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  • Automated texture mapping

    - by brandon
    I have a set of seamless tiling textures. I want to be able to take an arbitrary model and create a UV map with these properties: No stretching (all textures tile appropriately so there is no stretching and sheering of the texture) The textures display on the correct axis relative to the model it's mapping to (if you look at the example, you can see some of the letters on the front are tilted, the y axis of the texture should be matching up with the y axis of the object. Some other faces have upside down letters too) the texture is as continuous as possible on the surface of the model (if two faces are adjacent, the texture continues on the adjacent face where it left off) the model is closed (all faces are completely enclosed by other faces) A few notes. This mapping will occur before triangulation. I realize there are ways to do this by hand and it's probably a hard problem to automatically map textures in general, but since these textures are seamless and I just need uniform coverage it seems like an easier problem. I'm looking for an algorithmic approach to this that I can apply in general, not a tool that does it. What approach would work for this, is there an existing one? (I assume so)

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  • XNA - Finding boundaries in isometric tilemap

    - by Yheeky
    I have an issue with my 2D isometric engine. I'm using my own 2D camera class which works with matrices and need to find the tilemaps boundaries so the user always sees the map. Currently my map size is 100x100 (with 128x128 tiles) so the calculation (e.g. for the right boundary) is: var maxX = (TileMap.MapWidth + 1) * (TileMap.TileWidth / 2) - ViewSize.X; var maxX = (100 + 1) * (128 / 2) - 1360; // = 5104 pixels. This works fine while having scale factor of 1.0f but not for any other zoom factor. When I zoom out to 0.9f the right border should be at approx. 4954. I´m using the following code for transformation but I always get a wrong value: var maxXVector = new Vector2(maxX, 0); var maxXTransformed = Vector2.Transform(maxXVector, tempTransform).X; The result is 4593. Does anyone of you have an idea what I´m during wrong? Thanks for your help! Yheeky

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  • Feasability of mobile 2D multiplayer RPG game with interactive bitmap background

    - by user2827214
    I'm looking to develop a 2D multiplayer RPG game for Android, with a bird's eye view similar to that of zelda/pokemon. The game is very simple in all ways since my intent is for thousands of players to occupy the same world which I imagine requires good performance. However, I am unsure about the performance requirements of two properties: the tile map that is used as a background is dynamic (interactive). For example, a player steps in the water, and the water turns black. Every tile in the game does this. the tile map is the same object used for all players, but it is displayed differently on each user's mobile device, even though the players exist in the same world. For example, the water that turned black is displayed as red on all other players' screens. I have knowledge of java, but almost none regarding game dev. tools. Is there a best process for these requirements? Should I develop in pure java, or use some tool like Slick2D etc.? How performance intensive are these properties, if even possible? Edit: There are no collisions in the game or difficult animations, I am imagining simply changing the colors of the tiles (like in the examples), and a client-server architecture

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  • Difficulty / Process for mobile 2D multiplayer RPG game

    - by user2827214
    I'm looking to develop a 2D multiplayer RPG game for Android, with a bird's eye view similar to that of zelda/pokemon. The game is very simple in all ways since my intent is for thousands of players to occupy the same world which I imagine requires good performance. However, I am unsure about the performance requirements of two properties: the tile map that is used as a background is dynamic (interactive). For example, a player steps in the water, and the water turns black. Every tile in the game does this. the tile map is the same object used for all players, but it is displayed differently on each user's mobile device, even though the players exist in the same world. For example, the water that turned black is displayed as red on all other players' screens. I have knowledge of java, but almost none regarding game dev. tools. Is there a best process for these requirements? Should I develop in pure java, or use some tool like Slick2D etc.? How performance intensive are these properties, if even possible? Edit: There are no collisions in the game or difficult animations, I imagining simply changing colors of the tiles like in the examples, and a client-server architecture

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  • Doubling the DPI with a shader?

    - by Mathias Lykkegaard Lorenzen
    I'm developing a game where the map is generated with Perlin Noise, but on the CPU. I am generating some perlin noise onto a texture with a small size, and then I stretch it out to the whole screen to simulate a map. The reason for the CPU generating the noise is that I want it to look the same on all devices. Now, here's the end-result. Please ignore the bullets and the explosion on the picture. What matters is the background (the black/gray pixels) and the ground (the brown-ish pixels). They are rendered to the same texture through perlin noise. However, this doesn't look very pretty. So I was wondering if it would be possible to double the amount of pixels using a shader, and rounding edges at the same time? In other words, improve the DPI. I'm using SharpDX with DirectX 11, through its toolkit feature. But any help that'll lead me in the right direction (for instance through HLSL) would be a great help. Thanks in advance.

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  • geomipmapping using displacement mapping (and glVertexAttribDivisor)

    - by Will
    I wake up with a clear vision, but sadly my laptop card doesn't do displacement mapping nor glVertexAttribDivisor so I can't test it out; I'm left sharing here: With geomipmapping, the grid at any factor is transposable - if you pass in an offset - say as a uniform - you can reuse the same vertex and index array again and again. If you also pass in the offset into the heightmap as a uniform, the vertex shader can do displacement mapping. If the displacement map is mipmapped, you get the advantages of trilinear filtering for distant maps. And, if the scenery is closer, rather than exposing that the you have a world made out of quads, you can use your transposable grid vertex array and indices to do vertex-shader interpolation (fancy splines) to do super-smooth infinite zoom? So I have some questions: does it work? In theory, in practice? does anyone do it? Does this technique have a name? Papers, demos, anything I can look at? does glVertexAttribDivisor mean that you can have a single glMultiDrawElementsEXT or similar approach to draw all your terrain tiles in one call rather than setting up the uniforms and emitting each tile? Would this offer any noticeable gains? does a heightmap that is GL_LUMINANCE take just one byte per pixel(=vertex)? (On mainstream cards, obviously. Does storage vary in practice?) Does going to the effort of reusing the same vertices and indices mean that you can basically fill the GPU RAM with heightmap and not a lot else, giving you either bigger landscapes or more detailed landscapes/meshes for the same bang? is mipmapping the displacement map going to work? On future cards? Is it going to introduce unsurmountable inaccuracies if it is enabled?

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  • Should I make the Cells in a Tiledmap as null when my player hits it

    - by Vishal Kumar
    I am making a Tile Based game using Libgdx. I took the idea from SuperKoalio platformer demo by Mario Zencher. When I wanted to implement Collectables in my game , I simply draw the coins using Tiled Map Editor. When my player hits that, I use to set that cell as null. Someday on this site suggested me not to do so... never use null. I agreed. What can be any other way. If I am using layer.setCell(x,y) to set the cell to any other cell... even if an transparent one .. my player seems to be stopped by an invisible object/hurdle. This is my code: for (Rectangle tile : tiles) { if (koalaRect.overlaps(tile)) { TiledMapTileLayer layer = (TiledMapTileLayer) map.getLayers().get(1); try{ type = layer.getCell((int) tile.x, (int) tile.y).getTile().getProperties().get("tileType").toString(); } catch(Exception e){ System.out.print("Exception in Tiles Property"+e); type="nonbreakable"; } //Let us destroy this cell if(("award".equals(type))){ layer.setCell((int) tile.x, (int) tile.y, null); listener.coin(); score+=100; test = ""+layer.getCell(0, 0).getTile().getProperties().get("tileType"); } //DOING THIS GIVES A BAD EFFECT if(("killer".equals(type))){ //player.health--; //layer.setCell((int) tile.x, (int) tile.y, layer.getCell(20,0)); } // we actually reset the player y-position here // so it is just below/above the tile we collided with // this removes bouncing :) if (player.velocity.y > 0) { player.position.y = (tile.y - Player.height); } Is this a right approach? OR I should create separate Sprite Class called Coin.

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  • Detecting Units on a Grid

    - by hammythepig
    I am making a little turn based strategy game in pygame, that uses a grid system as the main map to hold all the characters and the map layout. (Similar to Fire Emblem, or Advance Wars) I am trying to determine a way to quickly and efficiently (i.e. without too much of a slow down) check if there are any characters within a given range of the currently selected character. So to illustrate: O = currently selected character X = squares within range Range of 1: X X O X X Range of 2: X X X X X X O X X X X X X Range of 3: X X X X X X X X X X X X O X X X X X X X X X X X X Now I have to tell the user who is in range, and I have to let the user choose who to attack if there are multiple enemies in range. If I have a 5x5 grid, filled with " " for empty and numbers for the characters: [ ][ ][ ][ ][4] [ ][1][ ][ ][ ] [ ][ ][ ][ ][ ] [ ][ ][2][3][ ] [ ][ ][ ][ ][ ] Depending on which character the user selects, I would like to show the user which other characters are in range. So if they all had a range of 3: 1 can hit 2 2 can hit 1 or 3 3 can hit 2 4 cannot hit anyone. So, How do I quickly and/or efficiently run though my grid and tell the user where the enemies are? PS- As a bonus, if someone could give an answer that could also work for a minimum distance type range, I would give them a pat on the back and a high five, should they ever travel to Canada and we ever meet in life. For example: Range of 3 to 5: (- is out of range) X X X X X X X X X X X X - X X X X X X - - - X X X X X X - - O - - X X X X X X - - - X X X X X X - X X X X X X X X X X X X

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  • Collision Detection for a 2D RPG

    - by PHMitrious
    First of all, I have done some research on this topic before asking, and I'm asking this question as a mean to get some opinions on this topic, so I don't make a decision only on my own, but taking into account other people's experience as well. I'm starting a 2D online RPG project. I am using SFML for graphics and input and I'm creating a basic game structure and all for the game, creating modules for each part of the game. Well, let me get to the point I just wanted to give you guys some context. I want to decide on how I'm going to work with collision detection. Well I'm kinda going to work on maps with a tile map divided in layers (as usual) and add an extra 2 layers - not exactly in the map - for objects. So I'll have collisions between objects and agents (players - npcs - monsters - spells etc) and agents and tiles. The seconds one can be easily solved the first one need a little bit of work. I considered both creating a basic collision test engine using polygons and a quadtree to diminish tests since I'm going to be working with big maps with lots of objects - creating both a physical and graphical world representation. And I also considered using a physics engine like Box2D for collision tests. I think the first approach would take more work on my part but the second one would have the overhead of using a whole physics engine for just collision detection and no physics. What do you guys think ?

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  • Returning Value of Radio Button Jquery [migrated]

    - by Jerry Walker
    I am trying to figure out why, when I run this code, I am getting undefined for my correct answers. $(document).ready (function () { // var answers = [["Fee","Fi","Fo"], ["La","Dee","Da"]], questions = ["Fee-ing?", "La-ing?"], corAns = ["Fee", "La"]; var counter = 0; var $facts = $('#main_ .facts_div'), $question = $facts.find('.question'), $ul = $facts.find('ul'), $btn = $('.myBtn'); $btn.on('click', function() { if (counter < questions.length) { $question.text(questions[counter]); var ansstring = $.map(answers[counter], function(value) { return '<li><input type="radio" name="ans" value="0"/>' + value + '</li>'}).join(''); $ul.html(ansstring); var currentAnswers = $('input[name="ans"]:checked').map(function() { return this.val(); }).get(); var correct = 0; if (currentAnswers[counter]==corAns[counter]) { correct++; } } else { $facts.text('You are done with the quiz ' + correct); $(this).hide(); } counter++; }); // }); It is quite long and I'm sorry about that, but I don't really know how tostrip it down. I also realize this isn't the most elegant way to do this, but I just want to know why I can't seem to get my radio values. I will add the markup as well if anyone wants.

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  • Implmenting RLE into a tilemap or how to create a large 3D array?

    - by Smallbro
    Currently I've been using a 3D array for my tiles in a 2D world but the 3D side comes in when moving down into caves and whatnot. Now this is not memory efficient and I switched over to a 2D array and can now have much larger maps. The only issue I'm having now is that it seems that my tiles cannot occupy the same space as a tile on the same z level. My current structure means that each block has its own z variable. This is what it used to look like: map.blockData[x][y][z] = new Block(); however now it works like this map.blockData[x][y] = new Block(z); I'm not sure why but if I decide to use the same space on say the floor below it wont allow me to. Does anyone have any ideas on how I can add a z-axis to my 2D array? I'm using java but I reckon the concept carries across different languages. Edit: As Will posted, RLE sounds like the best method for achieving a fast 3D array. However I'm struggling to understand how I would even start to implement it? Would I create a 4D array the 4th being something which controls how many to skip? Or would the x-axis simply change altogether and have large gaps in between - for example [5][y][z] would skip 5 tiles? Is there something really obvious here which I am missing? The number of z levels I'm trying to have is around 66, it would be preferably that I can have up to or more than 1000 in x and y.

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  • Libgdx ParallaxScrolling and TiledMaps

    - by kirchhoff
    I implemented ParallaxScrolling for my SideScroller project, everything is working but the tiled map (the most important part!). I've been trying out everything but it doesn't work (see the code below). I'm using ParallaxCamera from GdxTests, it's working perfectly for the background layers. I can't explain myself properly in english, so I recorded 2 videos: Before parallaxScrolling After parallaxScrolling As you can see, now the platforms appear in the middle of the Y-axis. I've got a Map class with 2 tiled maps, so I need two renderers too: private TiledMapRenderer renderer1; private TiledMapRenderer renderer2; public void update(GameCamera camera) { renderer1.setView(camera.calculateParallaxMatrix(1f, 0f), camera.position.x - camera.viewportWidth / 2, **camera.position.y - camera.viewportHeight/2**, camera.viewportWidth, camera.viewportHeight); renderer2.setView(camera.calculateParallaxMatrix(1f, 0f), camera.position.x - camera.viewportWidth / 2, **camera.position.y - camera.viewportHeight/2**, camera.viewportWidth, camera.viewportHeight); } In bold, the code I think I should change. I've tried changing parameters, even adding hardcoded values, etc, but one of two: 1. Nothing happens. 2. Platforms disappear. Here is some aditional code. The render method: world.update(delta); parallaxBackground.update(camera); clear(0.5f, 0.7f, 1.0f, 1); batch.setProjectionMatrix(camera.calculateParallaxMatrix(0, 0)); batch.disableBlending(); batch.begin(); batch.draw(background, -(int)background.getRegionWidth()/2, -(int)background.getRegionHeight()/2); batch.end(); batch.enableBlending(); parallaxBackground.draw(batch, camera); renderer.render(batch);

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  • Why is Javascript used in MongoDB and CouchDB instead of other languages such as Java, C++?

    - by startup007
    I asked this question on SO but was suggested to try here. So here it goes: My understanding of Javascript so far has been that it is a client-side language that capture events and makes a web-page dynamic. But on reading the comparison between MongoDB and CouchDB I noticed that both are using Javascript. This makes me wonder the reason behind the choice of JavaScript over other conventional languages. I guess I am trying to understand the role of JavaScript and its advantages over other languages. Update: I am not asking about the languages / drivers supported by the two databases. The comparison says: Both CouchDB and MongoDB make use of Javascript. CouchDB uses Javascript extensively including in the building of views. MongoDB also supports running arbitrary javascript functions server-side and uses javascript for map/reduce operations. My lack of understanding pertains to why is Javascript being used at all for the backend work. Why is it preferred for building views in CouchDB, or for using map/reduce operations? Why C/C++ or Java were not used? What are the advantages in using Javascript for such back-end work?

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  • Precision loss when transforming from cartesian to isometric

    - by Justin Skiles
    My goal is to display a tile map in isometric projection. This tile map has 25 tiles across and 25 tiles down. Each tile is 32x32. See below for how I'm accomplishing this. World Space World Space to Screen Space Rotation (45 degrees) Using a 2D rotation matrix, I use the following: double rotation = Math.PI / 4; double rotatedX = ((tileWorldX * Math.Cos(rotation)) - ((tileWorldY * Math.Sin(rotation))); double rotatedY = ((tileWorldX * Math.Sin(rotation)) + (tileWorldY * Math.Cos(rotation))); World Space to Screen Space Scale (Y-axis reduced by 50%) Here I simply scale down the Y value by a factor of 0.5. Problem And it works, kind of. There are some tiny 1px-2px gaps between some of the tiles when rendering. I think there's some precision loss somewhere, or I'm not understanding how to get these tiles to fit together perfectly. I'm not truncating or converting my values to non-decimal types until I absolutely have to (when I pass to the render method, which only takes integers). I'm not sure how to guarantee pixel perfect rendering precision when I'm rotating and scaling on a level of higher precision. Any advice? Do I need to supply for information?

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  • How to highlight non-rectangular hotspots?

    - by HuseyinUslu
    So my question is highly related to Creating non-rectangular hotspots and detecting clicks. Yet again, I've irregular hot-spots (think the game Risk). So basically, we can detect clicks on these hot-spots easily using color key mapping as discussed in above question which I don't have any problems implementing (which is also covered here in details). The problem is about highlighting these irreguar hotspots. So let me explain the question a bit more - the above color key mapping guide uses this as a world map: Then the author color-maps the imaginary countries: Now we can now detect the country the pointer is over. In the same article author mentions outlining countries on mouse-over. Though to get the effect, he creates unique border assets for each country - like: For the game I'm working on I'm using the same color-key mapping idea to detect hot-spots, but I didn't like the way of highlighting hot-spots. Coloring all the hot-spots is already a time-consuming job for me - as I have 25+ hot-spots for each map. Further, the need to have 25 unique border/highlight asset per hot-spot doesn't sound right. Anyone have a better idea/suggestion on highlighting these hot-spots?

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  • Algorithm to reduce calls to mapping API

    - by aidan
    A random distribution of points lies on a map. This data lies behind an API, and I want to grab the complete set of points within a given bounding box. I can query the API with the bounding box and the API will return the set of points that fall within that box. The problem is that the API will limit the result set to 10 items, with no pagination and no indication if there are more points that have been omitted. So I made a recursive algorithm that takes a bounding box and requests the points that lie within it. If the result set is exactly 10 items, then I split the bounding box into four quadrants and recurse. It works fine but my question is this: if want to minimize the number of API calls, what is the optimal way to split the bounding box? Splitting it into quadrants was just an arbitrary decision. When there are a lot of points on the map, I have to drill down many levels before I start getting meaningful results. So I imagine it might be faster to split the box into, say, 9, 16, or more sections. But if I do that, then I eventually get to a point where a lot of requests are returning 0 results which isn't so efficient. Also, does the size of the limit on the results set affect the answer? (This is all assuming that I have no prior knowledge of nominal point density in the bounding box)

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  • Ubuntu 13.04 client cannot connect to Raspbian samba share

    - by envoyweb
    I have a client Ubuntu 13.04 machine trying to connect to a server running Raspbian with samba and samba-common-bin installed on the server I can see my share and when I try to login I get this error: Unable to access location: Failed to write windows share Cannot allocate memory. I have installed ntfs-3g for the usb hard drive that already auto mounts on the server so I never had to create a directory or edit fstab. Testparm on the server states the following: [global] workgroup = ENVOYWEB server string = %h server map to guest = Bad User obey pam restrictions = Yes pam password change = Yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . unix password sync = Yes syslog = 0 log file = /var/log/samba/log.%m max log size = 1000 dns proxy = No usershare allow guests = Yes panic action = /usr/share/samba/panic-action %d idmap config * : backend = tdb [homes] comment = Home Directories valid users = %S create mask = 0700 directory mask = 0700 browseable = No [printers] comment = All Printers path = /var/spool/samba create mask = 0700 printable = Yes print ok = Yes browseable = No [print$] comment = Printer Drivers path = /var/lib/samba/printers [BigDude] comment = Sharing BigDude's Files path = /media/BigDude/ valid users = @users read only = No create mask = 0755 testparm on the client which is running ubuntu is as follows [global] workgroup = ENVOYWEB server string = %h server (Samba, Ubuntu) map to guest = Bad User obey pam restrictions = Yes pam password change = Yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . unix password sync = Yes syslog = 0 log file = /var/log/samba/log.%m max log size = 1000 dns proxy = No usershare allow guests = Yes panic action = /usr/share/samba/panic-action %d idmap config * : backend = tdb [printers] comment = All Printers path = /var/spool/samba create mask = 0700 printable = Yes print ok = Yes browseable = No [print$] comment = Printer Drivers path = /var/lib/samba/printers

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  • Having troubles with LibNoise.XNA and generating tileable maps

    - by Jon
    Following up on my previous post, I found a wonderful port of LibNoise for XNA. I've been working with it for about 8 hours straight and I'm tearing my hair out - I just can not get maps to tile, I can't figure out how to do this. Here's my attempt: Perlin perlin = new Perlin(1.2, 1.95, 0.56, 12, 2353, QualityMode.Medium); RiggedMultifractal rigged = new RiggedMultifractal(); Add add = new Add(perlin, rigged); // Initialize the noise map int mapSize = 64; this.m_noiseMap = new Noise2D(mapSize, perlin); //this.m_noiseMap.GeneratePlanar(0, 1, -1, 1); // Generate the textures this.m_noiseMap.GeneratePlanar(-1,1,-1,1); this.m_textures[0] = this.m_noiseMap.GetTexture(this.graphics.GraphicsDevice, Gradient.Grayscale); this.m_noiseMap.GeneratePlanar(mapSize, mapSize * 2, mapSize, mapSize * 2); this.m_textures[1] = this.m_noiseMap.GetTexture(this.graphics.GraphicsDevice, Gradient.Grayscale); this.m_noiseMap.GeneratePlanar(-1, 1, -1, 1); this.m_textures[2] = this.m_noiseMap.GetTexture(this.graphics.GraphicsDevice, Gradient.Grayscale); The first and third ones generate fine, they create a perlin noise map - however the middle one, which I wanted to be a continuation of the first (As per my original post), is just a bunch of static. How exactly do I get this to generate maps that connect to each other, by entering in the mapsize * tile, using the same seed, settings, etc.?

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  • How to get httpd to forward to multiple tomcats for different urls, including / ?

    - by Nick Foote
    Ok So I've got multiple tomcat instances setup on several AJP ports, I also have Apache httpd listening on port 8090 (cos I've got another app already using 8080 at the moment). I've successfully mapped urls such as mydomain.com:8090/demo and mydomain.com:8090/preprod to their respective tomcat instances using Jk Mount and the following vhosts config; <VirtualHost *:8090> JkMount /preprod* preprod JkMount /demo* demo </VirtualHost> But I also want the "root" address to map to another tomcat instance, what will become live/production, ie I want mydomain.com:8090/ to map a 3rd tomcat instance. At the moment nothing happens or changes if I just add to the above config a line; JkMount /* rootwar if I browse to mydomain.com:8090 I just get the same boring apache httpd landing page letting me know its running (ie index.html in httpd/htdocs) Is it possible to use JkMount to redirect the "root" address stuff to a tomcat instance? I can see that a rule like /* will also match URLs like mydomain.com/preprod but I was hoping the rules are applied in order so if /* appears at the end it effectively would be a "if its not one of the other environments, then direct to root/production" Just to be clear I'm trying to setup the following; mydomain.com:8090/preprod --> myApp running in tomcat1 mydomain.com:8090/demo --> myApp running in tomcat2 mydomain.com:8090 --> myApp running in tomcat3

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  • Simplest way to render image over top of another with another image used as mask in OpenGL?

    - by Adam Naylor
    The effect I'm looking for is to have a single large background image that is always visible (at full alpha) and then show a second image (what I call a light map or specular map) that is partially shown over the top based on a third image (which is effectively a mask). The effect is similar to this effect except instead of simply darkening or lightening the background image using the third image it needs to mask the second without effecting the first at all. The third image is the only one that moves therefore hard baking the third images alpha into the second image isn't an option. If my explanation isn't clear I'll provide visual examples when I have more time. I'd prefer not to go down a shader route as I haven't taught myself this area yet so unless I have too I'd rather try to achieve this with simple alpha blending. Happy to use a shader approach. Cheers. Additional These third images are obviously light sources being cast onto the first image showing the specular information from the second image to simulate the light 'shining' off the objects in the first image. The solution I implement will need to allow two light sources to potentially overlap so my current thoughts are that the alpha values of the two images will need to be combined (Added?) to produce a final image which masks the second image? Don't worry about things like coloured lights. For this technique the lights are all considered white.

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  • Application Scope v's Static - Not Quite the same

    - by Duncan Mills
    An interesting question came up today which, innocent as it sounded, needed a second or two to consider. What's the difference between storing say a Map of reference information as a Static as opposed to storing the same map as an application scoped variable in JSF?  From the perspective of the web application itself there seems to be no functional difference, in both cases, the information is confined to the current JVM and potentially visible to your app code (note that Application Scope is not magically propagated across a cluster, you would need a separate instance on each VM). To my mind the primary consideration here is a matter of leakage. A static will be (potentially) visible to everything running within the same VM (OK this depends on which class-loader was used but let's keep this simple), and this includes your model code and indeed other web applications running in the same container. An Application Scoped object, in JSF terms, is much more ring-fenced and is only visible to the Web app itself, not other web apps running on the same server and not directly to the business model layer if that is running in the same VM. So given that I'm a big fan of coding applications to say what I mean, then using Application Scope appeals because it explicitly states how I expect the data to be used and a provides a more explicit statement about visibility and indeed dependency as I'd generally explicitly inject it where it is needed.  Alternative viewpoints / thoughts are, as ever, welcomed...

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  • Graph data structures and journal format for mini-IDE

    - by matec
    Background: I am writing a small/partial IDE. Code is internally converted/parsed into a graph data structure (for fast navigation, syntax-check etc). Functionality to undo/redo (also between sessions) and restoring from crash is implemented by writing to and reading from journal. The journal records modifications to the graph (not to the source). Question: I am hoping for advice on a decision on data-structures and journal format. For the graph I see two possible versions: g-a Graph edges are implemented in the way that one node stores references to other nodes via memory address g-b Every node has an ID. There is an ID-to-memory-address map. Graph uses IDs (instead of addresses) to connect nodes. Moving along an edge from one node to another each time requires lookup in ID-to-address map. And also for the journal: j-a There is a current node (like current working directory in a shell + file-system setting). The journal contains entries like "create new node and connect to current", "connect first child of current node" (relative IDs) j-b Journal uses absolute IDs, e.g. "delete edge 7 - 5", "delete node 5" I could e.g. combine g-a with j-a or combine g-b with j-b. In principle also g-b and j-a should be possible. [My first/original attempt was g-a and a version of j-b that uses addresses, but that turned out to cause severe restrictions: nodes cannot change their addresses (or journal would have to keep track of it), and using journal between two sessions is a mess (or even impossible)] I wonder if variant a or variant b or a combination would be a good idea, what advantages and disadvantages they would have and especially if some variant might be causing troubles later.

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  • Can I delete Generic kernel if I use Generic

    - by user206049
    I currently can't update my release as there is not enough space on boot. I just have the one kernel version there, but seem to have both the Generic and Low Latency versions. uname -r just shows 3.8.0-32-lowlatency ls -lah /boot shows -rw-r--r-- 1 root root 899K Oct 2 00:00 abi-3.8.0-32-generic -rw-r--r-- 1 root root 899K Oct 7 09:27 abi-3.8.0-32-lowlatency -rw-r--r-- 1 root root 152K Oct 2 00:00 config-3.8.0-32-generic -rw-r--r-- 1 root root 152K Oct 7 09:27 config-3.8.0-32-lowlatency drwxr-xr-x 3 root root 2.0K Jan 1 1970 efi drwxr-xr-x 5 root root 1.0K Oct 22 10:05 grub -rw-r--r-- 1 root root 32M Oct 22 09:51 initrd.img-3.8.0-32-generic -rw-r--r-- 1 root root 32M Oct 22 10:05 initrd.img-3.8.0-32-lowlatency drwxr-xr-x 2 root root 12K Feb 25 2013 lost+found -rw-r--r-- 1 root root 173K Dec 5 2012 memtest86+.bin -rw-r--r-- 1 root root 175K Dec 5 2012 memtest86+_multiboot.bin -rw------- 1 root root 3.0M Oct 2 00:00 System.map-3.8.0-32-generic -rw------- 1 root root 3.0M Oct 7 09:27 System.map-3.8.0-32-lowlatency -rw------- 1 root root 5.2M Oct 2 00:00 vmlinuz-3.8.0-32-generic -rw------- 1 root root 5.2M Oct 7 09:27 vmlinuz-3.8.0-32-lowlatency So what can I do to allow me to update? Apparently I need 174m on boot and am 40m short.

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  • A Star Path finding endless loop

    - by PoeHaH
    I have implemented A* algorithm. Sometimes it works, sometimes it doesn't, and it goes through an endless loop. After days of debugging and googling, I hope you can come to the rescue. This is my code: The algorythm: public ArrayList<Coordinate> findClosestPathTo(Coordinate start, Coordinate goal) { ArrayList<Coordinate> closed = new ArrayList<Coordinate>(); ArrayList<Coordinate> open = new ArrayList<Coordinate>(); ArrayList<Coordinate> travelpath = new ArrayList<Coordinate>(); open.add(start); while(open.size()>0) { Coordinate current = searchCoordinateWithLowestF(open); if(current.equals(goal)) { return travelpath; } travelpath.add(current); open.remove(current); closed.add(current); ArrayList<Coordinate> neighbors = current.calculateCoordAdjacencies(true, rowbound, colbound); for(Coordinate n:neighbors) { if(closed.contains(n) || map.isWalkeable(n)) { continue; } int gScore = current.getGvalue() + 1; boolean gScoreIsBest = false; if(!open.contains(n)) { gScoreIsBest = true; n.setHvalue(manhattanHeuristic(n,goal)); open.add(n); } else { if(gScore<n.getGvalue()) { gScoreIsBest = true; } } if(gScoreIsBest) { n.setGvalue(gScore); n.setFvalue(n.getGvalue()+n.getHvalue()); } } } return null; } What I have found out is that it always fails whenever there's an obstacle in the path. If I'm running it on 'open terrain', it seems to work. It seems to be affected by this part: || map.isWalkeable(n) Though, the isWalkeable function seems to work fine. If additional code is needed, I will provide it. Your help is greatly appreciated, Thanks :)

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  • Pathfinding with MicroPather : costs calculations with sectors and portals

    - by Adan
    Hello, I'm considering using micropather to help me with pathfinding. I'm not using a discrete map : I'm working in 2d with sectors and portales. However, I'm just wondering what is the best way to compute costs with this library in this context. Just to be more clear about geometrical shapes I'm using : sectors are basically convex polygons, and portals are segments that lies on sector's edge. Micropather exposes a pure virtual Graph class that you must inherate and overrides 3 functions. I understand how pathfinding works, so there's no problem in overriding those functions. Right now, my implementation give me results, i.e I'm able to find a path in my map, but I'm not sure I'm using an optimal solution. For the AdjacentCost method : I just take the distance between sector's centers as the cost. I think a better solution should be to use the portal between the two sectors, compute its center, and then the cost should be : distance( sector A center, portal center ) + distance ( sector B center, portal center ). I'm pretty sure the approximation I'm using with just sector's center is enough for most cases, but maybe with thin and long sectors that are perpendicular, this approximation could mislead the A* algorithm. For the LeastCostEstimate method : I just take the midpoint of the two sectors. So, as you understand, I'm always working with sectors' centers, and it's working fine. And I'm pretty sure there's a better way to work. Any suggestions or feedbacks? Thanks in advance!

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