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  • Index Check and Correct Character Display in a Console Hangman Game for Java

    - by Jen
    I have this problem wherein, I can not display the correct characters given by the character. Here's what I meant: String words, in; String replaced_words; Scanner s = new Scanner (System.in); System.out.println("Enter a line of words basing on an event, verse, place or a name of a person."); words = s.nextLine(); System.out.println("The words you just placed are now accepted."); //using char array method, we tried to place the words into a characters array. char [] c = words.toCharArray(); // we need to replace the replaced_words = words.replace(' ', '_').replaceAll("[^\\-]", "-"); for (int i = 0; i < replaced_words.length(); i++) { System.out.print(replaced_words.charAt(i) + " "); } System.out.println("Now, please input a character, guessing the words you just placed."); in = s.nextLine(); in that code, want that the user, when types a word (or should it be character?), any of the correct character the user inputs will be displayed, and changes the hyphen to it...(more like the hangman series of games). How can I achieve this?

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  • Is it considered poor programming to do this with xna components?

    - by Rob
    I created my own Menu System that is event driven. In order to have a loading screen and multithreaded loading to work, I devised this sort of implementation: //Let's check if the game is done loading. if (_game != null) { _gameLoaded = _game.DoneLoading; } //This means the game is loading still, //therefore the loading screen should be active. if (!_gameLoaded && _gameActive) { _gameScreenList[2].UpdateMenu(); } //The loading screen was selected. if (_gameScreenList[2].CurrentState == GameScreen.State.Shown && !_gameActive) { Components.Add(_game = new ParadoxGame(this)); _game.Initialize(); //Initializes the Game so that the loading can begin. _gameActive = true; } In the XNA Game Component that contains the actual game, in the LoadContent method I simply created a new Thread that calls another method ThreadLoad that has all the actual loading. I also have a boolean variable called DoneLoading in the XNA Game Component that is set to true at the end of the ThreadLoad. I am wondering if this is a poor implementation.

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  • How to handle key in PhP array if the key contains japanese characters [migrated]

    - by Jim Thio
    I have this array: [ID] => ????????-???????????__35.79_139.72 [Email] => [InBuildingAddress] => [Price] => [Street] => [Title] => ???????? ??????????? [Website] => [Zip] => [Rating Star] => 0 [Rating Weight] => 0 [Latitude] => 35.7865334803033 [Longitude] => 139.716800710514 [Building] => [City] => Unknown_Japan [OpeningHour] => [TimeStamp] => 0000-00-00 00:00:00 [CountViews] => 0 Then I do something like this: $output[$info['ID']]=$info; //mess up here $tes=$info['ID']['Title']; Well guess what it messes up. Basically even though the content of an array in PhP can be Japanese. Is this true? What's wrong. The error I got is: Debug Warning: /sdfdsfdf/api/test2.php line 36 - Cannot find element ????????-???????????__35.79_139.72 in variable Debug Warning: /sdfdsfdf/api/test2.php line 36 - main() [function.main]: It is not safe to rely on the system's timezone settings. You are required to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Krasnoyarsk' for '7.0/no DST' instead So many question mark Why is this happening. What's really going on inside PhP? Where can I learn more of such things. Most importantly, what would be the best way to handle this situation. Should I tell PhP to internally always use UTF-8? Does PhP array inherenty cannot use non ascii id?

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  • canvas tile grid, hover effects, single tilesheet, etc

    - by user121730
    I'm currently in the process of building both the client and server side of an html5, canvas, and WebSocket game. This is what I have thus far for the client: http://jsfiddle.net/dDmTf/7/ Current obstacles The hover effect has no idea what to put back after the mouse leaves. Currently it's just drawing a "void" tile, but I can't figure out how to redraw a single tile without redrawing the whole map. How would I go about storing multiple layers within the map variable? I was considering just using a multi-dimensional array for each layer (similar to what you see as the current array), and just iterating through it, but is that really an efficient way of doing it? Side note The tile sheet being used for the jsfiddle display is only for development. I'll be replacing it as things progress in the engine. I hope you can help! Hopefully you guys can help me, I've been struggling to get through things, since I'm learning how things kind of stuff works as I go. If you guys have any pointers for my JavaScript, feel free. As I'm more or less learning advanced usage as I go, I'm sure I'm doing plenty of things wrong. Note: I will continue to update this post as the engine improves, but updating the jsfiddle link and updating the obstacles list by striking things that have been solved, or adding additions. Thanks!

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  • Calculate travel time on road map with semaphores

    - by Ivansek
    I have a road map with intersections. At intersections there are semaphores. For each semaphore I generate a red light time and green light time which are represented with syntax [R:T1, G:T2], for example: 119 185 250 A ------- B: [R:6, G:4] ------ C: [R:5, G:5] ------ D I want to calculate a car travel time from A - D. Now I do this with this pseudo code: function get_travel_time(semaphores_configuration) { time = 0; for( i=1; i<path.length;i++) { prev_node = path[i-1]; next_node = path[i]); cost = cost_between(prev_node, next_node) time += (cost/movement_speed) // movement_speed = 50px per second light_times = get_light_times(path[i], semaphore_configurations) lights_cycle = get_lights_cycle(light_times) // Eg: [R,R,R,G,G,G,G], where [R:3, G:4] lights_sum = light_times.green_time+light_times.red_light; // Lights cycle time light = lights_cycle[cost%lights_sum]; if( light == "R" ) { time += light_times.red_light; } } return time; } So for distance 119 between A and B travel time is, 119/50 = 2.38s ( exactly mesaured time is between 2.5s and 2.6s), then we add time if we came at a red light when at B. If we came at a red light is calculated with lines: lights_cycle = get_lights_cycle(light_times) // Eg: [R,R,R,G,G,G,G], where [R:3, G:4] lights_sum = light_times.green_time+light_times.red_light light = lights_cycle[cost%lights_sum]; if( light == "R" ) { time += light_times.red_light; } This pseudo code doesn't calculate exactly the same times as they are mesaured, but the calculations are very close to them. Any idea how I would calculate this?

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  • Oracle R Distribution 2-13.2 Update Available

    - by Sherry LaMonica
    Oracle has released an update to the Oracle R Distribution, an Oracle-supported distribution of open source R. Oracle R Distribution 2-13.2 now contains the ability to dynamically link the following libraries on both Windows and Linux: The Intel Math Kernel Library (MKL) on Intel chips The AMD Core Math Library (ACML) on AMD chips To take advantage of the performance enhancements provided by Intel MKL or AMD ACML in Oracle R Distribution, simply add the MKL or ACML shared library directory to the LD_LIBRARY_PATH system environment variable. This automatically enables MKL or ACML to make use of all available processors, vastly speeding up linear algebra computations and eliminating the need to recompile R.  Even on a single core, the optimized algorithms in the Intel MKL libraries are faster than using R's standard BLAS library. Open-source R is linked to NetLib's BLAS libraries, but they are not multi-threaded and only use one core. While R's internal BLAS are efficient for most computations, it's possible to recompile R to link to a different, multi-threaded BLAS library to improve performance on eligible calculations. Compiling and linking to R yourself can be involved, but for many, the significantly improved calculation speed justifies the effort. Oracle R Distribution notably simplifies the process of using external math libraries by enabling R to auto-load MKL or ACML. For R commands that don't link to BLAS code, taking advantage of database parallelism using embedded R execution in Oracle R Enterprise is the route to improved performance. For more information about rebuilding R with different BLAS libraries, see the linear algebra section in the R Installation and Administration manual. As always, the Oracle R Distribution is available as a free download to anyone. Questions and comments are welcome on the Oracle R Forum.

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  • Turn Based Event Algorithm

    - by GamersIncoming
    I'm currently working on a small roguelike in XNA, which sees the player in a randomly generated series of dungeons fending off creeps, as you might expect. As with most roguelikes, the player makes a move, and then each of the creeps currently active on screen will make a move in turns, until all creeps have updated, and it return's to the player's go. On paper, the simple algorithm is straightforward: Player takes turn Turn Number increments For each active creep, update Position Once all active creeps have updated, allow player to take next turn However, when it comes to actually writing this in more detail, the concept becomes a bit more tricky for me. So my question comes as this: what is the best way to handle events taking turns to trigger, where the completion of each last event triggers the next, when dealing with a large number of creeps (probably stored as an array of an enemy object), and is there an easier way to create some kind of engine that just takes all objects that need updating and chains them together so their updates follow suit? I'm not asking for code, just algorithms and theory in the direction of objects triggering updates one after the other, in a turn based manner. Thanks in advance. Edited: Here's the code I currently have that is horrible :/ if (player.getTurnOver() && updateWait == 0) { if (creep[creepToUpdate].getActive()) { creep[creepToUpdate].moveObject(player, map1); updateWait = 10; } if (creepToUpdate < creep.Length -1) { creepToUpdate++; } else { creepToUpdate = 0; player.setTurnOver(false); } } if (updateWait > 0) { updateWait--; }

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  • Disappearring instances of VertexPositionColor using MonoGame

    - by Rosko
    I am a complete beginner in graphics developing with XNA/Monogame. Started my own project using Monogame 3.0 for WinRT. I have this unexplainable issue that some of the vertices disappear while doing some updates on them. Basically, it is a game with balls who collide with the walls and with each other and in certain conditions they explode. When they explode they disappear. Here is a video demonstrating the issue. I used wireframes so that it is easier to see how vertices are missing. The perfect exploding balls are the ones which are result by user input with mouse clicking. Thanks for the help. The situations is: I draw user primitives with triangle strips using like this graphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip, circleVertices, 0, primitiveCount); All of the primitives are in the z-plane (z = 0), I thought that it is the culling in action. I tried setting the culling mode to none but it did not help. Here is the code responsible for the explosion private void Explode(GameTime gameTime, ref List<Circle> circles) { if (this.isExploding) { for (int i = 0; i < this.circleVertices.Length; i++) { if (this.circleVertices[i] != this.circleCenter) { if (Vector3.Distance(this.circleVertices[i].Position, this.circleCenter.Position) < this.explosionRadius * precisionCoefficient) { var explosionVector = this.circleVertices[i].Position - this.circleCenter.Position; explosionVector.Normalize(); explosionVector *= explosionSpeed; circleVertices[i].Position += explosionVector * (float)gameTime.ElapsedGameTime.TotalSeconds; } else { circles.Remove(this); } } } } } I'd be really greatful if anyone has suggestions about how to fix this issue.

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  • How to manage Areas/Levels in an RPG?

    - by Hexlan
    I'm working on an RPG and I'm trying to figure out how to manage the different levels/areas in the game. Currently I create a new state (source file) for every area, defining its unique aspects. My concern is that as the game grows the number of class files will become unmanageable with all the towns, houses, shops, dungeons, etc. that I need to keep track of. I would also prefer to separate my levels from the source code because non-programmer members of the team will be creating levels, and I would like the engine to be as free from game specific code as possible. I'm thinking of creating a class that provides all the functions that will be the same between all the levels/areas with a unique member variable that can be used to look up level specifics from data. This way I only need to define level/area once in the code, but can create multiple instances each with its own unique aspects provided by data. Is this a good way to go about solving the issue? Is there a better way to handle a growing number of levels?

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  • Sampling Heightmap Edges for Normal map

    - by pl12
    I use a Sobel filter to generate normal maps from procedural height maps. The heightmaps are 258x258 pixels. I scale my texture coordinates like so: texCoord = (texCoord * (256/258)) + (1/258) Yet even with this I am left with the following problem: As you can see the edges of the normal map still proves to be problematic. Putting the texture wrap mode to "clamp" also proved no help. EDIT: The Sobel Filter function by sampling the 8 surrounding pixels around a given pixel so that a derivative can be calculated in order to find the "normal" of the given pixel. The texture coordinates are instanced once per quad (for the quadtree that makes up the world) and are created as follows (it is quite possible that the problem results from the way I scale and offset the texCoords as seen above): Java: for(int i = 0; i<vertices.length; i++){ Vector2f coord = new Vector2f((vertices[i].x)/(worldSize), (vertices[i].z)/( worldSize)); texCoords[i] = coord; } the quad used for input here rests on the X0Z plane. 'worldSize' is the diameter of the planet. No negative texCoords are seen as the quad used for input for this method is not centered around the origin. Is there something I am missing here? Thanks.

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  • Making particle bounce off a line with friction

    - by Dlaor
    So I'm making a game and I need a particle to bounce off a line. I've got this so far: public static Vector2f Reflect(this Vector2f vec, Vector2f axis) //vec is velocity { Vector2f result = vec - 2f * axis * axis.Dot(vec); return result; } Which works fine, but then I decided I wanted to be able to change the bounciness and friction of the bounce. I got bounciness down... public static Vector2f Reflect(this Vector2f vec, Vector2f axis, float bounciness) //Bounciness goes from 0 to 1, 0 being not bouncy and 1 being perfectly bouncy { var reflect = (1 + bounciness); //2f Vector2f result = vec - reflect * axis * axis.Dot(vec); return result; } But when I tried to add friction, everything went to hell and back... public static Vector2f Reflect(this Vector2f vec, Vector2f axis, float bounciness, float friction) //Does not work at all! { var reflect = (1 + bounciness); //2f Vector2f subtract = reflect * axis * axis.Dot(vec); Vector2f subtract2 = axis * axis.Dot(vec); Vector2f result = vec - subtract; result -= axis.PerpendicularLeft() * subtract2.Length() * friction; return result; } Any physics guys willing to help me out with this? (if you're not sure what I mean with the friction of a bounce see this: http://www.metanetsoftware.com/technique/diagrams/A-1_particle_collision.swf)

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  • Are long methods always bad?

    - by wobbily_col
    So looking around earlier I noticed some comments about long methods being bad practice. I am not sure I always agree that long methods are bad (and would like opinions from others). For example I have some Django views that do a bit of processing of the objects before sending them to the view, a long method being 350 lines of code. I have my code written so that it deals with the paramaters - sorting / filtering the queryset, then bit by bit does some processing on the objects my query has returned. So the processing is mainly conditional aggregation, that has complex enough rules it can't easily be done in the database, so I have some variables declared outside the main loop then get altered during the loop. varaible_1 = 0 variable_2 = 0 for object in queryset : if object.condition_condition_a and variable_2 > 0 : variable 1+= 1 ..... ... . more conditions to alter the variables return queryset, and context So according to the theory I should factor out all the code into smaller methods, so That I have the view method as being maximum one page long. However having worked on various code bases in the past, I sometimes find it makes the code less readable, when you need to constantly jump from one method to the next figuring out all the parts of it, while keeping the outermost method in your head. I find that having a long method that is well formatted, you can see the logic more easily, as it isn't getting hidden away in inner methods. I could factor out the code into smaller methods, but often there is is an inner loop being used for two or three things, so it would result in more complex code, or methods that don't do one thing but two or three (alternatively I could repeat inner loops for each task, but then there will be a performance hit). So is there a case that long methods are not always bad? Is there always a case for writing methods, when they will only be used in one place?

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  • Is there a canonical source supporting "all-surrogates"?

    - by user61852
    Background The "all-PK-must-be-surrogates" approach is not present in Codd's Relational Model or any SQL Standard (ANSI, ISO or other). Canonical books seems to elude this restrictions too. Oracle's own data dictionary scheme uses natural keys in some tables and surrogate keys in other tables. I mention this because these people must know a thing or two about RDBMS design. PPDM (Professional Petroleum Data Management Association) recommend the same canonical books do: Use surrogate keys as primary keys when: There are no natural or business keys Natural or business keys are bad ( change often ) The value of natural or business key is not known at the time of inserting record Multicolumn natural keys ( usually several FK ) exceed three columns, which makes joins too verbose. Also I have not found canonical source that says natural keys need to be immutable. All I find is that they need to be very estable, i.e need to be changed only in very rare ocassions, if ever. I mention PPDM because these people must know a thing or two about RDBMS design too. The origins of the "all-surrogates" approach seems to come from recommendations from some ORM frameworks. It's true that the approach allows for rapid database modeling by not having to do much business analysis, but at the expense of maintainability and readability of the SQL code. Much prevision is made for something that may or may not happen in the future ( the natural PK changed so we will have to use the RDBMS cascade update funtionality ) at the expense of day-to-day task like having to join more tables in every query and having to write code for importing data between databases, an otherwise very strightfoward procedure (due to the need to avoid PK colisions and having to create stage/equivalence tables beforehand ). Other argument is that indexes based on integers are faster, but that has to be supported with benchmarks. Obviously, long, varying varchars are not good for PK. But indexes based on short, fix-length varchar are almost as fast as integers. The questions - Is there any canonical source that supports the "all-PK-must-be-surrogates" approach ? - Has Codd's relational model been superceded by a newer relational model ?

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  • How to pass one float as four unsigned chars to shader by glVertexPointAttrib?

    - by Kog
    For each vertex I use two floats as position and four unsigned bytes as color. I want to store all of them in one table, so I tried casting those four unsigned bytes to one float, but I am unable to do that correctly... All in all, my tests came to one point: GLfloat vertices[] = { 1.0f, 0.5f, 0, 1.0f, 0, 0 }; glEnableVertexAttribArray(0); glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), vertices); // VER1 - draws red triangle // unsigned char colors[] = { 0xff, 0, 0, 0xff, 0xff, 0, 0, 0xff, 0xff, 0, 0, // 0xff }; // glEnableVertexAttribArray(1); // glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), // colors); // VER2 - draws greenish triangle (not "pure" green) // float f = 255 << 24 | 255; //Hex:0xff0000ff // float colors2[] = { f, f, f }; // glEnableVertexAttribArray(1); // glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), // colors2); // VER3 - draws red triangle int i = 255 << 24 | 255; //Hex:0xff0000ff int colors3[] = { i, i, i }; glEnableVertexAttribArray(1); glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), colors3); glDrawArrays(GL_TRIANGLES, 0, 3); Above code is used to draw one simple red triangle. My question is - why do versions 1 and 3 work correctly, while version 2 draws some greenish triangle? Hex values are one I read by marking variable during debug. They are equal for version 2 and 3 - so what causes the difference?

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  • Is the way I'm implementing my genetic algorithm right?

    - by Mhjr
    In my graduation project, I am asked to use a genetic algorithm (any variation of it can be chosen) to generate valid timetables. What I did was make a simple program that generates unique sequences representing genes, the sequence is described below: (sorry if it's mathematically incorrect) The only variable in the sequence is the room element, so basically the program takes a tree that goes like this: [Course] -(contains)-> [Units] -(contains)-> [Offerings] -(contains)-> [Instructors] -(contains)-> [Rooms] Each course can have n units (duplicates). Each unit can have n offerings (lectures,lab session, excercises,...). Each offering has only 1 instructor. Each instructor (or the whole lecture composed from the four elements of the sequence) has multiple rooms. When a timetable is initialized, one of these sequences that differ in rooms will be taken into the timetable, so the difference in genes (sequences) of each timetable will be just the rooms random choice and the difference between chromosomes (timetables) will be time placements of these genes (sequences). My question is, before I proceed in implementing what I described, is it valid? Is the representation used here for chromosomes a permutation representation?

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  • How can I get cross-browser consistent behavior for TR heights within a table with a set height? [migrated]

    - by Dan
    I have an arbitrary number of tables with an arbitrary number of rows in each, and all tables are the same height. My initial approach was to just set the overall height of the table and hope the rows were smart enough to distribute themselves appropriately. That's not the case. I have 4 different behaviors going on with 4 browsers, but I need them to all render at the very least in a similar way. Safari & Chrome (WebKit): All rows are equal height, creating scroll bars as needed and fitting within table height. Firefox: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Additionally, If the content of the rows does not take up all of the height, only the part of the table with content in it takes the background (though it seems, through use of Firebug, that the actual table [and TR] extend to the bottom of the proper table height). IE: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Obviously this only includes one version of each browser and additional variation would likely appear with more being tested. Ideally, a solution where the browser renders TRs with less content smaller than those with larger content, while still using scrolling within the variable height TRs when the overall height of the table is not enough would be optimum. I could potentially see a solution to achieve that with JS, but can it be done with CSS? Or, if not, can the behavior that WebKit displays be made to work across the browsers? Thanks! PS: Example can be found here.

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  • Visually and audibly unambiguous subset of the Latin alphabet?

    - by elliot42
    Imagine you give someone a card with the code "5SBDO0" on it. In some fonts, the letter "S" is difficult to visually distinguish from the number five, (as with number zero and letter "O"). Reading the code out loud, it might be difficult to distinguish "B" from "D", necessitating saying "B as in boy," "D as in dog," or using a "phonetic alphabet" instead. What's the biggest subset of letters and numbers that will, in most cases, both look unambiguous visually and sound unambiguous when read aloud? Background: We want to generate a short string that can encode as many values as possible while still being easy to communicate. Imagine you have a 6-character string, "123456". In base 10 this can encode 10^6 values. In hex "1B23DF" you can encode 16^6 values in the same number of characters, but this can sound ambiguous when read aloud. ("B" vs. "D") Likewise for any string of N characters, you get (size of alphabet)^N values. The string is limited to a length of about six characters, due to wanting to fit easily within the capacity of human working memory capacity. Thus to find the max number of values we can encode, we need to find that largest unambiguous set of letters/numbers. There's no reason we can't consider the letters G-Z, and some common punctuation, but I don't want to have to go manually pairwise compare "does G sound like A?", "does G sound like B?", "does G sound like C" myself. As we know this would be O(n^2) linguistic work to do =)...

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  • Particle trajectory smoothing: where to do the simulation?

    - by nkint
    I have a particle system in which I have particles that are moving to a target and the new targets are received via network. The list of new target are some noisy coordinates of a moving target stored in the server that I want to smooth in the client. For doing the smoothing and the particle I wrote a simple particle engine with standard euler integration model. So, my pseudo code is something like that: # pseudo code class Particle: def update(): # do euler motion model integration: # if the distance to the target is more than a limit # add a new force to the accelleration # seeking the target, # and add the accelleration to velocity # and velocity to the position positionHistory.push_back(position); if history.length > historySize : history.pop_front() class ParticleEngine: particleById = dict() # an associative array # where the keys are the id # and particle istances are sotred as values # this method is called each time a new tcp packet is received and parsed def setNetTarget(int id, Vec2D new_target): particleById[id].setNewTarget(new_target) # this method is called each new frame def draw(): for p in particleById.values: p.update() beginVertex(LINE_STRIP) for v in p.positionHistory: vertex(v.x, v.y) endVertex() The new target that are arriving are noisy but setting some accelleration/velocity parameters let the particle to have a smoothed trajectories. But if a particle trajectory is a circle after a while the particle position converge to the center (a normal behaviour of euler integration model). So I decided to change the simulation and use some other interpolation (spline?) or smooth method (kalman filter?) between the targets. Something like: switch( INTERPOLATION_MODEL ): case EULER_MOTION: ... case HERMITE_INTERPOLATION: ... case SPLINE_INTERPOLATION: ... case KALMAN_FILTER_SMOOTHING: ... Now my question: where to write the motion simulation / trajectory interpolation? In the Particle? So I will have some Particle subclass like ParticleEuler, ParticleSpline, ParticleKalman, etc..? Or in the particle engine?

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  • Most efficient Implementation a Tree in C++

    - by Topo
    I need to write a tree where each element may have any number of child elements, and because of this each branch of the tree may have any length. The tree is only going to receive elements at first and then it is going to use exclusively for iterating though it's branches in no specific order. The tree will have several million elements and must be fast but also memory efficient. My plan makes a node class to store the elements and the pointers to its children. When the tree is fully constructed, it would be transformed it to an array or something faster and if possible, loaded to the processor's cache. Construction and the search on the tree are two different problems. Can I focus on how to solve each problem on the best way individually? The construction of has to be as fast as possible but it can use memory as it pleases. Then the transformation into a format that give us speed when iterating the tree's branches. This should preferably be an array to avoid going back and forth from RAM to cache in each element of the tree. So the real question is which is the structure to implement a tree to maximize insert speed, how can I transform it to a structure that gives me the best speed and memory?

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  • Estimate angle to launch missile, maths question

    - by Jonathan
    I've been working on this for an hour or two now and my maths really isn't my strong suit which is definitely not a good thing for a game programmer but that shouldn't stop me enjoying a hobby surely? After a few failed attempts I was hoping someone else out there could help so here's the situation. I'm trying to implement a bit of faked intelligence when the A.I fires it's missiles at a target in a 2D game world. By predicting the likely position the target will be in given it's current velocity and the time it will take the missile to reach it's target. I created an image to demonstrate my thinking: http://i.imgur.com/SFmU3.png which also contains the logic I use for accelerating the missile after launch. The ship that fires the missile can fire within a total of 40 degree angle, 20 either side of itself, but this could likely become variable. My current attempt was to break the space between the two lines into segments which match the targets width. Then calculate the time it would take the missile to get to that location using the formula. So for each iteration of this we total up the values and that tells us the distance travelled, ad it would then just need compared to distance to the segment. startVelocity * ((startVelocity * acceleration)^(currentframe-1) So for example. If we start at a velocity of 1f/frame with an acceleration of 0.1f the formula, at frame 4, would be 1 * (1.1^3) = 1.331 But I quickly realized I was getting lost when trying to put this into practice. Does this seem like a correct starting point or am I going completely the wrong way about it? Any pointers would help me greatly. Maths really isn't my strong suit so I get easily lost in these matters and don't even really know a good phrase to search for with this. So I guess in summary my question is more about the correct way to approach this problem and any additional code samples on top of that would be great but I'm not averse to working out the complete code from helpful pointers.

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  • questions on a particular algorithm

    - by paul smith
    Upon searching for a fast primr algorithm, I stumbled upon this: public static boolean isP(long n) { if (n==2 || n==3) return true; if ((n&0x1)==0 || n%3==0 || n<2) return false; long root=(long)Math.sqrt(n)+1L; // we check just numbers of the form 6*k+1 and 6*k-1 for (long k=6;k<=root;k+=6) { if (n%(k-1)==0) return false; if (n%(k+1)==0) return false; } return true; } My questions are: Why is long being used everywhere instead of int? Because with a long type the argument could be much larger than Integer.MAX thus making the method more flexible? In the second 'if', is n&0x1 the same as n%2? If so why didn't the author just use n%2? To me it's more readable. The line that sets the 'root' variable, why add the 1L? What is the run-time complexity? Is it O(sqrt(n/6)) or O(sqrt(n)/6)? Or would we just say O(n)?

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  • "Can't open display" even after access with xhost

    - by Yann
    I'm trying to run a graphical program remotely, without using ssh. I've set the display variable on the server (let's say server.com, Linux, not ubuntu, and no su rights) to point to my workstation (workstation.com, ubuntu 10.04) setenv DISPLAY workstation.com:0 Then on my workstation I've tried both xhost +server.com and xhost + Then I ssh into the server (to test things): ssh [email protected] and try to run xclock, and get the following error: Error: Can't open display: workstation.com:0 I've looked at /etc/ssh/ssh_config on the workstation and I should be forwarding correctly: X11Forwarding yes. How do I go about troubleshooting this? What logs on the workstation document these failed attempts? To explain why I'm doing this: I want to run a batch job on a server to debug an MPI-based parallel program. I want to run xterm as the batch job executable, per the instructions provided by the system admins. This setup use to work. I reinstalled things on my workstation and since then I frequently get one-time message along the lines The authenticity of host 'hostname (XXX.XXX.XXX.XX)' can't be established. My attempt to fix the above was to move my ~/.ssh/known_hosts file to a back up on both server and host, and then to ssh from each to the other with the flag -o StrictHostKeyChecking=no. I no longer get that message, but I was wondering does this play a part in why X11 forwarding is not working?

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  • Strategies for managing use of types in Python

    - by dave
    I'm a long time programmer in C# but have been coding in Python for the past year. One of the big hurdles for me was the lack of type definitions for variables and parameters. Whereas I totally get the idea of duck typing, I do find it frustrating that I can't tell the type of a variable just by looking at it. This is an issue when you look at someone else's code where they've used ambiguous names for method parameters (see edit below). In a few cases, I've added asserts to ensure parameters comply with an expected type but this goes against the whole duck typing thing. On some methods, I'll document the expected type of parameters (eg: list of user objects), but even this seems to go against the idea of just using an object and let the runtime deal with exceptions. What strategies do you use to avoid typing problems in Python? Edit: Example of the parameter naming issues: If our code base we have a task object (ORM object) and a task_obj object (higher level object that embeds a task). Needless to say, many methods accept a parameter named 'task'. The method might expect a task or a task_obj or some other construct such as a dictionary of task properties - it is not clear. It is them up to be to look at how that parameter is used in order to work out what the method expects.

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  • How do I fix broken installation?

    - by Daniel
    Let me start off by saying I'm dual booting 11.04 and Windows 7 on a Thinkpad T61p. The problem may have arisen when I hit the power button during normal startup. I'm fully aware how stupid this is. I don't know why I did it. I did it. Now, I can't get in to Ubuntu. Windows works fine. But when I try to start Ubuntu normally, it seems to run some checks, and does not start up. Sometimes, I see a black screen, and it tells me that it's running certain checks, and then, [ok]. Like... Battery Check Somethingorother [ok] It'll give me 1-5 of these. And then it just does nothing, and I have to turn it off. When I try to start in safe mode... I tried low graphics mode, and after going through a couple of dialogue boxes, I'm brought right back to the safe mode dialogue box. And if I hit 'resume,' a shell pushes up (still that grey on black "your computer is broken" type shell) and asks me to log in. I do, and try to run unity. It tells me something along the lines of: WARNING no DISPLAY variable set and then sets it to " :0" , which doesn't work. And then I can't do anything, really, and I have to restart. (I don't know how to do this from the command line, so I just hard reset. That command would be helpful). Does anybody have any idea how I can get Ubuntu working right again? FTP is less pleasant in Explorer than it is in Nautilus or w/e it is now.

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  • Package libxul not fount - Kiwix Wikpedia in Ubuntu Precise 12.04

    - by JHOSmAN
    I'm trying to install the service Kiwix but I need a library that is not available for Ubuntu 12.04 LTS Precise leave the log and if someone could tell me how to install Seller would appreciate. kiwix-0.9# ls aclocal.m4 COMPILE config.sub COPYING install-sh ltmain.sh missing static AUTHORS config.guess configure depcomp kiwix Makefile.am README CHANGELOG config.log configure.ac desktop libxul-dev_1.8.1.16+nobinonly-0ubuntu1_all.deb Makefile.in src root@ubuntu-MM061:/home/ubuntu/Escritorio/kiwix-0.9# ./configure checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... no checking for mawk... mawk checking whether make sets $(MAKE)... yes checking whether to enable maintainer-specific portions of Makefiles... no checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking for style of include used by make... GNU checking dependency style of gcc... gcc3 checking for g++... g++ checking whether we are using the GNU C++ compiler... yes checking whether g++ accepts -g... yes checking dependency style of g++... gcc3 checking for g++... g++ checking for cl... no checking for cl... no checking for Xcode... no checking for jar... jar checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking for a sed that does not truncate output... /bin/sed checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for fgrep... /bin/grep -F checking for ld used by gcc... /usr/bin/ld checking if the linker (/usr/bin/ld) is GNU ld... yes checking for BSD- or MS-compatible name lister (nm)... /usr/bin/nm -B checking the name lister (/usr/bin/nm -B) interface... BSD nm checking whether ln -s works... yes checking the maximum length of command line arguments... 1572864 checking whether the shell understands some XSI constructs... yes checking whether the shell understands "+="... yes checking for /usr/bin/ld option to reload object files... -r checking for objdump... objdump checking how to recognize dependent libraries... pass_all checking for ar... ar checking for strip... strip checking for ranlib... ranlib checking command to parse /usr/bin/nm -B output from gcc object... ok checking how to run the C preprocessor... gcc -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking for dlfcn.h... yes checking whether we are using the GNU C++ compiler... (cached) yes checking whether g++ accepts -g... (cached) yes checking dependency style of g++... (cached) gcc3 checking how to run the C++ preprocessor... g++ -E checking for objdir... .libs checking if gcc supports -fno-rtti -fno-exceptions... no checking for gcc option to produce PIC... -fPIC -DPIC checking if gcc PIC flag -fPIC -DPIC works... yes checking if gcc static flag -static works... yes checking if gcc supports -c -o file.o... yes checking if gcc supports -c -o file.o... (cached) yes checking whether the gcc linker (/usr/bin/ld) supports shared libraries... yes checking whether -lc should be explicitly linked in... no checking dynamic linker characteristics... GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... yes checking for ld used by g++... /usr/bin/ld checking if the linker (/usr/bin/ld) is GNU ld... yes checking whether the g++ linker (/usr/bin/ld) supports shared libraries... yes checking for g++ option to produce PIC... -fPIC -DPIC checking if g++ PIC flag -fPIC -DPIC works... yes checking if g++ static flag -static works... yes checking if g++ supports -c -o file.o... yes checking if g++ supports -c -o file.o... (cached) yes checking whether the g++ linker (/usr/bin/ld) supports shared libraries... yes checking dynamic linker characteristics... GNU/Linux ld.so checking how to hardcode library paths into programs... immediate checking for ranlib... (cached) ranlib checking whether make sets $(MAKE)... (cached) yes checking for pkg-config... pkg-config checking for perl... perl checking fcntl.h usability... yes checking fcntl.h presence... yes checking for fcntl.h... yes checking float.h usability... yes checking float.h presence... yes checking for float.h... yes checking libintl.h usability... yes checking libintl.h presence... yes checking for libintl.h... yes checking limits.h usability... yes checking limits.h presence... yes checking for limits.h... yes checking stddef.h usability... yes checking stddef.h presence... yes checking for stddef.h... yes checking for stdint.h... (cached) yes checking for stdlib.h... (cached) yes checking for string.h... (cached) yes checking for strings.h... (cached) yes checking sys/socket.h usability... yes checking sys/socket.h presence... yes checking for sys/socket.h... yes checking sys/time.h usability... yes checking sys/time.h presence... yes checking for sys/time.h... yes checking for unistd.h... (cached) yes checking wchar.h usability... yes checking wchar.h presence... yes checking for wchar.h... yes checking for stdbool.h that conforms to C99... yes checking for _Bool... no checking for inline... inline checking for int16_t... yes checking for int32_t... yes checking for int64_t... yes checking for int8_t... yes checking for off_t... yes checking for pid_t... yes checking for size_t... yes checking for uint16_t... yes checking for uint32_t... yes checking for uint64_t... yes checking for uint8_t... yes checking for ptrdiff_t... yes checking vfork.h usability... no checking vfork.h presence... no checking for vfork.h... no checking for fork... yes checking for vfork... yes checking for working fork... yes checking for working vfork... (cached) yes checking for stdlib.h... (cached) yes checking for GNU libc compatible malloc... yes checking for working strtod... yes checking for getcwd... yes checking for gettimeofday... yes checking for memmove... yes checking for memset... yes checking for pow... yes checking for regcomp... yes checking for sqrt... yes checking for strcasecmp... yes checking for strchr... yes checking for strdup... yes checking for strerror... yes checking for strtol... yes Package libxul was not found in the pkg-config search path. Perhaps you should add the directory containing libxul.pc' to the PKG_CONFIG_PATH environment variable No package 'libxul' found Package libxul was not found in the pkg-config search path. Perhaps you should add the directory containinglibxul.pc' to the PKG_CONFIG_PATH environment variable No package 'libxul' found checking for /stable... no checking for "/nsISupports.idl"... no configure: error: unable to find nsISupports.idl apt-get install libxul Leyendo lista de paquetes... Hecho Creando árbol de dependencias Leyendo la información de estado... Hecho E: No se ha podido localizar el paquete libxul

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