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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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• Moving characters on a grid [on hold]

  - by madmax1

  i am developing my first game with C++. My game uses a grid of rectangles. I have a class Board which manages the grid as a whole, initializes the terrain, places/removes characters, etc. It has a 2D vector of a class Field, which handles the Structure of the field, contained Objects, Characters, etc. Field again contains a vector of class Character, which are positioned on the field. Now i want to implement the functionality to move a character on the board, however dont know which is best practice to do so. Should i implement a moveCharacter(character, offset) function in Board, make it search for the character and move it? Or should i implement a function move(offset) in Character? This sure would be nicest, however makes characters necessary to know the board they are on, or the field which in turn knows the board. On the one hand i feel like i should avoid inclusion between classes as much as possible e.g. to increase portability of classes for different projects, on the other hand i think the character.move() functionality is most comfortable for further development. Im pretty new to "bigger" C++ projects and these kind of design questions pop up more and more often lately and i have troubles deciding. Thanks a lot for any advice!

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• Calculating the correct particle angle in an outwards explosion

  - by Sun

  I'm creating a simple particle explosion but am stuck in finding the correct angle to rotate my particle. The effect I'm going for is similar to this: Where each particle is going outwards from the point of origin and at the correct angle. This is what I currently have: As you can see, each particle is facing the same angle, but I'm having a little difficulty figuring out the correct angle. I have the vector for the point of emission and the new vector for each particle, how can I use this to calculate the angle? Some code for reference: private Particle CreateParticle() { ... Vector2 velocity = new Vector2(2.0f * (float)(random.NextDouble() * 2 - 1), 2.0f * (float)(random.NextDouble() * 2 - 1)); direction = velocity - ParticleLocation; float angle = (float)Math.Atan2(direction.Y, direction.X); ... return new Particle(texture, position, velocity, angle, angularVelocity, color, size, ttl, EmitterLocation); } I am then using the angle created as so in my particles Draw method: spriteBatch.Draw(Texture, Position, null, Color, Angle, origin, Size, SpriteEffects.None, 0f);

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• Rotating wheel with touch (adding momentum and slowing down the initial rate it can be moved

  - by Lewis

  I have a wheel control in a game which is setup like so: - (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint location = [touch locationInView:[touch view]]; location = [[CCDirector sharedDirector] convertToGL:location]; if (CGRectContainsPoint(wheel.boundingBox, location)) { CGPoint firstLocation = [touch previousLocationInView:[touch view]]; CGPoint location = [touch locationInView:[touch view]]; CGPoint touchingPoint = [[CCDirector sharedDirector] convertToGL:location]; CGPoint firstTouchingPoint = [[CCDirector sharedDirector] convertToGL:firstLocation]; CGPoint firstVector = ccpSub(firstTouchingPoint, wheel.position); CGFloat firstRotateAngle = -ccpToAngle(firstVector); CGFloat previousTouch = CC_RADIANS_TO_DEGREES(firstRotateAngle); CGPoint vector = ccpSub(touchingPoint, wheel.position); CGFloat rotateAngle = -ccpToAngle(vector); CGFloat currentTouch = CC_RADIANS_TO_DEGREES(rotateAngle); wheelRotation += (currentTouch - previousTouch) * 0.6; //limit speed 0.6 } } Now once the user lets go of the wheel I want it to rotate back to where it was before but not without taking into account the momentum of the swipe the user has done. This is the bit I really can't get my head around. So if the swipe generates a lot of momentum then the wheel will carry on moving slightly in that direction until the overall force which pulls the wheel back to the starting position kicks in. Any ideas/code snippets?

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• Can someone explain the (reasons for the) implications of colum vs row major in multiplication/concatenation?

  - by sebf

  I am trying to learn how to construct view and projection matrices, and keep reaching difficulties in my implementation owing to my confusion about the two standards for matrices. I know how to multiply a matrix, and I can see that transposing before multiplication would completely change the result, hence the need to multiply in a different order. What I don't understand though is whats meant by only 'notational convention' - from the articles here and here the authors appear to assert that it makes no difference to how the matrix is stored, or transferred to the GPU, but on the second page that matrix is clearly not equivalent to how it would be laid out in memory for row-major; and if I look at a populated matrix in my program I see the translation components occupying the 4th, 8th and 12th elements. Given that: "post-multiplying with column-major matrices produces the same result as pre-multiplying with row-major matrices. " Why in the following snippet of code: Matrix4 r = t3 * t2 * t1; Matrix4 r2 = t1.Transpose() * t2.Transpose() * t3.Transpose(); Does r != r2 and why does pos3 != pos for: Vector4 pos = wvpM * new Vector4(0f, 15f, 15f, 1); Vector4 pos3 = wvpM.Transpose() * new Vector4(0f, 15f, 15f, 1); Does the multiplication process change depending on whether the matrices are row or column major, or is it just the order (for an equivalent effect?) One thing that isn't helping this become any clearer, is that when provided to DirectX, my column major WVP matrix is used successfully to transform vertices with the HLSL call: mul(vector,matrix) which should result in the vector being treated as row-major, so how can the column major matrix provided by my math library work?

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• Predictive firing (in a tile-based game)

  - by n00bster

  I have a (turn-based) tile-based game, in which you can shoot at entities. You can move around with mouse and keyboard, it's all tile-based, except that bullets move "freely". I've got it all working just fine except that when I move, and the creatures shoot towards the player, they shoot towards the previous tiles.. resulting in ugly looking "miss hits" or lag. I think I need to implement some kind of predictive firing based on the bullet speed and the distance, but I don't quite know how to implement such a thing... Here's a simplified snip of my firing code. class Weapon { public void fire(int x, int y) { ... ... ... Creature owner = getOwner(); Tile targetTile = Zone.getTileAt(x, y); float dist = Vector.distance(owner.getCenterPosition(), targetTile.getCenterPosition()); Bullet b = new Bullet(); b.setPosition(owner.getCenterPosition()); // Take dist into account in the duration to get constant speed regardless of distance float duration = dist / 600f; // Moves the bullet to the centre of the target tile in the given amount of time (in seconds) b.moveTo(targetTile.getCenterPosition(), duration); // This is what I'm after // Vector v = predict the position // b.moveTo(v, duration); Zone.add(bullet); // Now the bullet gets "ticked" and moveTo will be implemented } } Movement of creatures is as simple as setting the position variable. If you need more information, just ask.

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• What is the best way to store a table in C++

  - by Topo

  I'm programming a decision tree in C++ using a slightly modified version of the C4.5 algorithm. Each node represents an attribute or a column of your data set and it has a children per possible value of the attribute. My problem is how to store the training data set having in mind that I have to use a subset for each node so I need a quick way to only select a subset of rows and columns. The main goal is to do it in the most memory and time efficient possible (in that order of priority). The best way I have thought of is to have an array of arrays (or std::vector), or something like that, and for each node have a list (array, vector, etc) or something with the column,line(probably a tuple) pairs that are valid for that node. I now there should be a better way to do this, any suggestions? UPDATE: What I need is something like this: In the beginning I have this data: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False But for the second node I just need this data: Paris 4 5.0 New York 7 1.3 Paris 9 6.8 And for the third node: Tokio 2 9.1 Tokio 0 8.4 But with a table of millions of records with up to hundreds of columns. What I have in mind is keep all the data in a matrix, and then for each node keep the info of the current columns and rows. Something like this: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False Node 2: columns = [0,1,2] rows = [0,1,3] Node 3: columns = [0,1,2] rows = [2,4] This way on the worst case scenario I just have to waste size_of(int) * (number_of_columns + number_of_rows) * node That is a lot less than having an independent data matrix for each node.

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• Rotating a sprite to touch

  - by user1691659

  I know this has been asked before and Ive looked through peoples questions and answers all over the internet and I just cant get it to work. Im sure its down to my inexperience. Ive got an arrow attached to a sprite, this sprite appears when touched but I want the arrow to point where the sprite will launch. I have had the arrow moving but it was very erratic and not pointing as it should. Its not moving at the moment but this is what I have. - (void)update:(ccTime)delta { arrow.rotation = dialRotation; } -(void) ccTouchMoved:(UITouch*)touch withEvent:(UIEvent *)event { pt1 = [self convertTouchToNodeSpace:touch]; CGPoint firstVector = ccpSub(pt, arrow.position); CGFloat firstRotateAngle = -ccpToAngle(firstVector); CGFloat previousTouch = CC_RADIANS_TO_DEGREES(firstRotateAngle); CGPoint vector = ccpSub(pt1, arrow.position); CGFloat rotateAngle = -ccpToAngle(vector); CGFloat currentTouch = CC_RADIANS_TO_DEGREES(rotateAngle); dialRotation += currentTouch - previousTouch; } I have got pt from ccTouchBegan the same way as pt1 Thanks

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• Opengl problem with texture in model from obj

  - by subSeven

  Hello! I writing small program in OpenGL, and I have problem ( textures are skew, and I dont know why, this model work in another obj viewer) What I have: http://img696.imageshack.us/i/obrazo.png/ What I want http://img88.imageshack.us/i/obraz2d.jpg/ This code where I load texture: bool success; ILuint texId; GLuint image; ilGenImages(1, &texId); ilBindImage(texId); success = ilLoadImage((WCHAR*)fileName.c_str()); if(success) { success = ilConvertImage(IL_RGB, IL_UNSIGNED_BYTE); if(!success) { return false; } } else { return false; } glGenTextures(1, &image); glBindTexture(GL_TEXTURE_2D, image); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, ilGetInteger(IL_IMAGE_BPP), ilGetInteger(IL_IMAGE_WIDTH), ilGetInteger(IL_IMAGE_HEIGHT), 0, ilGetInteger(IL_IMAGE_FORMAT), GL_UNSIGNED_BYTE, ilGetData()); ilDeleteImages(1, &texId); Code to load obj: triangles.clear(); std::ifstream in; std::string cmd; in.open (fileName.c_str()); if (in.is_open()) { while(!in.eof()) { in>>cmd; if(cmd=="v") { Vector3d vector; in>>vector.x; in>>vector.y; in>>vector.z; points.push_back(vector); } if(cmd=="vt") { Vector2d texcord; in>>texcord.x; in>>texcord.y; texcords.push_back(texcord); } if(cmd=="vn") { Vector3d normal; in>>normal.x; in>>normal.y; in>>normal.z; normals.push_back(normal); } if(cmd=="f") { Triangle triangle; std::string str; std::string str1,str2,str3; std::string delimeter("/"); int pos; int n; std::stringstream ss (std::stringstream::in | std::stringstream::out); in>>str; pos = str.find(delimeter); str1 = str.substr(0,pos); str2 = str.substr(pos+delimeter.length()); pos = str2.find(delimeter); str3 = str2.substr(pos+delimeter.length()); str2 = str2.substr(0,pos); ss<<str1; ss>>n; triangle.a= n-1; ss.clear(); ss<<str3; ss>>n; triangle.an =n-1; ss.clear(); ss<<str2; ss>>n; ss.clear(); triangle.atc = n-1; in>>str; pos = str.find(delimeter); str1 = str.substr(0,pos); str2 = str.substr(pos+delimeter.length()); pos = str2.find(delimeter); str3 = str2.substr(pos+delimeter.length()); str2 = str2.substr(0,pos); ss<<str1; ss>>n; triangle.b= n-1; ss.clear(); ss<<str3; ss>>n; triangle.bn =n-1; ss.clear(); ss<<str2; ss>>n; ss.clear(); triangle.btc = n-1; in>>str; pos = str.find(delimeter); str1 = str.substr(0,pos); str2 = str.substr(pos+delimeter.length()); pos = str2.find(delimeter); str3 = str2.substr(pos+delimeter.length()); str2 = str2.substr(0,pos); ss<<str1; ss>>n; triangle.c= n-1; ss.clear(); ss<<str3; ss>>n; triangle.cn =n-1; ss.clear(); ss<<str2; ss>>n; ss.clear(); triangle.ctc = n-1; triangles.push_back(triangle); } cmd = ""; } in.close(); return true; } return false; Code to draw model: glEnable(GL_TEXTURE_2D); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glBindTexture(GL_TEXTURE_2D,image); glBegin(GL_TRIANGLES); for(int i=0;i<triangles.size();i++) { glTexCoord2f(texcords[triangles[i].ctc].x, texcords[triangles[i].ctc].y); glNormal3f(normals[triangles[i].cn].x, normals[triangles[i].cn].y, normals[triangles[i].cn].z); glVertex3f( points[triangles[i].c].x, points[triangles[i].c].y, points[triangles[i].c].z); glTexCoord2f(texcords[triangles[i].btc].x, texcords[triangles[i].btc].y); glNormal3f(normals[triangles[i].bn].x, normals[triangles[i].bn].y, normals[triangles[i].bn].z); glVertex3f( points[triangles[i].b].x, points[triangles[i].b].y, points[triangles[i].b].z); glTexCoord2f(texcords[triangles[i].atc].x, texcords[triangles[i].atc].y); glNormal3f(normals[triangles[i].an].x, normals[triangles[i].an].y, normals[triangles[i].an].z); glVertex3f( points[triangles[i].a].x, points[triangles[i].a].y, points[triangles[i].a].z); } glEnd(); glDisable(GL_TEXTURE_2D); Mayby someone find mistake in this

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• NET Math Libraries

  - by JoshReuben

  NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

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• Level of detail algorithm not functioning correctly

  - by Darestium

  I have been working on this problem for months; I have been creating Planet Generator of sorts, after more than 6 months of work I am no closer to finishing it then I was 4 months ago. My problem; The terrain does not subdivide in the correct locations properly, it almost seems as if there is a ghost camera next to me, and the quads subdivide based on the position of this "ghost camera". Here is a video of the broken program: http://www.youtube.com/watch?v=NF_pHeMOju8 The best example of the problem occurs around 0:36. For detail limiting, I am going for a chunked LOD approach, which subdivides the terrain based on how far you are away from it. I use a "depth table" to determine how many subdivisions should take place. void PQuad::construct_depth_table(float distance) { tree[0] = -1; for (int i = 1; i < MAX_DEPTH; i++) { tree[i] = distance; distance /= 2.0f; } } The chuncked LOD relies on the child/parent structure of quads, the depth is determined by a constant e.g: if the constant is 6, there are six levels of detail. The quads which should be drawn go through a distance test from the player to the centre of the quad. void PQuad::get_recursive(glm::vec3 player_pos, std::vector<PQuad*>& out_children) { for (size_t i = 0; i < children.size(); i++) { children[i].get_recursive(player_pos, out_children); } if (this->should_draw(player_pos) || this->depth == 0) { out_children.emplace_back(this); } } bool PQuad::should_draw(glm::vec3 player_position) { float distance = distance3(player_position, centre); if (distance < tree[depth]) { return true; } return false; } The root quad has four children which could be visualized like the following: [] [] [] [] Where each [] is a child. Each child has the same amount of children up until the detail limit, the quads which have are 6 iterations deep are leaf nodes, these nodes have no children. Each node has a corresponding Mesh, each Mesh structure has 16x16 Quad-shapes, each Mesh's Quad-shapes halves in size each detail level deeper - creating more detail. void PQuad::construct_children() { // Calculate the position of the Quad based on the parent's location calculate_position(); if (depth < (int)MAX_DEPTH) { children.reserve((int)NUM_OF_CHILDREN); for (int i = 0; i < (int)NUM_OF_CHILDREN; i++) { children.emplace_back(PQuad(this->face_direction, this->radius)); PQuad *child = &children.back(); child->set_depth(depth + 1); child->set_child_index(i); child->set_parent(this); child->construct_children(); } } else { leaf = true; } } The following function creates the vertices for each quad, I feel that it may play a role in the problem - I just can't determine what is causing the problem. void PQuad::construct_vertices(std::vector<glm::vec3> *vertices, std::vector<Color3> *colors) { vertices->reserve(quad_width * quad_height); for (int y = 0; y < quad_height; y++) { for (int x = 0; x < quad_width; x++) { switch (face_direction) { case YIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, quad_height - 1.0f, -(position.y + y * element_width))); break; case YDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, 0.0f, -(position.y + y * element_width))); break; case XIncreasing: vertices->emplace_back(glm::vec3(quad_width - 1.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case XDecreasing: vertices->emplace_back(glm::vec3(0.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case ZIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, 0.0f)); break; case ZDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, -(quad_width - 1.0f))); break; } // Position the bottom, right, front vertex of the cube from being (0,0,0) to (-16, -16, 16) (*vertices)[vertices->size() - 1] -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); colors->emplace_back(Color3(255.0f, 255.0f, 255.0f, false)); } } switch (face_direction) { case YIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, quad_height - 1.0f, -(position.y + quad_height / 2.0f)); break; case YDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, 0.0f, -(position.y + quad_height / 2.0f)); break; case XIncreasing: this->centre = glm::vec3(quad_width - 1.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case XDecreasing: this->centre = glm::vec3(0.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case ZIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, 0.0f); break; case ZDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, -(quad_height - 1.0f)); break; } this->centre -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); } Any help in discovering what is causing this "subdivding in the wrong place" would be greatly appreciated.

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• C++ strongly typed typedef

  - by Kian

  I've been trying to think of a way of declaring strongly typed typedefs, to catch a certain class of bugs in the compilation stage. It's often the case that I'll typedef an int into several types of ids, or a vector to position or velocity: typedef int EntityID; typedef int ModelID; typedef Vector3 Position; typedef Vector3 Velocity; This can make the intent of code more clear, but after a long night of coding one might make silly mistakes like comparing different kinds of ids, or adding a position to a velocity perhaps. EntityID eID; ModelID mID; if ( eID == mID ) // <- Compiler sees nothing wrong { /*bug*/ } Position p; Velocity v; Position newP = p + v; // bug, meant p + v*s but compiler sees nothing wrong Unfortunately, suggestions I've found for strongly typed typedefs include using boost, which at least for me isn't a possibility (I do have c++11 at least). So after a bit of thinking, I came upon this idea, and wanted to run it by someone. First, you declare the base type as a template. The template parameter isn't used for anything in the definition, however: template < typename T > class IDType { unsigned int m_id; public: IDType( unsigned int const& i_id ): m_id {i_id} {}; friend bool operator==<T>( IDType<T> const& i_lhs, IDType<T> const& i_rhs ); }; Friend functions actually need to be forward declared before the class definition, which requires a forward declaration of the template class. We then define all the members for the base type, just remembering that it's a template class. Finally, when we want to use it, we typedef it as: class EntityT; typedef IDType<EntityT> EntityID; class ModelT; typedef IDType<ModelT> ModelID; The types are now entirely separate. Functions that take an EntityID will throw a compiler error if you try to feed them a ModelID instead, for example. Aside from having to declare the base types as templates, with the issues that entails, it's also fairly compact. I was hoping anyone had comments or critiques about this idea? One issue that came to mind while writing this, in the case of positions and velocities for example, would be that I can't convert between types as freely as before. Where before multiplying a vector by a scalar would give another vector, so I could do: typedef float Time; typedef Vector3 Position; typedef Vector3 Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; With my strongly typed typedef I'd have to tell the compiler that multypling a Velocity by a Time results in a Position. class TimeT; typedef Float<TimeT> Time; class PositionT; typedef Vector3<PositionT> Position; class VelocityT; typedef Vector3<VelocityT> Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; // Compiler error To solve this, I think I'd have to specialize every conversion explicitly, which can be kind of a bother. On the other hand, this limitation can help prevent other kinds of errors (say, multiplying a Velocity by a Distance, perhaps, which wouldn't make sense in this domain). So I'm torn, and wondering if people have any opinions on my original issue, or my approach to solving it.

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• build error with boost spirit grammar (boost 1.43 and g++ 4.4.1)

  - by lurscher

  I'm having issues getting a small spirit/qi grammar to compile. The build stack trace is fugly enought to not make any sense to me (despite some assertion_failed i could notice in there but that didn't brought much information) the input grammar header: inputGrammar.h #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_fusion.hpp> #include <boost/spirit/include/phoenix_stl.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/variant/recursive_variant.hpp> #include <boost/foreach.hpp> #include <iostream> #include <fstream> #include <string> #include <vector> namespace sp = boost::spirit; namespace qi = boost::spirit::qi; using namespace boost::spirit::ascii; //using namespace boost::spirit::arg_names; namespace fusion = boost::fusion; namespace phoenix = boost::phoenix; using phoenix::at_c; using phoenix::push_back; template< typename Iterator , typename ExpressionAST > struct InputGrammar : qi::grammar<Iterator, ExpressionAST(), space_type> { InputGrammar() : InputGrammar::base_type( block ) { tag = sp::lexeme[+(alpha) [sp::_val += sp::_1]];//[+(char_ - '<') [_val += _1]]; block = sp::lit("block") [ at_c<0>(sp::_val) = sp::_1] >> "(" >> *instruction[ push_back( at_c<1>(sp::_val) , sp::_1 ) ] >> ")"; command = tag [ at_c<0>(sp::_val) = sp::_1] >> "(" >> *instruction [ push_back( at_c<1>(sp::_val) , sp::_1 )] >> ")"; instruction = ( command | tag ) [sp::_val = sp::_1]; } qi::rule< Iterator , std::string() , space_type > tag; qi::rule< Iterator , ExpressionAST() , space_type > block; qi::rule< Iterator , ExpressionAST() , space_type > function_def; qi::rule< Iterator , ExpressionAST() , space_type > command; qi::rule< Iterator , ExpressionAST() , space_type > instruction; }; the test build program: i seems the build fails at qi::phrase_parse, i am using boost 1.43 and g++ 4.4.1 #include <iostream> #include <string> #include <vector> using namespace std; //my grammar #include <InputGrammar.h> struct MockExpressionNode { std::string name; std::vector< MockExpressionNode > operands; typedef std::vector< MockExpressionNode >::iterator iterator; typedef std::vector< MockExpressionNode >::const_iterator const_iterator; iterator begin() { return operands.begin(); } const_iterator begin() const { return operands.begin(); } iterator end() { return operands.end(); } const_iterator end() const { return operands.end(); } bool is_leaf() const { return ( operands.begin() == operands.end() ); } }; BOOST_FUSION_ADAPT_STRUCT( MockExpressionNode, (std::string, name) (std::vector<MockExpressionNode>, operands) ) int const tabsize = 4; void tab(int indent) { for (int i = 0; i < indent; ++i) std::cout << ' '; } template< typename ExpressionNode > struct ExpressionNodePrinter { ExpressionNodePrinter(int indent = 0) : indent(indent) { } void operator()(ExpressionNode const& node) const { cout << " tag: " << node.name << endl; for (int i=0 ; i < node.operands.size() ; i++ ) { tab( indent ); cout << " arg "<<i<<": "; ExpressionNodePrinter(indent + 2)( node.operands[i]); cout << endl; } } int indent; }; int test() { MockExpressionNode root; InputGrammar< string::const_iterator , MockExpressionNode > g(); std::string litA = "litA"; std::string litB = "litB"; std::string litC = "litC"; std::string litD = "litD"; std::string litE = "litE"; std::string litF = "litF"; std::string source = litA+"( "+litB+" ,"+litC+" , "+ litD+" ( "+litE+", "+litF+" ) "+ " )"; string::const_iterator iter = source.begin(); string::const_iterator end = source.end(); bool r = qi::phrase_parse( iter , end , g , root , space ); ExpressionNodePrinter< MockExpressionNode > np; np( root ); }; int main() { test(); } finally, the build error is the following: /usr/bin/make -f nbproject/Makefile-linux_amd64_devel.mk SUBPROJECTS= .build-conf make[1]: se ingresa al directorio `/home/mineq/NetBeansProjects/InputParserTests' /usr/bin/make -f nbproject/Makefile-linux_amd64_devel.mk dist/linux_amd64_devel/GNU-Linux-x86/vpuinputparsertests make[2]: se ingresa al directorio `/home/mineq/NetBeansProjects/InputParserTests' mkdir -p build/linux_amd64_devel/GNU-Linux-x86 rm -f build/linux_amd64_devel/GNU-Linux-x86/tests_main.o.d g++ `llvm-config --cxxflags` `pkg-config --cflags unittest-cpp` `pkg-config --cflags boost-1.43` `pkg-config --cflags boost-coroutines` -c -g -I../InputParser -MMD -MP -MF build/linux_amd64_devel/GNU-Linux-x86/tests_main.o.d -o build/linux_amd64_devel/GNU-Linux-x86/tests_main.o tests_main.cpp from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:16, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp: In function ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/detail/parse_auto.hpp:14, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:99: error: no matching function for call to ‘assertion_failed(mpl_::failed************ (boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::error_invalid_expression::************)(InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (*)()))’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:100: error: no matching function for call to ‘assertion_failed(mpl_::failed************ (boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::error_invalid_expression::************)(MockExpressionNode))’ from /home/mineq/third_party/boost_1_43_0/boost/proto/proto.hpp:12, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/support/meta_compiler.hpp:17, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/meta_compiler.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/action/action.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/action.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:14, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/proto/detail/expr0.hpp: At global scope: /home/mineq/third_party/boost_1_43_0/boost/proto/proto_fwd.hpp: In instantiation of ‘boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>’: In file included from /home/mineq/third_party/boost_1_43_0/boost/proto/core.hpp:13, /home/mineq/third_party/boost_1_43_0/boost/utility/enable_if.hpp:59: instantiated from ‘boost::disable_if<boost::proto::result_of::is_expr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>, void>, void>’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/support/meta_compiler.hpp:200: instantiated from ‘boost::spirit::result_of::compile<boost::spirit::qi::domain, InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), boost::fusion::unused_type, void>’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:107: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/proto/detail/expr0.hpp:64: error: field ‘boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()>, 0l>::child0’ invalidly declared function type from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:16, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp: In function ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/detail/parse_auto.hpp:14, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:107: error: request for member ‘parse’ in ‘boost::spirit::compile [with Domain = boost::spirit::qi::domain, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()](((InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (&)())((InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode> (*)())expr)))’, which is of non-class type ‘InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>()’ from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi.hpp:15, from /home/mineq/third_party/boost_1_43_0/boost/spirit/include/qi.hpp:16, from ../InputParser/InputGrammar.h:12, from tests_main.cpp:14: /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/skip_over.hpp: In function ‘void boost::spirit::qi::skip_over(Iterator&, const Iterator&, const T&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, T = boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]::skipper_type]’: In file included from /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/auto/auto.hpp:19, /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:112: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>]’ /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/parse.hpp:125: instantiated from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, Expr = InputGrammar<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, MockExpressionNode>(), Skipper = MockExpressionNode, Attr = const boost::spirit::ascii::space_type]’ tests_main.cpp:206: instantiated from here /home/mineq/third_party/boost_1_43_0/boost/spirit/home/qi/skip_over.hpp:27: error: ‘const struct MockExpressionNode’ has no member named ‘parse’ make[2]: *** [build/linux_amd64_devel/GNU-Linux-x86/tests_main.o] Error 1 make[2]: se sale del directorio `/home/mineq/NetBeansProjects/InputParserTests' make[1]: *** [.build-conf] Error 2 make[1]: se sale del directorio `/home/mineq/NetBeansProjects/InputParserTests' make: *** [.build-impl] Error 2 BUILD FAILED (exit value 2, total time: 1m 48s)

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• Ball to Ball Collision - Detection and Handling

  - by Simucal

  With the help of the Stack Overflow community I've written a pretty basic-but fun physics simulator. You click and drag the mouse to launch a ball. It will bounce around and eventually stop on the "floor". My next big feature I want to add in is ball to ball collision. The ball's movement is broken up into a x and y speed vector. I have gravity (small reduction of the y vector each step), I have friction (small reduction of both vectors each collision with a wall). The balls honestly move around in a surprisingly realistic way. I guess my question has two parts: What is the best method to detect ball to ball collision? Do I just have an O(n^2) loop that iterates over each ball and checks every other ball to see if it's radius overlaps? What equations do I use to handle the ball to ball collisions? Physics 101 How does it effect the two balls speed x/y vectors? What is the resulting direction the two balls head off in? How do I apply this to each ball? Handling the collision detection of the "walls" and the resulting vector changes were easy but I see more complications with ball-ball collisions. With walls I simply had to take the negative of the appropriate x or y vector and off it would go in the correct direction. With balls I don't think it is that way. Some quick clarifications: for simplicity I'm ok with a perfectly elastic collision for now, also all my balls have the same mass right now, but I might change that in the future. In case anyone is interested in playing with the simulator I have made so far, I've uploaded the source here (EDIT: Check the updated source below). Edit: Resources I have found useful 2d Ball physics with vectors: 2-Dimensional Collisions Without Trigonometry.pdf 2d Ball collision detection example: Adding Collision Detection Success! I have the ball collision detection and response working great! Relevant code: Collision Detection: for (int i = 0; i < ballCount; i++) { for (int j = i + 1; j < ballCount; j++) { if (balls[i].colliding(balls[j])) { balls[i].resolveCollision(balls[j]); } } } This will check for collisions between every ball but skip redundant checks (if you have to check if ball 1 collides with ball 2 then you don't need to check if ball 2 collides with ball 1. Also, it skips checking for collisions with itself). Then, in my ball class I have my colliding() and resolveCollision() methods: public boolean colliding(Ball ball) { float xd = position.getX() - ball.position.getX(); float yd = position.getY() - ball.position.getY(); float sumRadius = getRadius() + ball.getRadius(); float sqrRadius = sumRadius * sumRadius; float distSqr = (xd * xd) + (yd * yd); if (distSqr <= sqrRadius) { return true; } return false; } public void resolveCollision(Ball ball) { // get the mtd Vector2d delta = (position.subtract(ball.position)); float d = delta.getLength(); // minimum translation distance to push balls apart after intersecting Vector2d mtd = delta.multiply(((getRadius() + ball.getRadius())-d)/d); // resolve intersection -- // inverse mass quantities float im1 = 1 / getMass(); float im2 = 1 / ball.getMass(); // push-pull them apart based off their mass position = position.add(mtd.multiply(im1 / (im1 + im2))); ball.position = ball.position.subtract(mtd.multiply(im2 / (im1 + im2))); // impact speed Vector2d v = (this.velocity.subtract(ball.velocity)); float vn = v.dot(mtd.normalize()); // sphere intersecting but moving away from each other already if (vn > 0.0f) return; // collision impulse float i = (-(1.0f + Constants.restitution) * vn) / (im1 + im2); Vector2d impulse = mtd.multiply(i); // change in momentum this.velocity = this.velocity.add(impulse.multiply(im1)); ball.velocity = ball.velocity.subtract(impulse.multiply(im2)); } Source Code: Complete source for ball to ball collider. Binary: Compiled binary in case you just want to try bouncing some balls around. If anyone has some suggestions for how to improve this basic physics simulator let me know! One thing I have yet to add is angular momentum so the balls will roll more realistically. Any other suggestions? Leave a comment!

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• BOOST program_options: parsing multiple argument list.

  - by Arman

  Hello, I would like to pass the multiple arguments with positive or negative values. Is it possible to parse it? Currently I have a following initialization: vector<int> IDlist; namespace po = boost::program_options; po::options_description commands("Allowed options"); commands.add_options() ("IDlist",po::value< vector<int> >(&IDlist)->multitoken(), "Which IDs to trace: ex. --IDlist=0 1 200 -2") ("help","print help") ; and I would like to call: ./test_ids.x --IDlist=0 1 200 -2 unknown option -2 So,the program_options assumes that I am passing -2 as an another option. Can I configure the program_options in such a way that it can accept the negative integer values? Thanks Arman.

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• Extracting, then passing raw data into another class - How to avoid copying twice while maintaining

  - by Kache4

  Consider a class Book with a stl container of class Page. each Page holds a screenshot, like page10.jpg in raw vector<char> form. A Book is opened with a path to a zip, rar, or directory containing these screenshots, and uses respective methods of extracting the raw data, like ifstream inFile.read(buffer, size);, or unzReadCurrentFile(zipFile, buffer, size). It then calls the Page(const char* stream, int filesize) constructor. Right now, it's clear that the raw data is being copied twice. Once to extract to Book's local buffer and a second time in the Page ctor to the Page::vector<char>. Is there a way to maintain encapsulation while getting rid of the middleman buffer?

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• Python: Implementing slicing in __getitem__

  - by nicotine

  I am trying to implement slice functionality for a class I am making that creates a vector representation. I have this code so far, which I believe will properly implement the slice but whenever I do a call like v[4] where v is a vector python returns an error about not having enough parameters. So I am trying to figure out how to define the getitem class to handle both plain indexes and slicing. def __getitem__(self, start, stop, step): indx = start if stop == None: end = start + 1 else: end = stop if step == None: stride = 1 else: stride = step return self.__data[indx:end:stride]

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• iPhone – Best method to import/drawing UI graphic elements? CGContextDrawPDFPage?

  - by Ross

  Hello, What is the best way to use the custom UI graphics on the iPhone? I've come across CGContextDrawPDFPage and Panic's Shrinkit. Should I be using storing my vector ui graphics as PDF's and loading them using CGContextDrawPDFPage to draw them. I did previously asked what way Apple store their UI graphics and was answered crushed png. The options as I see it, but I would really want to know what technique other people use. This question is for vector graphics only. Looking for what is standard / most effective / most efficient. PNG (bitmapped image) Custom UIView drawing code (generated from Opacity) PDF (I've not used this method, is it with CGContextDrawPDFPage?) Many thanks Ross

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• Alpha Beta Search

  - by Becky

  I'm making a version of Martian Chess in java with AI and so far I THINK my move searching is semi-working, it seems to work alright for some depths but if I use a depth of 3 it returns a move for the opposite side...now the game is a bit weird because when a piece crosses half of the board, it becomes property of the other player so I think this is part of the problem. I'd be really greatful if someone could look over my code and point out any errors you think are there! (pls note that my evaluation function isn't nearly complete lol) MoveSearch.java public class MoveSearch { private Evaluation evaluate = new Evaluation(); private int blackPlayerScore, whitePlayerScore; public MoveContent bestMove; public MoveSearch(int blackScore, int whiteScore) { blackPlayerScore = blackScore; whitePlayerScore = whiteScore; } private Vector<Position> EvaluateMoves(Board board) { Vector<Position> positions = new Vector<Position>(); for (int i = 0; i < 32; i++) { Piece piece = null; if (!board.chessBoard[i].square.isEmpty()) { // store the piece piece = board.chessBoard[i].square.firstElement(); } // skip empty squares if (piece == null) { continue; } // skip the other players pieces if (piece.pieceColour != board.whosMove) { continue; } // generate valid moves for the piece PieceValidMoves validMoves = new PieceValidMoves(board.chessBoard, i, board.whosMove); validMoves.generateMoves(); // for each valid move for (int j = 0; j < piece.validMoves.size(); j++) { // store it as a position Position move = new Position(); move.startPosition = i; move.endPosition = piece.validMoves.elementAt(j); Piece pieceAttacked = null; if (!board.chessBoard[move.endPosition].square.isEmpty()) { // if the end position is not empty, store the attacked piece pieceAttacked = board.chessBoard[move.endPosition].square.firstElement(); } // if a piece is attacked if (pieceAttacked != null) { // append its value to the move score move.score += pieceAttacked.pieceValue; // if the moving pieces value is less than the value of the attacked piece if (piece.pieceValue < pieceAttacked.pieceValue) { // score extra points move.score += pieceAttacked.pieceValue - piece.pieceValue; } } // add the move to the set of positions positions.add(move); } } return positions; } // EvaluateMoves() private int SideToMoveScore(int score, PieceColour colour) { if (colour == PieceColour.Black){ return -score; } else { return score; } } public int AlphaBeta(Board board, int depth, int alpha, int beta) { //int best = -9999; // if the depth is 0, return the score of the current board if (depth <= 0) { board.printBoard(); System.out.println("Score: " + evaluate.EvaluateBoardScore(board)); System.out.println(""); int boardScore = evaluate.EvaluateBoardScore(board); return SideToMoveScore(boardScore, board.whosMove); } // fill the positions with valid moves Vector<Position> positions = EvaluateMoves(board); // if there are no available positions if (positions.size() == 0) { // and its blacks move if (board.whosMove == PieceColour.Black) { if (blackPlayerScore > whitePlayerScore) { // and they are winning, return a high number return 9999; } else if (whitePlayerScore == blackPlayerScore) { // if its a draw, lower number return 500; } else { // if they are losing, return a very low number return -9999; } } if (board.whosMove == PieceColour.White) { if (whitePlayerScore > blackPlayerScore) { return 9999; } else if (blackPlayerScore == whitePlayerScore) { return 500; } else { return -9999; } } } // for each position for (int i = 0; i < positions.size(); i++) { // store the position Position move = positions.elementAt(i); // temporarily copy the board Board temp = board.copyBoard(board); // make the move temp.makeMove(move.startPosition, move.endPosition); for (int x = 0; x < 32; x++) { if (!temp.chessBoard[x].square.isEmpty()) { PieceValidMoves validMoves = new PieceValidMoves(temp.chessBoard, x, temp.whosMove); validMoves.generateMoves(); } } // repeat the process recursively, decrementing the depth int val = -AlphaBeta(temp, depth - 1, -beta, -alpha); // if the value returned is better than the current best score, replace it if (val >= beta) { // beta cut-off return beta; } if (val > alpha) { alpha = val; bestMove = new MoveContent(alpha, move.startPosition, move.endPosition); } } // return the best score return alpha; } // AlphaBeta() } This is the makeMove method public void makeMove(int startPosition, int endPosition) { // quick reference to selected piece and attacked piece Piece selectedPiece = null; if (!(chessBoard[startPosition].square.isEmpty())) { selectedPiece = chessBoard[startPosition].square.firstElement(); } Piece attackedPiece = null; if (!(chessBoard[endPosition].square.isEmpty())) { attackedPiece = chessBoard[endPosition].square.firstElement(); } // if a piece is taken, amend score if (!(chessBoard[endPosition].square.isEmpty()) && attackedPiece != null) { if (attackedPiece.pieceColour == PieceColour.White) { blackScore = blackScore + attackedPiece.pieceValue; } if (attackedPiece.pieceColour == PieceColour.Black) { whiteScore = whiteScore + attackedPiece.pieceValue; } } // actually move the piece chessBoard[endPosition].square.removeAllElements(); chessBoard[endPosition].addPieceToSquare(selectedPiece); chessBoard[startPosition].square.removeAllElements(); // changing piece colour based on position if (endPosition > 15) { selectedPiece.pieceColour = PieceColour.White; } if (endPosition <= 15) { selectedPiece.pieceColour = PieceColour.Black; } //change to other player if (whosMove == PieceColour.Black) whosMove = PieceColour.White; else if (whosMove == PieceColour.White) whosMove = PieceColour.Black; } // makeMove()

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• Updating / refreshing a live geojson layer | JSON & JS Variable

  - by Ozaki

  TLDR I am trying to get my geoJSON layer to update, currently it will 1. Create the vector mark, 2. Remove the vector mark, 3. Set the JS variable for lat and lon, 4. Unset the variable??? :S Hey S O. I have a geojson layer set up as follows: //GeoJSON Layer// var layer1 = new OpenLayers.Layer.GML("My GeoJSON Layer", "coordinates", {format: OpenLayers.Format.GeoJSON, styleMap: style_red}); My features are set up as follows: var latitude = 0.0; // as 0.0 it will draw the point in. var longitude = 0.0; // as 0.0 it will draw the point in. //var longitude = getlongitude; where getlongitude = JSON string of longitude. var point = new OpenLayers.Geometry.Point(longitude, latitude); pointFeature = new OpenLayers.Feature.Vector(point, null, style_red); var style_red = OpenLayers.Util.extend({}, layer_style); style_red.strokeColor = "red"; style_red.fillColor = "black"; style_red.fillOpacity = 0.5; style_red.graphicName = "circle"; style_red.pointRadius = 3.8; style_red.strokeWidth = 2; style_red.strokeLinecap = "butt"; and my layer updating function: function UpdateLayer(){ var p = new OpenLayers.Format.GeoJSON({ 'internalProjection': new OpenLayers.Projection("EPSG:900913"), 'externalProjection': new OpenLayers.Projection("EPSG:4326") }); var url = "coordinates"; OpenLayers.loadURL(url, {}, null, function(r) { var f = p.read(r.responseText); map.layers[2].destroyFeatures(); map.layers[2].addFeatures(pointFeature); }); setTimeout("UpdateLayer()",1000) } Any idea what I am doing wrong or what I am missing? Edit1 It now removes the feature (was map.layers[1]) previously... But will not add the new feature.. Edit2 I managed to get it to redraw a point but not with live data. It should draw the point at what (latitude) & (longitude) are equal to. I am trying to set latitude & longitude to some JSON string but every time straight after it sets the variable it changes it back to "undefined" as soon as it passes the line after var latitude? (using firebug & firequery to debug)

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• Seg Fault when using std::string on an embedded Linux platform

  - by Brad

  Hi, I have been working for a couple of days on a problem with my application running on an embedded Arm Linux platform. Unfortunately the platform precludes me from using any of the usual useful tools for finding the exact issue. When the same code is run on the PC running Linux, I get no such error. In the sample below, I can reliably reproduce the problem by uncommenting the string, list or vector lines. Leaving them commented results in the application running to completion. I expect that something is corrupting the heap, but I cannot see what? The program will run for a few seconds before giving a segmentation fault. The code is compiled using a arm-linux cross compiler: arm-linux-g++ -Wall -otest fault.cpp -ldl -lpthread arm-linux-strip test Any ideas greatly appreciated. #include <stdio.h> #include <vector> #include <list> #include <string> using namespace std; ///////////////////////////////////////////////////////////////////////////// class TestSeg { static pthread_mutex_t _logLock; public: TestSeg() { } ~TestSeg() { } static void* TestThread( void *arg ) { int i = 0; while ( i++ < 10000 ) { printf( "%d\n", i ); WriteBad( "Function" ); } pthread_exit( NULL ); } static void WriteBad( const char* sFunction ) { pthread_mutex_lock( &_logLock ); printf( "%s\n", sFunction ); //string sKiller; // <----------------------------------Bad //list<char> killer; // <----------------------------------Bad //vector<char> killer; // <----------------------------------Bad pthread_mutex_unlock( &_logLock ); return; } void RunTest() { int threads = 100; pthread_t _rx_thread[threads]; for ( int i = 0 ; i < threads ; i++ ) { pthread_create( &_rx_thread[i], NULL, TestThread, NULL ); } for ( int i = 0 ; i < threads ; i++ ) { pthread_join( _rx_thread[i], NULL ); } } }; pthread_mutex_t TestSeg::_logLock = PTHREAD_MUTEX_INITIALIZER; int main( int argc, char *argv[] ) { TestSeg seg; seg.RunTest(); pthread_exit( NULL ); }

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• How can I get this code involving unique_ptr and emplace_back to compile?

  - by Neil G

  #include <vector> #include <memory> using namespace std; class A { public: A(): i(new int) {} A(A const& a) = delete; A(A &&a): i(move(a.i)) {} unique_ptr<int> i; }; class AGroup { public: void AddA(A &&a) { a_.emplace_back(move(a)); } vector<A> a_; }; int main() { AGroup ag; ag.AddA(A()); return 0; } does not compile... (says that unique_ptr's copy constructor is deleted) I tried replacing move with forward. Not sure if I did it right, but it didn't work for me.

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• Dynamically creating controls in MFC (Collection question)

  - by ProgramWriter

  Hello all, I have some custom control inside of which i should create radiobuttons or checkboxes. The count of child controls is available only at runtime (it loads some file from which it gets this count). So i need to create variable number of controls. Which collection i should use for this purpose? Solution 1: simply use std::vector (or CArray) - not suitable because i want use MFC (CButton). Of course i can Attach() and later Detach() handle to window each time i need this window, but it will give big overhead. Solution 2: use std::vector or CArray or CList or... In this case i take care about making 'new' and appropriate 'delete' when control is unneeded. I am forgetful :) MFC handle map contains pointer to CButton and i can't use simple CArray, because it will move my objects each time when his size will grow. ... and the question is: Which collection i should use for containing variable count of MFC control classes?

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• Code coverage (c++ code execution path)

  - by Poni

  Let's say I have this code: int function(bool b) { // execution path 1 int ret = 0; if(b) { // execution path 2 ret = 55; } else { // execution path 3 ret = 120; } return ret; } I need some sort of a mechanism to make sure that the code has gone in any possible path, i.e execution paths 1, 2 & 3 in the code above. I thought about having a global function, vector and a macro. This macro would simply call that function, passing as parameters the source file name and the line of code, and that function would mark that as "checked", by inserting to the vector the info that the macro passed. The problem is that I will not see anything about paths that did not "check". Any idea how do I do this? How to "register" a line of code at compile-time, so in run-time I can see that it didn't "check" yet? I hope I'm clear.

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• defining < operator for map of list iterators

  - by Adrian

  I'd like to use iterators from an STL list as keys in a map. For example: using namespace std; list<int> l; map<list<int>::const_iterator, int> t; int main(int argv, char * argc) { l.push_back(1); t[l.begin()] = 5; } However, list iterators do not have a comparison operator defined (in contrast to random access iterators), so compiling the above code results in an error: /usr/include/c++/4.2.1/bits/stl_function.h:227: error: no match for ‘operator<’ in ‘__x < __y’ If the list is changed to a vector, a map of vector const_iterators compiles fine. What is the appropriate way to define the operator < for list::const_iterator?

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