAB); CGPoint movementVectorForThisFrame = ccpMult(normVectorBetweenAB, step); if (abs(vectorBetweenAB.x) > abs(vectorBetweenAB.y)) { if (vectorBetweenAB.x > 0) { [self runAnimation:walkLeft]; } else { [self runAnimation:walkRight]; } } else { if (vectorBetweenAB.y > 0) { [self runAnimation:walkDown]; } else { [self runAnimation:walkUp]; } } if (self.position.x > movementVectorForThisFrame.x) { movementVectorForThisFrame.x = -movementVectorForThisFrame.x; } if (self.position.y > movementVectorForThisFrame.y) { movementVectorForThisFrame.y = -movementVectorForThisFrame.y; } self.position = ccpAdd(self.position, movementVectorForThisFrame); } } movePlayer: is called by the classes updateWithDeltaTime: method. the ivar requestedPosition is set in the updateWithDeltaTime method as well, it basically gets the next point out of a queue to move to. These points can be anywhere on the map, so if they are in a diagonal direction from the enemy the enemy sprite will move directly to that point. But how do I change the above code to restrict the movement to vertical and horizontal movement only so that the enemies movement 'staircases' its way along a diagonal path, taking the manhattan distance (I think its called). As shown by my crude drawing below... S being the start point F being the finish and the numbers being each intermediate point along its path to create a staircase type diagonal movement. Finally I intend to be able to toggle this behaviour on and off, so that I can choose whether or not I want the enemy to move free around the map or be restricted to this horizontal / vertical movement only. | | | | | | | | | | | | | | | | | | | | | |F| | | | | | | | | |5|4| | | | | | | | | |3|2| | | | | | | | | |1|S| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

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  • Cannot create an array of LinkedLists in Java...?

    - by kchau
    I'm working on a sparse matrix class that needs to use an array of LinkedLists to store the values of a matrix. Each element of the array (i.e. each LinkedList) represents a row of the matrix. And, each element in the LinkedLists represents a column and the stored value. In my class, I have a declaration of the array as: private LinkedList<IntegerNode>[] myMatrix; And, in my constructor for the SparseMatrix, I try to define: myMatrix = new LinkedList<IntegerNode>[numRows]; The error I end up getting is "Cannot create a generic array of LinkedList<IntegerNode>." So, I have two issues with this, 1) What am I doing wrong, and 2) Why is the type acceptable in the declaration for the array if it can't be created? Edit: IntegerNode is a class that I have created. And, all of my class files are packaged together.

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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  • Improving first person camera and implementing third person camera

    - by brainydexter
    I want to improve upon my first person camera implementation and extend it to, so the user can toggle between third person/first person view. My current setup: draw():: glPushMatrix(); m_pCamera->ApplyCameraTransform(); // Render gameObjects glPopMatrix(); Camera is strongly coupled to the player, so much so, that it is a friend of player. This is what the Camera::ApplyCameraTransform looks like: glm::mat4 l_TransformationMatrix; m_pPlayer->m_pTransformation->GetTransformation(l_TransformationMatrix, false); l_TransformationMatrix = glm::core::function::matrix::inverse(l_TransformationMatrix); glMultMatrixf(glm::value_ptr(l_TransformationMatrix)); So, I take the player's transformation matrix and invert it to yield First person camera view. Since, Third person camera view is just a 'translated' first person view behind the player; what would be a good way to improve upon this (keeping in mind that I will be extending it to Third person camera as well. Thanks

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  • BoundingBox created from mesh to origin, making it bigger

    - by Gunnar Södergren
    I'm working on a level-based survival game and I want to design my scenes in Maya and export them as a single model (with multiple meshes) into XNA. My problem is that when I try to create Bounding Boxes(for Collision purposes) for each of the meshes, the are calculated from origin to the far-end of the current mesh, so to speak. I'm thinking that it might have something to do with the position each mesh brings from Maya and that it's interpreted wrongly... or something. Here's the code for when I create the boxes: private static BoundingBox CreateBoundingBox(Model model, ModelMesh mesh) { Matrix[] boneTransforms = new Matrix[model.Bones.Count]; model.CopyAbsoluteBoneTransformsTo(boneTransforms); BoundingBox result = new BoundingBox(); foreach (ModelMeshPart meshPart in mesh.MeshParts) { BoundingBox? meshPartBoundingBox = GetBoundingBox(meshPart, boneTransforms[mesh.ParentBone.Index]); if (meshPartBoundingBox != null) result = BoundingBox.CreateMerged(result, meshPartBoundingBox.Value); } result = new BoundingBox(result.Min, result.Max); return result; } private static BoundingBox? GetBoundingBox(ModelMeshPart meshPart, Matrix transform) { if (meshPart.VertexBuffer == null) return null; Vector3[] positions = VertexElementExtractor.GetVertexElement(meshPart, VertexElementUsage.Position); if (positions == null) return null; Vector3[] transformedPositions = new Vector3[positions.Length]; Vector3.Transform(positions, ref transform, transformedPositions); for (int i = 0; i < transformedPositions.Length; i++) { Console.WriteLine(" " + transformedPositions[i]); } return BoundingBox.CreateFromPoints(transformedPositions); } public static class VertexElementExtractor { public static Vector3[] GetVertexElement(ModelMeshPart meshPart, VertexElementUsage usage) { VertexDeclaration vd = meshPart.VertexBuffer.VertexDeclaration; VertexElement[] elements = vd.GetVertexElements(); Func<VertexElement, bool> elementPredicate = ve => ve.VertexElementUsage == usage && ve.VertexElementFormat == VertexElementFormat.Vector3; if (!elements.Any(elementPredicate)) return null; VertexElement element = elements.First(elementPredicate); Vector3[] vertexData = new Vector3[meshPart.NumVertices]; meshPart.VertexBuffer.GetData((meshPart.VertexOffset * vd.VertexStride) + element.Offset, vertexData, 0, vertexData.Length, vd.VertexStride); return vertexData; } } Here's a link to the picture of the mesh(The model holds six meshes, but I'm only rendering one and it's bounding box to make it clearer: http://www.gsodergren.se/portfolio/wp-content/uploads/2011/10/Screen-shot-2011-10-24-at-1.16.37-AM.png The mesh that I'm refering to is the Cubelike one. The cylinder is a completely different model and not part of any bounding box calculation. I've double- (and tripple-)-checked that this mesh corresponds to this bounding box. Any thoughts on what I'm doing wrong?

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  • 2D OBB collision detection, resolving collisions?

    - by Milo
    I currently use OBBs and I have a vehicle that is a rigid body and some buildings. Here is my update() private void update() { camera.setPosition((vehicle.getPosition().x * camera.getScale()) - ((getWidth() ) / 2.0f), (vehicle.getPosition().y * camera.getScale()) - ((getHeight() ) / 2.0f)); //camera.move(input.getAnalogStick().getStickValueX() * 15.0f, input.getAnalogStick().getStickValueY() * 15.0f); if(input.isPressed(ControlButton.BUTTON_GAS)) { vehicle.setThrottle(1.0f, false); } if(input.isPressed(ControlButton.BUTTON_BRAKE)) { vehicle.setBrakes(1.0f); } vehicle.setSteering(input.getAnalogStick().getStickValueX()); vehicle.update(16.6666f / 1000.0f); ArrayList<Building> buildings = city.getBuildings(); for(Building b : buildings) { if(vehicle.getRect().overlaps(b.getRect())) { vehicle.update(-17.0f / 1000.0f); break; } } } The collision detection works well. What doesn't is how they are dealt with. My goal is simple. If the vehicle hits a building, it should stop, and never go into the building. When I apply negative torque to reverse the car should not feel buggy and move away from the building. I don't want this to look buggy. This is my rigid body class: class RigidBody extends Entity { //linear private Vector2D velocity = new Vector2D(); private Vector2D forces = new Vector2D(); private float mass; //angular private float angularVelocity; private float torque; private float inertia; //graphical private Vector2D halfSize = new Vector2D(); private Bitmap image; public RigidBody() { //set these defaults so we don't get divide by zeros mass = 1.0f; inertia = 1.0f; } //intialize out parameters public void initialize(Vector2D halfSize, float mass, Bitmap bitmap) { //store physical parameters this.halfSize = halfSize; this.mass = mass; image = bitmap; inertia = (1.0f / 20.0f) * (halfSize.x * halfSize.x) * (halfSize.y * halfSize.y) * mass; RectF rect = new RectF(); float scalar = 10.0f; rect.left = (int)-halfSize.x * scalar; rect.top = (int)-halfSize.y * scalar; rect.right = rect.left + (int)(halfSize.x * 2.0f * scalar); rect.bottom = rect.top + (int)(halfSize.y * 2.0f * scalar); setRect(rect); } public void setLocation(Vector2D position, float angle) { getRect().set(position, getWidth(), getHeight(), angle); } public Vector2D getPosition() { return getRect().getCenter(); } @Override public void update(float timeStep) { //integrate physics //linear Vector2D acceleration = Vector2D.scalarDivide(forces, mass); velocity = Vector2D.add(velocity, Vector2D.scalarMultiply(acceleration, timeStep)); Vector2D c = getRect().getCenter(); c = Vector2D.add(getRect().getCenter(), Vector2D.scalarMultiply(velocity , timeStep)); setCenter(c.x, c.y); forces = new Vector2D(0,0); //clear forces //angular float angAcc = torque / inertia; angularVelocity += angAcc * timeStep; setAngle(getAngle() + angularVelocity * timeStep); torque = 0; //clear torque } //take a relative Vector2D and make it a world Vector2D public Vector2D relativeToWorld(Vector2D relative) { Matrix mat = new Matrix(); float[] Vector2Ds = new float[2]; Vector2Ds[0] = relative.x; Vector2Ds[1] = relative.y; mat.postRotate(JMath.radToDeg(getAngle())); mat.mapVectors(Vector2Ds); return new Vector2D(Vector2Ds[0], Vector2Ds[1]); } //take a world Vector2D and make it a relative Vector2D public Vector2D worldToRelative(Vector2D world) { Matrix mat = new Matrix(); float[] Vectors = new float[2]; Vectors[0] = world.x; Vectors[1] = world.y; mat.postRotate(JMath.radToDeg(-getAngle())); mat.mapVectors(Vectors); return new Vector2D(Vectors[0], Vectors[1]); } //velocity of a point on body public Vector2D pointVelocity(Vector2D worldOffset) { Vector2D tangent = new Vector2D(-worldOffset.y, worldOffset.x); return Vector2D.add( Vector2D.scalarMultiply(tangent, angularVelocity) , velocity); } public void applyForce(Vector2D worldForce, Vector2D worldOffset) { //add linear force forces = Vector2D.add(forces ,worldForce); //add associated torque torque += Vector2D.cross(worldOffset, worldForce); } @Override public void draw( GraphicsContext c) { c.drawRotatedScaledBitmap(image, getPosition().x, getPosition().y, getWidth(), getHeight(), getAngle()); } } Essentially, when any rigid body hits a building it should exhibit the same behavior. How is collision solving usually done? Thanks

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  • How to label a cuboid?

    - by usha
    Hi this is how my 3dcuboid looks, I have attached the complete code. I want to label this cuboid using different names across sides, how is this possible using opengl on android? public class MyGLRenderer implements Renderer { Context context; Cuboid rect; private float mCubeRotation; // private static float angleCube = 0; // Rotational angle in degree for cube (NEW) // private static float speedCube = -1.5f; // Rotational speed for cube (NEW) public MyGLRenderer(Context context) { rect = new Cuboid(); this.context = context; } public void onDrawFrame(GL10 gl) { // TODO Auto-generated method stub gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glLoadIdentity(); // Reset the model-view matrix gl.glTranslatef(0.2f, 0.0f, -8.0f); // Translate right and into the screen gl.glScalef(0.8f, 0.8f, 0.8f); // Scale down (NEW) gl.glRotatef(mCubeRotation, 1.0f, 1.0f, 1.0f); // gl.glRotatef(angleCube, 1.0f, 1.0f, 1.0f); // rotate about the axis (1,1,1) (NEW) rect.draw(gl); mCubeRotation -= 0.15f; //angleCube += speedCube; } public void onSurfaceChanged(GL10 gl, int width, int height) { // TODO Auto-generated method stub if (height == 0) height = 1; // To prevent divide by zero float aspect = (float)width / height; // Set the viewport (display area) to cover the entire window gl.glViewport(0, 0, width, height); // Setup perspective projection, with aspect ratio matches viewport gl.glMatrixMode(GL10.GL_PROJECTION); // Select projection matrix gl.glLoadIdentity(); // Reset projection matrix // Use perspective projection GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.f); gl.glMatrixMode(GL10.GL_MODELVIEW); // Select model-view matrix gl.glLoadIdentity(); // Reset } public void onSurfaceCreated(GL10 gl, EGLConfig config) { // TODO Auto-generated method stub gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set color's clear-value to black gl.glClearDepthf(1.0f); // Set depth's clear-value to farthest gl.glEnable(GL10.GL_DEPTH_TEST); // Enables depth-buffer for hidden surface removal gl.glDepthFunc(GL10.GL_LEQUAL); // The type of depth testing to do gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); // nice perspective view gl.glShadeModel(GL10.GL_SMOOTH); // Enable smooth shading of color gl.glDisable(GL10.GL_DITHER); // Disable dithering for better performance }} public class Cuboid{ private FloatBuffer mVertexBuffer; private FloatBuffer mColorBuffer; private ByteBuffer mIndexBuffer; private float vertices[] = { //width,height,depth -2.5f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -2.5f, 1.0f, -1.0f, -2.5f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -2.5f, 1.0f, 1.0f }; private float colors[] = { // R,G,B,A COLOR 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f }; private byte indices[] = { // VERTEX 0,1,2,3,4,5,6,7 REPRESENTATION FOR FACES 0, 4, 5, 0, 5, 1, 1, 5, 6, 1, 6, 2, 2, 6, 7, 2, 7, 3, 3, 7, 4, 3, 4, 0, 4, 7, 6, 4, 6, 5, 3, 0, 1, 3, 1, 2 }; public Cuboid() { ByteBuffer byteBuf = ByteBuffer.allocateDirect(vertices.length * 4); byteBuf.order(ByteOrder.nativeOrder()); mVertexBuffer = byteBuf.asFloatBuffer(); mVertexBuffer.put(vertices); mVertexBuffer.position(0); byteBuf = ByteBuffer.allocateDirect(colors.length * 4); byteBuf.order(ByteOrder.nativeOrder()); mColorBuffer = byteBuf.asFloatBuffer(); mColorBuffer.put(colors); mColorBuffer.position(0); mIndexBuffer = ByteBuffer.allocateDirect(indices.length); mIndexBuffer.put(indices); mIndexBuffer.position(0); } public void draw(GL10 gl) { gl.glFrontFace(GL10.GL_CW); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVertexBuffer); gl.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_COLOR_ARRAY); gl.glDrawElements(GL10.GL_TRIANGLES, 36, GL10.GL_UNSIGNED_BYTE, mIndexBuffer); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_COLOR_ARRAY); } } public class Draw3drect extends Activity { private GLSurfaceView glView; // Use GLSurfaceView // Call back when the activity is started, to initialize the view @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); glView = new GLSurfaceView(this); // Allocate a GLSurfaceView glView.setRenderer(new MyGLRenderer(this)); // Use a custom renderer this.setContentView(glView); // This activity sets to GLSurfaceView } // Call back when the activity is going into the background @Override protected void onPause() { super.onPause(); glView.onPause(); } // Call back after onPause() @Override protected void onResume() { super.onResume(); glView.onResume(); } }

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  • extrapolating object state based on updates

    - by user494461
    I have a networked multi-user collaborative application. To maintain a consistent virtual world, I send updates for objects from a master peer to a guest peer. The update state contains x,y,z coordinates of object center and his rotation matrix(CHAI3d api used a 3x3 matrix) with 30Hz frequency. I want to reduce this update rate and want to send with a reduced update rate. I want a predictor on both peers. When the predicted value is outside, say a error value of 10% in comparison to master peers objects original state the master peer triggers a state update. Now for position I used velocity,position updates so that the guest peer can extrapolate position. Like velocity for position what parameter should I use for rotation extrapolition?

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  • How to get quality sprite sheet generation with rotations

    - by BenMaddox
    I'm working on a game that uses sprite sheets with rotation for animations. While the effect is pretty good, the quality of the rotations is somewhat lacking. I exported a flash animation to png sequence and then used a C# app to do matrix based rotations (System.Drawing.Drawing2D.Matrix). Unfortunately, there are several places where the image gets clipped. What would you suggest for a way to get high quality rotations from either flash or the exported PNGs? A circle should fit within the same image boundaries. I don't mind a new program that I must write or an existing program I must download/buy.

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  • Camera not staying behind model while moving in circle

    - by ChocoMan
    I have a camera behind a model (3rd Person) and I'm having problems KEEPING it behind the model. When I first start my game, you see the back of the model. If the model moves forward, backward or strafe left or right, the camera moves along accordingly. When the model rotates (stationary), the camera rotates accordingly with the model still pointing at the model's back. So far, so good. The problem comes when the player is BOTH moving and rotating at the same time. Take for example a model moving in a circular pattern like running around a track. As the model moves in this motion, the model rotates slightly more with each complete rotation. Eventually, instead of looking at the model's back, eventually you will see the model in a profile view and before you know it, the model's front is facing the camera. And when you stop moving the model, the model stays in that position. So, as long as my model is stationary and rotating in one place, the camera rotates correctly. But as soon as there is any sort movement while rotating, the model is offset by a mysterious increasing amount. How can I keep the camera maintaining the same view no matter how I move AND rotate at the same time? // Rotates model and pitches camera on its own axis public void modelRotMovement(GamePadState pController) { /* For rotating the model left or right. * Camera maintains distance from model * throughout rotation and if model moves * to a new position. */ Yaw = pController.ThumbSticks.Right.X * MathHelper.ToRadians(speedAngleMAX); AddRotation = Quaternion.CreateFromAxisAngle(Vector3.Up, yaw); //AddRotation = Quaternion.CreateFromYawPitchRoll(Yaw, 0, 0); ModelLoad.MRotation *= AddRotation; MOrientation = Matrix.CreateFromQuaternion(ModelLoad.MRotation); Pitch = pController.ThumbSticks.Right.Y * MathHelper.ToRadians(speedAngleMAX); AddPitch = Quaternion.CreateFromAxisAngle(Vector3.Up, pitch); ModelLoad.CRotation *= AddPitch; COrientation = Matrix.CreateFromQuaternion(ModelLoad.CRotation); } // Orbit (yaw) Camera around model public void cameraYaw(float yaw) { Vector3 yawAngle = ModelLoad.CameraPos - ModelLoad.camTarget; Vector3 axisYaw = Vector3.Up; ModelLoad.CameraPos = Vector3.Transform(yawAngle, Matrix.CreateFromAxisAngle(axisYaw, yaw)) + ModelLoad.camTarget; }

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  • Smooth Camera Rotation around 90 degrees

    - by Nicholas
    I'm developing a third person 3D platformer in XNA. My problem is when I try to rotate the camera around the player. I would like to rotate (and animate) the camera 90 degrees around the player. So the camera should rotate until it has reached 90 degrees from the starting position. I cannot figure out how to keep track of the rotation, and when the rotation has made the full 90 degrees. Currently my cameras update: public void Update(Vector3 playerPosition) { if (rotateCamera) { position = Vector3.Transform(position - playerPosition, Matrix.CreateRotationY(0.1f)) + playerPosition; } this.viewMatrix = Matrix.CreateLookAt(position, playerPosition, Vector3.Up); } The initial position of the camera is set in the constructor. The "rotateCamera" bool is set on keypress. Thanks for the help in advance. Cheers.

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