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  • Where can I find BLAS example code (in Fortran)?

    - by Feynman
    I have been searching for decent documentation on blas, and I have found some 315 pages of dense material that ctrl-f does not work on. It provides all the information regarding what input arguments the routines take, but there are a LOT of input arguments and I could really use some example code. I am unable to locate any. I know there has to be some or no one would be able to use these libraries! Specifically, I use ATLAS installed via macports on a mac osx 10.5.8 and I use gfortran from gcc 4.4 (also installed via macports). I am coding in Fortran 90. I am still quite new to Fortran, but I have a fair amount of experience with mathematica, matlab, perl, and shell scripting. I would like to be able to initialize and multiply a dense complex vector by a dense symmetric (but not hermitian) complex matrix. The elements of the matrix are defined through a mathematical function of the indices--call it f(i,j). Could anyone provide some code or a link to some code?

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  • "no inclosing instance error " while getting top term frequencies for document from Lucene index

    - by Julia
    Hello ! I am trying to get the most occurring term frequencies for every particular document in Lucene index. I am trying to set the treshold of top occuring terms that I care about, maybe 20 However, I am getting the "no inclosing instance of type DisplayTermVectors is accessible" when calling Comparator... So to this function I pass vector of every document and max top terms i would like to know protected static Collection getTopTerms(TermFreqVector tfv, int maxTerms){ String[] terms = tfv.getTerms(); int[] tFreqs = tfv.getTermFrequencies(); List result = new ArrayList(terms.length); for (int i = 0; i < tFreqs.length; i++) { TermFrq tf = new TermFrq(terms[i], tFreqs[i]); result.add(tf); } Collections.sort(result, new FreqComparator()); if(maxTerms < result.size()){ result = result.subList(0, maxTerms); } return result; } /Class for objects to hold the term/freq pairs/ static class TermFrq{ private String term; private int freq; public TermFrq(String term,int freq){ this.term = term; this.freq = freq; } public String getTerm(){ return this.term; } public int getFreq(){ return this.freq; } } /*Comparator to compare the objects by the frequency*/ class FreqComparator implements Comparator{ public int compare(Object pair1, Object pair2){ int f1 = ((TermFrq)pair1).getFreq(); int f2 = ((TermFrq)pair2).getFreq(); if(f1 > f2) return 1; else if(f1 < f2) return -1; else return 0; } } Explanations and corrections i will very much appreciate, and also if someone else had experience with term frequency extraction and did it better way, I am opened to all suggestions! Please help!!!! Thanx!

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  • STL vectors with uninitialized storage?

    - by Jim Hunziker
    I'm writing an inner loop that needs to place structs in contiguous storage. I don't know how many of these structs there will be ahead of time. My problem is that STL's vector initializes its values to 0, so no matter what I do, I incur the cost of the initialization plus the cost of setting the struct's members to their values. Is there any way to prevent the initialization, or is there an STL-like container out there with resizeable contiguous storage and uninitialized elements? (I'm certain that this part of the code needs to be optimized, and I'm certain that the initialization is a significant cost.) Also, see my comments below for a clarification about when the initialization occurs. SOME CODE: void GetsCalledALot(int* data1, int* data2, int count) { int mvSize = memberVector.size() memberVector.resize(mvSize + count); // causes 0-initialization for (int i = 0; i < count; ++i) { memberVector[mvSize + i].d1 = data1[i]; memberVector[mvSize + i].d2 = data2[i]; } }

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  • How do I declare and initialize a 2d int vector in C++?

    - by FrankTheTank
    I'm trying to do something like: #include <iostream> #include <vector> #include <ctime> class Clickomania { public: Clickomania(); std::vector<std::vector<int> > board; bool move(int, int); bool isSolved(); void print(); void pushDown(); }; Clickomania::Clickomania() : board(12, std::vector<int>(8,0)) { srand((unsigned)time(0)); for(int i = 0; i < 12; i++) { for(int j = 0; j < 8; j++) { int color = (rand() % 6) + 1; board[i][j] = color; } } } However, apparently I can't initialize the "board" vector of vectors this way. How can I create a public member of a 2d vector type and initialize it properly?

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  • Convert Markdown text to RTF, using Ruby and Pandoc?

    - by niteshade
    Playing with Ruby and Ruby-Pandoc. Seems like a nice tool, if I can get it to work. I'd like to convert some Markdown text (with embedded lists and other fanciness) to Rich Text. Here's the text I'm converting: Title === This is a paragraph. Hallelujah. Here comes a nested list. --- * List item 1 * List item 1.1 * List item 1.2 * List item 2 * List item 2.1 Here's my Ruby code... require 'pandoc-ruby' input = File.read(test.md) converter = PandocRuby.new(input, from: :markdown, to: :rtf) puts converter.convert ... which (after saving the output to a file) produces a document without anything but a title: Here's the code of the RTF file: {\pard \ql \f0 \sa180 \li0 \fi0 \b \fs36 Title\par} {\pard \ql \f0 \sa180 \li0 \fi0 This is a paragraph. Hallelujah.\par} {\pard \ql \f0 \sa180 \li0 \fi0 \b \fs32 Here comes a nested list.\par} {\pard \ql \f0 \sa0 \li360 \fi-360 \bullet \tx360\tab List item 1\par} {\pard \ql \f0 \sa0 \li360 \fi-360 \bullet \tx360\tab List item 1.1\par} {\pard \ql \f0 \sa0 \li360 \fi-360 \bullet \tx360\tab List item 1.2\par} {\pard \ql \f0 \sa0 \li360 \fi-360 \bullet \tx360\tab List item 2\par} {\pard \ql \f0 \sa0 \li360 \fi-360 \bullet \tx360\tab List item 2.1\sa180\par} In addition, even if it did show up in my RTF viewer (Mac TextEdit), the RTF code seems to have lost all list nesting. I don't know how to diagnose this, whether I have not stated necessary header information or something in Ruby-Pandoc. Thanks in advance!

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  • Vectors or Java arrays for Tetris?

    - by StackedCrooked
    I'm trying to create a Tetris-like game with Clojure and I'm having some trouble deciding the data structure for the playing field. I want to define the playing field as a mutable grid. The individual blocks are also grids, but don't need to be mutable. My first attempt was to define a grid as a vector of vectors. For example an S-block looks like this: :s-block { :grids [ [ [ 0 1 1 ] [ 1 1 0 ] ] [ [ 1 0 ] [ 1 1 ] [ 0 1 ] ] ] } But that turns out to be rather tricky for simple things like iterating and painting (see the code below). For making the grid mutable my initial idea was to make each row a reference. But then I couldn't really figure out how to change the value of a specific cell in a row. One option would have been to create each individual cell a ref instead of each row. But that feels like an unclean approach. I'm considering using Java arrays now. Clojure's aget and aset functions will probably turn out to be much simpler. However before digging myself in a deeper mess I want to ask ideas/insights. How would you recommend implementing a mutable 2d grid? Feel free to share alternative approaches as well. Source code current state: Tetris.clj (rev452)

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  • yet another logic.

    - by Sunil
    I'm working on a research problem out of curiosity and I don't know how to program the logic that I've in mind. Let me explain it to you : I've 4 vectors say for example, v1 = 1 1 1 1 v2 = 2 2 2 2 v3 = 3 3 3 3 v4 = 4 4 4 4 Now what I want to do is to add them combination-wise. i.e v12 = v1+v2 v13 = v1+v3 v14 = v1+v4 v23 = v2+v3 v24 = v2+v4 v34 = v3+v4 Till this step it is just fine. The problem/trick is now, at the end of each iteration I give the obtained vectors into a black box function and it returns only few of the vectors say v12, v13 and v34. Now, I want to add each of these vectors one vector from v1,v2,v3,v4 which it hasn't added before. For example v3 and v4 hasn't been added to v12 so I want to create v123 and v124. similarly for all the vectors like, v12 should become : v123 = v12+v3 v124 = v12+v4 v13 should become : v132 // this should not occur because I already have v123 v134 = v13+v4; v14,v23 and v24 cannot be considered because it was deleted in the black box function so all we have in our hands to work with is v12,v13 and v34. v34 should become : v341 // cannot occur because we have 134 v342 = v34+v2 It is important that I do not do all at one step at the start like for example I can do (4 choose 3) 4C3 and finish it off but I want to do it step by step at each iteration. I've asked a modified version of this question before (without including the black box function) and got answers here. Can anybody tell me how to do it when the black box function is included ? A modification of the previous answer would also be great. Thanks in advance.

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  • random, Graphics point ,searching- algorithm, via dual for loop set

    - by LoneXcoder
    hello and thanks for joining me in my journey to the custom made algorithm for "guess where the pixel is" this for Loop set (over Point.X, Point.Y), is formed in consecutive/linear form: //Original\initial Location Point initPoint = new Point(150, 100); // No' of pixels to search left off X , and above Y int preXsrchDepth, preYsrchDepth; // No' of pixels to search to the right of X, And Above Y int postXsrchDepth, postYsrchDepth; preXsrchDepth = 10; // will start search at 10 pixels to the left from original X preYsrchDepth = 10; // will start search at 10 pixels above the original Y postXsrchDepth = 10; // will stop search at 10 pixels to the right from X postYsrchDepth = 10; // will stop search at 10 pixels below Y int StopXsearch = initPoint.X + postXsrchDepth; //stops X Loop itarations at initial pointX + depth requested to serch right of it int StopYsearch = initPoint.Y + postYsrchDepth; //stops Y Loop itarations at initial pointY + depth requested below original location int CountDownX, CountDownY; // Optional not requierd for loop but will reports the count down how many iterations left (unless break; triggerd ..uppon success) Point SearchFromPoint = Point.Empty; //the point will be used for (int StartX = initPoint.X - preXsrchDepth; StartX < StopXsearch; StartX++) { SearchFromPoint.X = StartX; for (int StartY = initPoint.Y - preYsrchDepth; StartY < StpY; StartY++) { CountDownX = (initPoint.X - StartX); CountDownY=(initPoint.Y - StartY); SearchFromPoint.Y = StartY; if (SearchSuccess) { same = true; AAdToAppLog("Search Report For: " + imgName + "Search Completed Successfully On Try " + CountDownX + ":" + CountDownY); break; } } } <-10 ---- -5--- -1 X +1--- +5---- +10 what i would like to do is try a way of instead is have a little more clever approach <+8---+5-- -8 -5 -- +2 +10 X -2 - -10 -8-- -6 ---1- -3 | +8 | -10 Y +1 -6 | | +9 .... I do know there's a wheel already invented in this field (even a full-trailer truck amount of wheels (: ) but as a new programmer, I really wanted to start of with a simple way and also related to my field of interest in my project. can anybody show an idea of his, he learnt along the way to Professionalism in algorithm /programming having tests to do on few approaches (kind'a random cleverness...) will absolutely make the day and perhaps help some others viewing this page in the future to come it will be much easier for me to understand if you could use as much as possible similar naming to variables i used or implenet your code example ...it will be Greatly appreciated if used with my code sample, unless my metod is a realy flavorless. p.s i think that(atleast as human being) the tricky part is when throwing inconsecutive numbers you loose track of what you didn't yet use, how do u take care of this too . thanks allot in advance looking forward to your participation !

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  • What did Rich Hickey mean when he said, "All that specificity [of interfaces/classes/types] kills your reuse!"

    - by GlenPeterson
    In Rich Hickey's thought-provoking goto conference keynote "The Value of Values" at 29 minutes he's talking about the overhead of a language like Java and makes a statement like, "All those interfaces kill your reuse." What does he mean? Is that true? In my search for answers, I have run across: The Principle of Least Knowledge AKA The Law of Demeter which encourages airtight API interfaces. Wikipedia also lists some disadvantages. Kevlin Henney's Imperial Clothing Crisis which argues that use, not reuse is the appropriate goal. Jack Diederich's "Stop Writing Classes" talk which argues against over-engineering in general. Clearly, anything written badly enough will be useless. But how would the interface of a well-written API prevent that code from being used? There are examples throughout history of something made for one purpose being used more for something else. But in the software world, if you use something for a purpose it wasn't intended for, it usually breaks. I'm looking for one good example of a good interface preventing a legitimate but unintended use of some code. Does that exist? I can't picture it.

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  • Animating gradient displays line artifacts in ActionScript

    - by TheDarkIn1978
    i've programatically created a simple gradient (blue to red) sprite rect using my own basic class called GradientRect, but moving or animation the sprite exhibits line artifacts. when the sprite is rotating, it kind of resembles bad reception of an old television set. i'm almost certain the cause is because each line slice of the gradient is vector so there are gaps between the lines - this is visible when the sprite is zoomed in. var colorPickerRect:GradientRect = new GradientRect(200, 200, 0x0000FF, 0xFF0000); addChild(colorPickerRect); colorPickerRect.cacheAsBitmap = true; colorPickerRect.x = colorPickerRect.y = 100; colorPickerRect.addEventListener(Event.ENTER_FRAME, rotate); function rotate(evt:Event):void { evt.target.rotation += 1; } ________________________ //CLASS PACKAGE package { import flash.display.CapsStyle; import flash.display.GradientType; import flash.display.LineScaleMode; import flash.display.Sprite; import flash.geom.Matrix; public class GradientRect extends Sprite { public function GradientRect(gradientRectWidth:Number, gradientRectHeight:Number, ...leftToRightColors) { init(gradientRectWidth, gradientRectHeight, leftToRightColors); } private function init(gradientRectWidth:Number, gradientRectHeight:Number, leftToRightColors:Array):void { var leftToRightAlphas:Array = new Array(); var leftToRightRatios:Array = new Array(); var leftToRightPartition:Number = 255 / (leftToRightColors.length - 1); var pixelColor:Number; var i:int; //Push arrays for (i = 0; i < leftToRightColors.length; i++) { leftToRightAlphas.push(1); leftToRightRatios.push(i * leftToRightPartition); } //Graphics matrix and lineStyle var leftToRightColorsMatrix:Matrix = new Matrix(); leftToRightColorsMatrix.createGradientBox(gradientRectWidth, 1); graphics.lineStyle(1, 0, 1, false, LineScaleMode.NONE, CapsStyle.NONE); for (i = 0; i < gradientRectWidth; i++) { graphics.lineGradientStyle(GradientType.LINEAR, leftToRightColors, leftToRightAlphas, leftToRightRatios, leftToRightColorsMatrix); graphics.moveTo(i, 0); graphics.lineTo(i, gradientRectHeight); } } } } how can i solve this problem?

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  • Collision point of 2 curves in a 3d-room

    - by Frank
    Hello, i am programming a small game for quite some time. We started coding a small FPS-Shooter inside of a project at school to get a bit experience using directX. I dont know why, but i couldnt stop the project and started programming at home aswell. At the moment i am trying to create some small AI. Of cause thats definatlly not easy, but thats my personal goal anyways. The topic could prolly fill multiple books hehe. I've got the walking part of my bots done so far. They walk along a scriped path. I am not working on the "aiming" of the bots. While programming that i hit on some math problem i couldnt solve yet. I hope of your input on this to help me get further. Concepts, ideas and everything else are highly appreciated. Problem: Calculate the position (D3DXVECTOR3) where the curve of the projectile (depends on gravity, speed), hit the curved of the enemys walking path (depends on speed). We assume that the enemy walks in a constant line. Known variables: float projectilSpeed = 2000 m/s //speed of the projectile per second float gravitation = 9.81 m/s^2 //of cause the gravity lol D3DXVECTOR3 targetPosition //position of the target stored in a vector (x,y,z) D3DXVECTOR3 projectilePosition //position of the projectile D3DXVECTOR3 targetSpeed //stores the change of the targets position in the last second Variabledefinition ProjectilePosition at time of collision = ProjectilePos_t TargetPosition at time of collision = TargetPos_t ProjectilePosition at time 0, now = ProjectilePos_0 TargetPosition at time 0, now = TargetPos_0 Time to impact = t Aim-angle = theta My try: Found a formular to calculate "drop" (Drop of the projectile based on the gravity) on Wikipedia: float drop = 0.5f * gravity * t * t The speed of the projectile has a horizontal and a vertical part.. Found a formular for that on wikipedia aswell: ProjectilVelocity.x = projectilSpeed * cos(theta) ProjectilVelocity.y = projectilSpeed * sin(theta) So i would assume this is true for the projectile curve: ProjectilePos_t.x = ProjectilePos_0.x + ProjectileSpeed * t ProjectilePos_t.y = ProjectilePos_0.y + ProjectileSpeed * t + 0.5f * gravity * t * t ProjectilePos_t.z = ProjectilePos_0.z + ProjectileSpeed * t The target walk with a constant speed, so we can determine his curve by this: TargetPos_t = TargetPos_0 + TargetSpeed * D3DXVECTOR3(t, t, t) Now i dont know how to continue. I have to solve it somehow to get a hold on the time to impact somehow. As a basic formular i could use: float time = distanz / projectileSpeed But that wouldnt be truly correct as it would assume a linear "Trajectory". We just find this behaivor when using a rocket. I hope i was able to explain the problem as much as possible. If there are questions left, feel free to ask me! Greets from germany, Frank

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  • Fast pixelshader 2D raytracing

    - by heishe
    I'd like to do a simple 2D shadow calculation algorithm by rendering my environment into a texture, and then use raytracing to determine what pixels of the texture are not visible to the point light (simply handed to the shader as a vec2 position) . A simple brute force algorithm per pixel would looks like this: line_segment = line segment between current pixel of texture and light source For each pixel in the texture: { if pixel is not just empty space && pixel is on line_segment output = black else output = normal color of the pixel } This is, of course, probably not the fastest way to do it. Question is: What are faster ways to do it or what are some optimizations that can be applied to this technique?

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  • Preallocating memory with C++ in realtime environment

    - by Elazar Leibovich
    I'm having a function which gets an input buffer of n bytes, and needs an auxillary buffer of n bytes in order to process the given input buffer. (I know vector is allocating memory at runtime, let's say that I'm using a vector which uses static preallocated memory. Imagine this is NOT an STL vector.) The usual approach is void processData(vector<T> &vec) { vector<T> &aux = new vector<T>(vec.size()); //dynamically allocate memory // process data } //usage: processData(v) Since I'm working in a real time environment, I wish to preallocate all the memory I'll ever need in advance. The buffer is allocated only once at startup. I want that whenever I'm allocating a vector, I'll automatically allocate auxillary buffer for my processData function. I can do something similar with a template function static void _processData(vector<T> &vec,vector<T> &aux) { // process data } template<size_t sz> void processData(vector<T> &vec) { static aux_buffer[sz]; vector aux(vec.size(),aux_buffer); // use aux_buffer for the vector _processData(vec,aux); } // usage: processData<V_MAX_SIZE>(v); However working alot with templates is not much fun (now let's recompile everything since I changed a comment!), and it forces me to do some bookkeeping whenever I use this function. Are there any nicer designs around this problem?

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  • Breaking out of first element in IHTMLTxtRange

    - by XwipeoutX
    I'm trying to do a rich text editor for a web application, and I need to be able to mark some elements in the text as uneditable by the user. The reason for this is they're placeholders for dynamic content (like created date) that I want to have a live preview for. Take the following Code as an example - there's no toolbar or anything in this one, for light weightness, but the textarea and html are synchronized. <!-- DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" --> <html> <head> <title>Hi</title> <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.min.js"></script> <script> $(function() { g = {}; g.iFrame = document.createElement("IFRAME"); $("#frameContainer").append(g.iFrame); g.iDoc = g.iFrame.contentWindow.document; g.iDoc.designMode = "on"; g.jTextArea = $("#textContainer textarea"); setTimeout(function() { g.iDoc.body.innerHTML = "<b class=\"notype\">Cannot type here</b>"; $(g.iDoc).trigger("keyup"); $(g.iDoc.body).focus(); }, 0); $(g.iDoc).keyup(function() { g.jTextArea.text(g.iDoc.body.innerHTML); }); g.jTextArea.keyup(function() { g.iDoc.body.innerHTML = this.innerText; }); var getSelection = function() { if (typeof g.iDoc.selection !== "undefined" && g.iDoc.selection.type !== "Text" && g.iDoc.selection.type !== "None") { g.iDoc.selection.clear(); } return g.iDoc.selection.createRange(); }; $(g.iDoc).keypress(function(event) { // If we're in a marked field, disable the operation. var sel = getSelection(); if ($(sel.parentElement()).hasClass('notype')) { sel.moveToElementText(sel.parentElement()); sel.collapse(); sel.move("character", -1); sel.select(); $("#log").append("<div>outside of thing</div>"); } }); $(testLink).click(function() { // Try and insert stuff at the front $(g.iDoc.body).focus(); var sel = getSelection(); sel.moveToElementText(sel.parentElement()); sel.collapse(); sel.move("character", -100); sel.pasteHTML("Before html?"); $(g.iDoc).trigger("keyup"); $(g.iDoc.body).focus(); }); }); </script> </head> <body id="#body"> <div id="container"> <div id="frameContainer"> <h1> Frame</h1> </div> <div id="textContainer"> <h1> Text</h1> <textarea rows="10" cols="80"></textarea> </div> <a href="#" id="testLink">Test</a> <div id="log"> </div> </div> </body> </html> In the keyup binding, I can successfuly detect if I'm inside another element, and move the cursor to the front of the text before inserting it no problem. However, since there is no text before the element marked as 'notype', it gets inserted inside the same element. This is double bad when the user presses "enter", as a new tag is genrated, and the "notype" tag is duplicated, obviously not required. I want the behaviour as follows: * If the user types while the cursor is in the 'notype' tag, the cursor is moved to front and the text goes there * If the cursor is at the last position inside the 'notype' tag, then the text appears after the tag * If the user types anywhere else, it's inserted as always. The link at the bottom tries to manually put the cursor at the front and insert the html. Obviously fails. I know this one can work by doing something like $(g.iDoc.body).prepend("before!"), but this obviously won't work in a real scenario (using keyup).

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  • Is a text file with names/pixel locations something a graphic artist can/should produce? [on hold]

    - by edA-qa mort-ora-y
    I have an artist working on 2D graphics for a game UI. He has no problem producing a screenshot showing all the bits, but we're having some trouble exporting this all into an easy-to-use format. For example, take the game HUD, which is a bunch of elements laid out around the screen. He exports the individual graphics for each one, but how should he communicate the positioning of each of them? My desire is to have a yaml file (or some other simple markup file) that contains the name of each asset and pixel position of that element. For example: fire_icon: pos: 20, 30 fire_bar: pos: 30, 80 Is producing such files a common task of a graphic artist? Is is reasonable to request them to produce such files as part of their graphic work?

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  • How to render a retro-like pixel graphics from 3d models?

    - by momijigari
    I was wondering if there's a possibility to render a retro-pixel-like graphics from 3d model in real time? I'm talking about the Starfarer-like graphics. I know it's hand drawn, and it's 2d. But if I need a 3d objects with the same aesthetics? I'm currently working with Flash. But I don't need any ready-solutions, I just want to understand the principle from any other platform if there is one. So if anybody met anything like this I would appreciate your help. (If it's not possible to do in real time, I could at least pre-render a sequence of sprites. It would be much better than creating hundreds of hand-drawn ones)

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  • How can i get almost pixel perfect collision detection in a multiplayer game?

    - by Freddy
    I'm currently working on a multiplayer game for iPhone. The problem i have, as with all multiplayer games, is that the other user will always see everything at a non-constant delay. The game I'm making need to have a almost pixel perfect collision detection, but 1 or 2 pixels off is not that big of a deal. How can I possibly get this working? I guess I could just set local player to also be at X ms delay. However this will probably just be worse and feel sloppy when the user input. I know this problem is probably something network programmers deal with everyday and I would be glad if someone could give me a possible solution for this.

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  • Vector-based fonts vs. bitmap fonts in (2d) games?

    - by jmp97
    I know that many games are using bitmap fonts. Which are the advantages for vector-based font rendering / manipulation when compared to bitmap fonts and in which scenarios would they matter the most? Prefer a focus on 2d games when answering this question. If relevant, please include examples for games using either approach. Some factors you might consider: amount of text used in the game scaling of text overlaying glyphs and anti-aliasing general rendering quality font colors and styling user interface requirements localisation / unicode text wrapping and formatting cross-platform deployment 2d vs 3d Background: I am developing a simple falling blocks game in 2d, targeted for pc. I would like to add text labels for level, score, and menu buttons. I am using SFML which uses FreeType internally, so vector-based features are easily available for my project. In my view, font sizes in simple games often don't vary, and bitmap fonts should be easier for cross-platform concerns (font-formats and font rendering quality). But I am unsure if I am missing some important points here, especially since I want to polish the looks of the final game.

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  • What are the advantages to use vector-based fonts over bitmap fonts in (2d) games?

    - by jmp97
    I know that many games are using bitmap fonts. Which are the advantages for vector-based font rendering / manipulation when compared to bitmap fonts and in which scenarios would they matter the most? Prefer a focus on 2d games when answering this question. If relevant, please include examples for games using either approach. Some factors you might consider: amount of text used in the game scaling of text overlaying glyphs and anti-aliasing general rendering quality font colors and styling user interface requirements localisation / unicode text wrapping and formatting cross-platform deployment 2d vs 3d Background: I am developing a simple falling blocks game in 2d, targeted for pc. I would like to add text labels for level, score, and menu buttons. I am using SFML which uses FreeType internally, so vector-based features are easily available for my project. In my view, font sizes in simple games often don't vary, and bitmap fonts should be easier for cross-platform concerns (font-formats and font rendering quality). But I am unsure if I am missing some important points here, especially since I want to polish the looks of the final game.

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  • Problems with SAT Collision Detection

    - by DJ AzKai
    I'm doing a project in one of my modules for college in C++ with SFML and I was hoping someone may be able to help me. I'm using a vector of squares and triangles and I am using the SAT collision detection method to see if objects collide and to make the objects respond to the collision appropriately using the MTV(minimum translation vector) Below is my code: //from the main method int main(){ // Create the main window sf::RenderWindow App(sf::VideoMode(800, 600, 32), "SFML OpenGL"); // Create a clock for measuring time elapsed sf::Clock Clock; srand(time(0)); //prepare OpenGL surface for HSR glClearDepth(1.f); glClearColor(0.3f, 0.3f, 0.3f, 0.f); //background colour glEnable(GL_DEPTH_TEST); glDepthMask(GL_TRUE); //// Setup a perspective projection & Camera position glMatrixMode(GL_PROJECTION); glLoadIdentity(); //set up a 3D Perspective View volume //gluPerspective(90.f, 1.f, 1.f, 300.0f);//fov, aspect, zNear, zFar //set up a orthographic projection same size as window //this mease the vertex coordinates are in pixel space glOrtho(0,800,0,600,0,1); // use pixel coordinates // Finally, display rendered frame on screen vector<BouncingThing*> triangles; for(int i = 0; i < 10; i++) { //instantiate each triangle; triangles.push_back(new BouncingTriangle(Vector2f(rand() % 700, rand() % 500), 3)); } vector<BouncingThing*> boxes; for(int i = 0; i < 10; i++) { //instantiate each box; boxes.push_back(new BouncingBox(Vector2f(rand() % 700, rand() % 500), 4)); } CollisionDetection * b = new CollisionDetection(); // Start game loop while (App.isOpen()) { // Process events sf::Event Event; while (App.pollEvent(Event)) { // Close window : exit if (Event.type == sf::Event::Closed) App.close(); // Escape key : exit if ((Event.type == sf::Event::KeyPressed) && (Event.key.code == sf::Keyboard::Escape)) App.close(); } //Prepare for drawing // Clear color and depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Apply some transformations glMatrixMode(GL_MODELVIEW); glLoadIdentity(); for(int i = 0; i < 10; i++) { triangles[i]->draw(); boxes[i]->draw(); triangles[i]->update(Vector2f(800,600)); boxes[i]->draw(); boxes[i]->update(Vector2f(800,600)); } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(boxes[i]))); } } for(int j = 0; j < 10; j++) { for(int i = 0; i < 10; i++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { triangles[j]->setCollision(b->CheckCollision(*(triangles[j]),*(triangles[i]))); } } for(int i = 0; i < triangles.size(); i++) { for(int j = i + 1; j < triangles.size(); j ++) { boxes[j]->setCollision(b->CheckCollision(*(boxes[j]),*(boxes[i]))); } } App.display(); } return EXIT_SUCCESS; } (ignore this line) //from the BouncingThing.cpp BouncingThing::BouncingThing(Vector2f position, int noSides) : pos(position), pi(3.14), radius(3.14), nSides(noSides) { collided = false; if(nSides ==3) { Vector2f vert1 = Vector2f(-12.0f,-12.0f); Vector2f vert2 = Vector2f(0.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); } else if(nSides == 4) { Vector2f vert1 = Vector2f(-12.0f,12.0f); Vector2f vert2 = Vector2f(12.0f, 12.0f); Vector2f vert3 = Vector2f(12.0f,-12.0f); Vector2f vert4 = Vector2f(-12.0f, -12.0f); verts.push_back(vert1); verts.push_back(vert2); verts.push_back(vert3); verts.push_back(vert4); } velocity.x = ((rand() % 5 + 1) / 3) + 1; velocity.y = ((rand() % 5 + 1) / 3 ) +1; } void BouncingThing::update(Vector2f screenSize) { Transform t; t.rotate(0); for(int i=0;i< verts.size(); i++) { verts[i]=t.transformPoint(verts[i]); } if(pos.x >= screenSize.x || pos.x <= 0) { velocity.x *= -1; } if(pos.y >= screenSize.y || pos.y <= 0) { velocity.y *= -1; } if(collided) { //velocity.x *= -1; //velocity.y *= -1; collided = false; } pos += velocity; } void BouncingThing::setCollision(bool x){ collided = x; } void BouncingThing::draw() { glBegin(GL_POLYGON); glColor3f(0,1,0); for(int i = 0; i < verts.size(); i++) { glVertex2f(pos.x + verts[i].x,pos.y + verts[i].y); } glEnd(); } vector<Vector2f> BouncingThing::getNormals() { vector<Vector2f> normalVerts; if(nSides == 3) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); Vector2f ac = Vector2f((verts[2].x + pos.x) - (verts[0].x + pos.x), (verts[2].y + pos.y) - (verts[0].y + pos.y)); ac = flip(ac); ac.x *= -1; normalVerts.push_back(ac); return normalVerts; } if(nSides ==4) { Vector2f ab = Vector2f((verts[1].x + pos.x) - (verts[0].x + pos.x), (verts[1].y + pos.y) - (verts[0].y + pos.y)); ab = flip(ab); ab.x *= -1; normalVerts.push_back(ab); Vector2f bc = Vector2f((verts[2].x + pos.x) - (verts[1].x + pos.x), (verts[2].y + pos.y) - (verts[1].y + pos.y)); bc = flip(bc); bc.x *= -1; normalVerts.push_back(bc); return normalVerts; } } Vector2f BouncingThing::flip(Vector2f v){ float vyTemp = v.x; float vxTemp = v.y * -1; return Vector2f(vxTemp, vyTemp); } (Ignore this line) CollisionDetection::CollisionDetection() { } vector<float> CollisionDetection::bubbleSort(vector<float> w) { int temp; bool finished = false; while (!finished) { finished = true; for (int i = 0; i < w.size()-1; i++) { if (w[i] > w[i+1]) { temp = w[i]; w[i] = w[i+1]; w[i+1] = temp; finished=false; } } } return w; } class Vector{ public: //static int dp_count; static float dot(sf::Vector2f a,sf::Vector2f b){ //dp_count++; return a.x*b.x+a.y*b.y; } static float length(sf::Vector2f a){ return sqrt(a.x*a.x+a.y*a.y); } static Vector2f add(Vector2f a, Vector2f b) { return Vector2f(a.x + b.y, a.y + b.y); } static sf::Vector2f getNormal(sf::Vector2f a,sf::Vector2f b){ sf::Vector2f n; n=a-b; n/=Vector::length(n);//normalise float x=n.x; n.x=n.y; n.y=-x; return n; } }; bool CollisionDetection::CheckCollision(BouncingThing & x, BouncingThing & y) { vector<Vector2f> xVerts = x.getVerts(); vector<Vector2f> yVerts = y.getVerts(); vector<Vector2f> xNormals = x.getNormals(); vector<Vector2f> yNormals = y.getNormals(); int size; vector<float> xRange; vector<float> yRange; for(int j = 0; j < xNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(xNormals[j], Vector2f(xVerts[i].x, xVerts[i].x))); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(xNormals[j], Vector2f(yVerts[i].x , yVerts[i].y))); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } float x3 = Min(xRange[0], yRange[0]); float y3 = Max(xRange[xRange.size() - 1], yRange[yRange.size() - 1]); float length = Max(x3, y3) - Min(x3, y3); } for(int j = 0; j < yNormals.size(); j++) { Vector p; for(int i = 0; i < xVerts.size(); i++) { xRange.push_back(p.dot(yNormals[j], xVerts[i])); } for(int i = 0; i < yVerts.size(); i++) { yRange.push_back(p.dot(yNormals[j], yVerts[i])); } yRange = bubbleSort(yRange); xRange = bubbleSort(xRange); if(xRange[xRange.size() - 1] < yRange[0] || yRange[yRange.size() - 1] < xRange[0]) { return false; } } return true; } float CollisionDetection::Min(float min, float max) { if(max < min) { min = max; } else return min; } float CollisionDetection::Max(float min, float max) { if(min > max) { max = min; } else return min; } On the screen the objects will freeze for a small amount of time before moving off again. However the problem is is that when this happens there are no collisions actually happening and I would really love to find out where the flaw is in the code. If you need any more information/code please don't hesitate to ask and I'll reply as soon as possible Regards, AzKai

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • Optimizing collision engine bottleneck

    - by Vittorio Romeo
    Foreword: I'm aware that optimizing this bottleneck is not a necessity - the engine is already very fast. I, however, for fun and educational purposes, would love to find a way to make the engine even faster. I'm creating a general-purpose C++ 2D collision detection/response engine, with an emphasis on flexibility and speed. Here's a very basic diagram of its architecture: Basically, the main class is World, which owns (manages memory) of a ResolverBase*, a SpatialBase* and a vector<Body*>. SpatialBase is a pure virtual class which deals with broad-phase collision detection. ResolverBase is a pure virtual class which deals with collision resolution. The bodies communicate to the World::SpatialBase* with SpatialInfo objects, owned by the bodies themselves. There currenly is one spatial class: Grid : SpatialBase, which is a basic fixed 2D grid. It has it's own info class, GridInfo : SpatialInfo. Here's how its architecture looks: The Grid class owns a 2D array of Cell*. The Cell class contains two collection of (not owned) Body*: a vector<Body*> which contains all the bodies that are in the cell, and a map<int, vector<Body*>> which contains all the bodies that are in the cell, divided in groups. Bodies, in fact, have a groupId int that is used for collision groups. GridInfo objects also contain non-owning pointers to the cells the body is in. As I previously said, the engine is based on groups. Body::getGroups() returns a vector<int> of all the groups the body is part of. Body::getGroupsToCheck() returns a vector<int> of all the groups the body has to check collision against. Bodies can occupy more than a single cell. GridInfo always stores non-owning pointers to the occupied cells. After the bodies move, collision detection happens. We assume that all bodies are axis-aligned bounding boxes. How broad-phase collision detection works: Part 1: spatial info update For each Body body: Top-leftmost occupied cell and bottom-rightmost occupied cells are calculated. If they differ from the previous cells, body.gridInfo.cells is cleared, and filled with all the cells the body occupies (2D for loop from the top-leftmost cell to the bottom-rightmost cell). body is now guaranteed to know what cells it occupies. For a performance boost, it stores a pointer to every map<int, vector<Body*>> of every cell it occupies where the int is a group of body->getGroupsToCheck(). These pointers get stored in gridInfo->queries, which is simply a vector<map<int, vector<Body*>>*>. body is now guaranteed to have a pointer to every vector<Body*> of bodies of groups it needs to check collision against. These pointers are stored in gridInfo->queries. Part 2: actual collision checks For each Body body: body clears and fills a vector<Body*> bodiesToCheck, which contains all the bodies it needs to check against. Duplicates are avoided (bodies can belong to more than one group) by checking if bodiesToCheck already contains the body we're trying to add. const vector<Body*>& GridInfo::getBodiesToCheck() { bodiesToCheck.clear(); for(const auto& q : queries) for(const auto& b : *q) if(!contains(bodiesToCheck, b)) bodiesToCheck.push_back(b); return bodiesToCheck; } The GridInfo::getBodiesToCheck() method IS THE BOTTLENECK. The bodiesToCheck vector must be filled for every body update because bodies could have moved meanwhile. It also needs to prevent duplicate collision checks. The contains function simply checks if the vector already contains a body with std::find. Collision is checked and resolved for every body in bodiesToCheck. That's it. So, I've been trying to optimize this broad-phase collision detection for quite a while now. Every time I try something else than the current architecture/setup, something doesn't go as planned or I make assumption about the simulation that later are proven to be false. My question is: how can I optimize the broad-phase of my collision engine maintaining the grouped bodies approach? Is there some kind of magic C++ optimization that can be applied here? Can the architecture be redesigned in order to allow for more performance? Actual implementation: SSVSCollsion Body.h, Body.cpp World.h, World.cpp Grid.h, Grid.cpp Cell.h, Cell.cpp GridInfo.h, GridInfo.cpp

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  • How do I simplify a 2D game grid for level management while keeping its by-pixel features?

    - by Eric Thoma
    (I cross-posted this from StackOverflow as this seems to be a more appropriate forum. I've looked around a little here and I did not find an answer, so I hope this is not a recurring question.) This is a question dealing with 2D world design. I am playing around by creating a 2D bird's eye view shooter game, and I am looking to make the game sleek and advanced. I hope to be able to write physics so projectiles have momentum and knock-down properties. I am immediately running into the problem of world design. I need a way to have level files that store everything there is about a game. This is easiest by just having a grid of objects. But there are thin-walls and other objects that don't seem to fit into a traditional cell of a grid. I want to be able to fit all these together so I can streamline level design; so I don't have to put in the exact pixel-specific start and end of a wall. There doesn't seem to be an obvious translation from level file to game without forcing myself into a pacman-life scenario, meaning a scenario where the game feels boxy and discrete. There is a contrast between the smoothly (relatively) moving characters and finite jumps in a grid. I would appreciate an answer that would describe implementation options or point me to resources that do. I would also appreciate references to sites that teach game design. The language I am using is Java (although I would love to use C or C++, but I can never find convenient resources in those languages). Thank you for any answers. Please leave any questions in the space below; I will be able to answer them later tonight (28th Nov).

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  • How does this snippet of code create a ray direction vector?

    - by Isaac Waller
    In the Minecraft source code, this code is used to create a direction vector for a ray from pitch and yaw:' float f1 = MathHelper.cos(-rotationYaw * 0.01745329F - 3.141593F); float f3 = MathHelper.sin(-rotationYaw * 0.01745329F - 3.141593F); float f5 = -MathHelper.cos(-rotationPitch * 0.01745329F); float f7 = MathHelper.sin(-rotationPitch * 0.01745329F); return Vec3D.createVector(f3 * f5, f7, f1 * f5); I was wondering how it worked, and what is the constant 0.01745329F?

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  • How do I use the gravity vector to correctly transform scene for augmented reality?

    - by gpdawson
    I'm trying figure out how to get an OpenGL specified object to be displayed correctly according to the device orientation (ie. according to the gravity vector from the accelerometer, and heading from compass). The GLGravity sample project has an example which is almost like this (despite ignoring heading), but it has some glitches. For example, the teapot jumps 180deg as the device viewing angle crosses the horizon, and it also rotates spuriously if you tilt the device from portrait into landscape. This is fine for the context of this app, as it just shows off an object and it doesn't matter that it does these things. But it means that the code just doesn't work when you attempt to emulate real life viewing of an OpenGL object according to the device's orientation. What happens is that it almost works, but the heading rotation you apply from the compass gets "corrupted" by the spurious additional rotations seen in the GLGravity example project. Can anyone provide sample code that shows how to adjust correctly for the device orientation (ie. gravity vector), or to fix the GLGravity example so that it doesn't include spurious heading changes? //Clear matrix to be used to rotate from the current referential to one based on the gravity vector bzero(matrix, sizeof(matrix)); matrix[3][3] = 1.0; //Setup first matrix column as gravity vector matrix[0][0] = accel[0] / length; matrix[0][1] = accel[1] / length; matrix[0][2] = accel[2] / length; //Setup second matrix column as an arbitrary vector in the plane perpendicular to the gravity vector {Gx, Gy, Gz} defined by by the equation "Gx * x + Gy * y + Gz * z = 0" in which we arbitrarily set x=0 and y=1 matrix[1][0] = 0.0; matrix[1][1] = 1.0; matrix[1][2] = -accel[1] / accel[2]; length = sqrtf(matrix[1][0] * matrix[1][0] + matrix[1][1] * matrix[1][1] + matrix[1][2] * matrix[1][2]); matrix[1][0] /= length; matrix[1][1] /= length; matrix[1][2] /= length; //Setup third matrix column as the cross product of the first two matrix[2][0] = matrix[0][1] * matrix[1][2] - matrix[0][2] * matrix[1][1]; matrix[2][1] = matrix[1][0] * matrix[0][2] - matrix[1][2] * matrix[0][0]; matrix[2][2] = matrix[0][0] * matrix[1][1] - matrix[0][1] * matrix[1][0]; //Finally load matrix glMultMatrixf((GLfloat*)matrix);

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