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• Designing rules to fight smallpox in Civ-style TBS games

  - by Williham Totland

  TL;DR: How do you design a ruleset for a Civ-style TBS game that prevents city smallpox from being a profitable or viable strategy? Long version: Civ-style games are pretty great. Bringing a civilization from cradle to grave is a great endeavor, and practicing diplomacy with hard-line human players is fun and challenging. In theory. In practice, however, many of these games has, especially in multiplayer, exactly one viable strategy: City smallpox, a.k.a. infinite city spread, a.k.a. covering all available space with 1-citizen cities, packed as tight as they will go. I suppose this could count as emergent gameplay, but still; it could hardly be considered to be in the spirit of the class of game. The Civilization series, of course, is stuck in their more or less fixed rule sets, established with Civilization. Yes, there have been major changes in some respects, but the rules pertaining to city building and maintenance have stayed pretty similar. So the question, then: If you build a ruleset for a TBS from the ground up; what rules should be in place to prevent Infinite City Sprawl from being a viable strategy? Or should ICS be a viable strategy?

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• setPosition of Sprite onUpdate in AndEngine

  - by SSH This

  I am trying to get a "highlighter" circle to follow around a sprite, but I am having trouble, I thought I could use the onUpdate method that's available to me in SequenceEntityModifier but it's not working for me. Here is my code: // make sequence mod with move modifier SequenceEntityModifier modifier = new SequenceEntityModifier(myMovemod) { @Override protected void onModifierFinished(IEntity pItem) { // animation finished super.onModifierFinished(pItem); } public float onUpdate(float pSecondsElapsed, IEntity pItem) { highlighter.setPosition(player2.getX() - highlighterOffset, player2.getY() - highlighterOffset); return pSecondsElapsed; } }; When onUpdate is completely commented out, the sprite moves like I want it to, everything is ok. When I put the onUpdate in, the sprite doesn't move at all. I have a feeling that I am overriding the original onUpdate's actions? Am I going about this the wrong way? I am new to Java, so please feel free to advise if this isn't going to work. UPDATE: The player2 is the sprite that I'm trying to get the highlighter to follow.

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• Best way to implement mouse-based movement in MMOG

  - by fiftyeight

  I want to design an MMO where players click the destination they want to walk to with their mouse and the character moves there, similar to Runescape in this manner. I think it should be easier than keyboard movement since the client can simply send the server the destination each time the player clicks on a destination. The main thing I'm trying to decide is what to do when there are obstacles in the way. It's no problem to implement a simple path-finding solution on the client, the question is if the server will do path-finding as well, since it'll probably take too much Computation power from the server. What I though is that when there is an obstacle the client will send only the first coordinate it plans to go to and then when he gets there he'll send the next coordinate automatically. For example if there is a rock in the way the character will decide on a route that is made of two destinations so it goes around the rock and when it arrives at the first destination it sends the next coordinate. That way if the player changes destination is the middle he won't send unnecessary information. Is this a good way to implement it and is there a standard way MMOGs usually do it? EDIT: I should also mention that the server will make sure all movements are legal and there aren't any walls in the way etc. In the way I wrote it should be quite easy since all movements will be sent in straight lines so the server will just check there aren't any obstacles along that line.

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• How is constant buffer allocation handled in DX11?

  - by Marek

  I'm starting with DX11 and I'm not sure if I'm doing the things right. I want to have both pixel and vertex shader program in one file. Both use some shared and some different constant buffers. So it looks like this: Shader.fx cbuffer ForVS : register(b0) { float4x4 wvp; }; cbuffer ForVSandPS : register(b1) { float4 stuff; float4 stuff2; }; cbuffer ForVS2 : register(b2) { float4 stuff; float4 stuff2; }; cbuffer ForPS : register(b3) { float4 stuff; float4 stuff2; }; .... And in code I use mContext->VSSetConstantBuffers( 0, 1, bufferVS); mContext->VSSetConstantBuffers( 1, 1, bufferVS_PS); mContext->VSSetConstantBuffers( 2, 1, bufferVS2); mContext->PSSetConstantBuffers( 1, 1, bufferVS_PS); mContext->PSSetConstantBuffers( 3, 1, bufferPS); The numbering of buffers in PS is what bugs me, is it alright to bind random slots to shaders (in this example 1 and 3)? Does that mean it still uses just two buffers or does it initialize 0 and 2 buffer pointers to empty? Thank you.

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• Animation Trouble with Java Swing Timer - Also, JFrame Will Not Exit_On_Close

  - by forgotton_semicolon

  So, I am using a Java Swing Timer because putting the animation code in a run() method of a Thread subclass caused an insane amount of flickering that is really a terrible experience for any video game player. Can anyone give me any tips on: Why there is no animation... Why the JFrame will not close when it is coded to Exit_On_Close 2 times My code is here: import java.awt.; import java.awt.event.; import javax.swing.*; import java.net.URL; //////////////////////////////////////////////////////////////// TFQ public class TFQ extends JFrame { DrawingsInSpace dis; //========================================================== constructor public TFQ() { dis = new DrawingsInSpace(); JPanel content = new JPanel(); content.setLayout(new FlowLayout()); this.setContentPane(dis); this.setDefaultCloseOperation(EXIT_ON_CLOSE); this.setTitle("Plasma_Orbs_Off_Orion"); this.setSize(500,500); this.pack(); //... Create timer which calls action listener every second.. // Use full package qualification for javax.swing.Timer // to avoid potential conflicts with java.util.Timer. javax.swing.Timer t = new javax.swing.Timer(500, new TimePhaseListener()); t.start(); } /////////////////////////////////////////////// inner class Listener thing class TimePhaseListener implements ActionListener, KeyListener { // counter int total; // loop control boolean Its_a_go = true; //position of our matrix int tf = -400; //sprite directions int Sprite_Direction; final int RIGHT = 1; final int LEFT = 2; //for obstacle Rectangle mega_obstacle = new Rectangle(200, 0, 20, HEIGHT); public void actionPerformed(ActionEvent e) { //... Whenever this is called, repaint the screen dis.repaint(); addKeyListener(this); while (Its_a_go) { try { dis.repaint(); if(Sprite_Direction == RIGHT) { dis.matrix.x += 2; } // end if i think if(Sprite_Direction == LEFT) { dis.matrix.x -= 2; } } catch(Exception ex) { System.out.println(ex); } } // end while i think } // end actionPerformed @Override public void keyPressed(KeyEvent arg0) { // TODO Auto-generated method stub } @Override public void keyReleased(KeyEvent arg0) { // TODO Auto-generated method stub } @Override public void keyTyped(KeyEvent event) { // TODO Auto-generated method stub if (event.getKeyChar()=='f'){ Sprite_Direction = RIGHT; System.out.println("matrix should be animating now "); System.out.println("current matrix position = " + dis.matrix.x); } if (event.getKeyChar()=='d') { Sprite_Direction = LEFT; System.out.println("matrix should be going in reverse"); System.out.println("current matrix position = " + dis.matrix.x); } } } //================================================================= main public static void main(String[] args) { JFrame SafetyPins = new TFQ(); SafetyPins.setVisible(true); SafetyPins.setSize(500,500); SafetyPins.setResizable(true); SafetyPins.setLocationRelativeTo(null); SafetyPins.setDefaultCloseOperation(EXIT_ON_CLOSE); } } class DrawingsInSpace extends JPanel { URL url1_plasma_orbs; URL url2_matrix; Image img1_plasma_orbs; Image img2_matrix; // for the plasma_orbs Rectangle bbb = new Rectangle(0,0, 0, 0); // for the matrix Rectangle matrix = new Rectangle(-400, 60, 430, 200); public DrawingsInSpace() { //load URLs try { url1_plasma_orbs = this.getClass().getResource("plasma_orbs.png"); url2_matrix = this.getClass().getResource("matrix.png"); } catch(Exception e) { System.out.println(e); } // attach the URLs to the images img1_plasma_orbs = Toolkit.getDefaultToolkit().getImage(url1_plasma_orbs); img2_matrix = Toolkit.getDefaultToolkit().getImage(url2_matrix); } public void paintComponent(Graphics g) { super.paintComponent(g); // draw the plasma_orbs g.drawImage(img1_plasma_orbs, bbb.x, bbb.y,this); //draw the matrix g.drawImage(img2_matrix, matrix.x, matrix.y, this); } } // end class enter code here

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• Generating grammatically correct MUD-style attack descriptions

  - by Extrakun

  I am currently working on a text based game, where the outcome of a combat round goes something like this %attacker% inflicts a serious wound (12 points damage) on %defender% Right now, I just swap %attacker% with the name of the attacker, and %defender% for the name of the defender. However, the description works, but don't read correctly. Since the game is just all text, I don't want to resort to generic descriptions (Such as "You use Attack on Goblin for 5 damage", which arguably solve the problem) How do I generate correct descriptions for cases where %attacker% refers to "You", the player? "You inflicts..." is wrong "Bees", or other plural? I need somehow to know I should prefix the name with a "The " If %attacker% is a generic noun, such as "Goblin", it will read weird as opposed to %attacker% being a name. Compare "Goblin inflicts..." vs. "Aldraic Swordbringer inflicts...." How does text-based games usually resolve such issues?

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• New to CG shader programming, what program should I use to write and test them?

  - by Notbad

  I have started witting some shaders. First ones were fairly easy to write in notepad but now I need something with a bit more meat. I have checked rendermonnkey that seems to support CG but it is really old and don't know if it is a good option. On the other hand there exist this FX Composer 2.0 but it seems somthing that could really distract me from learning shaders because it seems a pretty deep program. Are there any other possibilities? There's a really nice alternative to write shaders named ShaderToy but just supports GLSL. Any information will be really welcomed. Thanks in advance.

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• Blender - creating bones from transform matrices

  - by user975135

  Notice: this is for the Blender 2.5/2.6 API. Back in the old days in the Blender 2.4 API, you could easily create a bone from a transform matrix in your 3d file as EditBones had an attribute named "matrix", which was an armature-space matrix you could access and modify. The new 2.5+ API still has the "matrix" attribute for EditBones, but for some unknown reason it is now read-only. So how to create EditBones from transform matrices? I could only find one thing: a new "transform()" function, which takes a Matrix too. Transform the the bones head, tail, roll and envelope (when the matrix has a scale component). Perfect, but you already need to have some values (loc/rot/scale) for your bone, otherwise transforming with a matrix like this will give you nothing, your bone will be a zero-sized bone which will be deleted by Blender. if you create default bone values first, like this: bone.tail = mathutils.Vector([0,1,0]) Then transform() will work on your bone and it might seem to create correct bones, but setting a tail position actually generates a matrix itself, use transform() and you don't get the matrix from your model file on your EditBone, but the multiplication of your matrix with the bone's existing one. This can be easily proven by comparing the matrices read from the file with EditBone.matrix. Again it might seem correct in Blender, but now export your model and you see your animations are messed up, as the bind pose rotations of the bones are wrong. I've tried to find an alternative way to assign the transformation matrix from my file to my EditBone with no luck.

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• Design patterns for effects between actors and technology

  - by changelog

  I'm working on my first game, and taking the opportunity to brush up my C++ (I want to make as much of it as portable as I can.) Whilst working on the technology tree and how it affects actors (spaceships, planets, crew, buildings, etc) I can't find a pattern that decouples these entities enough to feel like a clean approach. Just as an idea, here's the type of effects these actors can have on one another (and techs too) An engineer inside a spaceship boosts its shield A hero in a spaceship in a fleet increases morale A technology improves spaceships' travel distance A building in a planet improves its production The best I can come up with is the Observer pattern, and basically manage it more or less manually (when a crew member enters a spaceship, fire the event; when a new building is built in a planet, fire the event, etc etc.) but it seems to be too tightly coupled to me. I would love to get some ideas about how to approach this better.

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• Dynamic Quad/Oct Trees

  - by KKlouzal

  I've recently discovered the power of Quadtrees and Octrees and their role in culling/LOD applications, however I've been pondering on the implementations for a Dynamic Quad/Oct Tree. Such tree would not require a complete rebuild when some of the underlying data changes (Vertex Data). Would it be possible to create such a tree? What would that look like? Could someone point me in the correct direction to get started? The application here would, in my scenario, be used for a dynamically changing spherical landscape with over 10,000,000 verticies. The use of Quad/Oct Trees is obvious for Culling & LOD as well as the benefits from not having to completely recompute the tree when the underlying data changes.

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• Checking whether a specific key was pressed in enchantJS

  - by MxyL

  I am using enchantJS and would like to use the letters and numbers as well as numpad on a keyboard to do different things (eg: hotkeys). From this page http://users.csc.calpoly.edu/~foaad/enchant/guide/playerInput.html By default, enchant.js provides input listeners for six buttons: UP, DOWN, LEFT, RIGHT, A, and B. By default, the directions are bound to the arrow keys. Any of the six buttons may also be bound to any key with an ASCII value. We’ll address that later. So enchant provides the ability to bind keys to different input such as up, down, left, right...but how can I simply check whether the D or X key was pressed, and if so, perform certain actions based on that event?

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• Rotate 3D Model from a custom position

  - by Nipuna Silva

  I have a 3D Model like above in which i want to rotate it from a given location(pointed in red) but I can only rotate it from the middle. How can I rotate it from a custom point. Edit: I successfully able to rotate the model from the below position by getting the radius of the model and applying it to the world matrix Vector3 point = new Vector3(-radius, 0, 0); world = Matrix.CreateTranslation(-radius, 0, 0); But now I cannot change the position of the object and it always centered in middle of the screen. I think that's because i applied the above code. How can I place it anywhere I want?

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• How do I dynamically reload content files?

  - by Kikaimaru

  Is there a relatively simple way to dynamically reload content files, such as effect files? I know I can do the following: Detect change of file Run content pipeline to rebuild that specific file Unload ALL content that was loaded Load all content And use double references to reference content files. The problem is with step 3 (and step 2 isn't that nice either). I need to unload everything because if I have model Hero.x which references Model.fx effect, and I change the Model.fx file, I need to reload the Hero.x file which will then call LoadExternalReference on Model.fx. Has someone managed to make this work without rewriting the whole ContentManager (and every ContentReader) and tracking calls to LoadExternalReference?

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• OnTrigger not firing consistently

  - by Lautaro

  I have a Prefab called Player which has a Body and a Sword. The game uses 2 instances of Player, Player1 and Player2. I use Player1 to strike Player2. This is code on the sword. My hope is that Sword of Player1 will log on contct with Body of Player2. It happens but only the first hit and then i have to hit several times before another strike is logged. But when i look at log from OnTriggerStay it looks like the TriggerExit is never detected untill long after the sword is gone. void OnTriggerEnter(Collider other) { //Play sound to confirm collision var sm = ObjectDirectory.soundManager; sm.PlaySoundClip(sm.gui_02); Debug.Log(other.name + " - ENTER" ); } void OnTriggerStay(Collider other) { Debug.Log(other.name + " - collision" ); } void OnTriggerExit(Collider other) { Debug.Log(other.name + " - HAS LEFT" ); } DEBUG LOG: Player2 - ENTER UnityEngine.Debug:Log(Object) SwordControl:OnTriggerEnter(Collider) (at Assets/Scripts/SwordControl.cs:28) Player2 - collision UnityEngine.Debug:Log(Object) SwordControl:OnTriggerStay(Collider) (at Assets/Scripts/SwordControl.cs:34) (The last debug log then repeated hundreds of times long after the sword of player 1 had withdrawn and was in no contact with player 2 ) EDIT: Further tests shows that if i move player1 backwards away form player2 i trigger the OnTriggerExit. Even if the sword is not touching Player2 since after the blow. However even after OnTriggerExit it takes many tries untill i can get another blow registered.

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• Low complexity shader to indicate the sides of a polyline

  - by Pris

  I have a bunch of polylines that I draw using GL_LINES. They can have thousands of points. They actually represent the separation of land and water on a map. I don't have complete polygons, just the ordered set of points. I'm looking for a neat but efficient way to visually convey Side A and Side B as being different. For example I could offset the polyline in one direction a few times and fade it out (but every offset is doubling the number of points), or offset it once to make a "ribbon" and give one side a 'glow' like effect to mimic the outer glow or shadow of a polygon). This is for a mobile application and I'm using OpenGL ES 2. I'd like to keep the effect as simple as possible from a complexity stand point. I'm looking for some additional ideas; maybe there's a clever shader technique out there or a visual effect I haven't considered.

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• xbox thumbstick used to rotate sprite, basic formula makes it "stick" or feel "sticky" at 90 degree intervals! how do get smooth rotation?

  - by Hugh

  Context: C#, XNA game I am using a very basic formula to calculate what angle my sprite (spaceship for example) should be facing based on the xbox controller thumbstick ie. you use the thumbstick to rotate the ship! in my main update method: shuttleAngle = (float) Math.Atan2(newGamePadState.ThumbSticks.Right.X, newGamePadState.ThumbSticks.Right.Y); in my main draw method: spriteBatch.Draw(shuttle, shuttleCoords, sourceRectangle, Color.White, shuttleAngle, origin, 1.0f, SpriteEffects.None, 1); as you can see its quite simple, i take the current radians from the thumbstick and store it in a float "shuttleAngle" and then use this as the rotation angle (in radians) arguement for drawing the shuttle. For some reason when i rotate the sprint it feels sticky at 0, 90, 180 and 270 degrees angles, it wants to settle at those angles. its not giving me a smooth and natural rotation like i would feel in a game that uses a similar mechanic. PS: my xbox controller is fine!

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• XNA frame rate spikes in full screen mode

  - by ProgrammerAtWork

  I'm loading a simple texture and rotating it in XNA, and this works. But when I run it in full screen 1920x1080 mode I see spikes while my texture is rotating. If I run it windowed with 1920x1080 resolution, I don't get the spikes. The size of the texture does not seem to matter, I tried 512 texture size and 2048 texture size, same thing happens. Spikes in full screen, no spikes in windowed, resolution does not seem to matter, Debug or Release does not seem to do anything either. Anyone got ideas of what could be the problem? Edit: I think this problem has something to do with the vertical retrace. Set this property: _graphicsDeviceManager.SynchronizeWithVerticalRetrace = false; you'll lose vsync but it will not stutter.

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• How do you pack resources in a game when you have too many of them?

  - by ThePlan

  I've recently made a basic space invaders clone in C++ using the Allegro 5 framework. It took me a long time, but after I finished, I realized I had about 10 sprites, and 13MB worth of DLLs (Some of the people didn't even have the mingW dlls) which were making people who played the game very confused. How can I "pack" all my resources in a way that I can easily add-remove data to my game, and to reduce the size taken by the resource, basically placing them in 1 spot? I'm using codeblocks.

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• Complete Guide/Tutorials on LWJGL?

  - by user43353

  Dont get me wrong, I finished these tutorials on http://lwjgl.org/wiki/index.php?title=Main_Page. I finished The Basics section, OpenGL 3.2 and newer section, and I looked at the Example Code section. They were great tutorials, and I have looked at the external tutorials as well. I don't know where to go from here, and OpenGL is not my strong point. Some one suggested Learning Modern 3D Graphics Programming, and I didnt learn much. I looked at the port to LWJGL, but the book was on C and I couldn't really understand what the OpenGL meant. I am trying to learn 2D gaming, not 3D. Maybe later. Is there any tutorials that aren't C/C++ heavy and teach you 2D OpenGL?

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• libgdx arrays onTouch() method and delays for objects

  - by johnny-b

  i am trying to create random bullets but it is not working for some reason. also how can i make a delay so the bullets come every 30 seconds or 1 minute???? also the onTouch method does not work and it is not taking the bullet away???? shall i put the array in the GameRender class? thanks public class GameWorld { public static Ball ball; private Bullet bullet1; private ScrollHandler scroller; private Array<Bullet> bullets = new Array<Bullet>(); public GameWorld() { ball = new Ball(280, 273, 32, 32); bullet = new Bullet(-300, 200); scroller = new ScrollHandler(0); bullets.add(new Bullet(bullet.getX(), bullet.getY())); bullets = new Array<Bullet>(); Bullet bullet = null; float bulletX = 0.0f; float bulletY = 0.0f; for (int i=0; i < 10; i++) { bulletX = MathUtils.random(-10, 10); bulletY = MathUtils.random(-10, 10); bullet = new Bullet(bulletX, bulletY); bullets.add(bullet); } } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet1() { return bullet1; } } i also tried this and it is not working, i used this in the GameRender class Array<Bullet> enemies=new Array<Bullet>(); //in the constructor of the class enemies.add(new Bullet(bullet.getX(), bullet.getY())); // this throws an exception for some reason??? this is in the render method for(int i=0; i<bullet.size; i++) bullet.get(i).draw(batcher); //this i am using in any method that will allow me from the constructor to update to render for(int i=0; i<bullet.size; i++) bullet.get(i).update(delta); this is not taking the bullet out @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { for(int i=0; i<bullet.size; i++) if(bullet.get(i).getBounds().contains(screenX,screenY)) bullet.removeIndex(i--); return false; } thanks for the help anyone.

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• Why am I getting a return value of zero from my position computation function?

  - by Hussain Murtaza

  Ok I have a Function int x(), which is used in new Rectangle(x(),a,a,a); in DrawMethod in XNA but when I use it I get x() = 0 as as the answer.Here is my CODE: int x() { int px = (128 * 5); int xx = 0; for (int i = 0; i < 6; i++) { if (Mouse.GetState().X > px) { //xx = Mouse.GetState().X; xx = px; break; } else { px -= 128; } } return xx; } Here is the DrawMethod Code: if (set) { spriteBatch.Draw(texture, new Rectangle(x(), y(), texture.Width, texture.Height), Color.White); textpositionX = x(); textpositionY = y(); set = false; select = false; place = true; } else if(select) { spriteBatch.Draw(texture, new Rectangle(Mouse.GetState().X - texture.Width / 2, Mouse.GetState().Y-texture.Height / 2, texture.Width, texture.Height), Color.White); } else if (place) { spriteBatch.Draw(texture, new Rectangle(textpositionX, textpositionY, texture.Width, texture.Height), Color.White); select = false; set = false; }

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• Save programmatically created Mesh to .X Files using SlimDX throw null exception

  - by zionpi

  Mesh has been created properly using SlimDX,but when I use the following line: Mesh.ToXFile(barMesh, "foo.x", XFileFormat.Text,CharSet.Unicode); It throws NullReferenceException,through monitor window I can see barMesh is not null, inside the mesh structrue, SkinInfo is null. If SkinInfo is the problem,then how can I initialize it properly?Internet doesn't seems have much information on this.

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• Looking for a small, light scene graph style abstraction lib for shader based OpenGL

  - by Pris

  I'm looking for a 'lean and mean' c/c++ scene graph library for OpenGL that doesn't use any deprecated functionality. It should be cross platform (strictly speaking I just dev on Linux so no love lost if it doesn't work on Windows), and it should be possible to deploy to mobile targets (ie OpenGLES2, and no crazy mandatory dependencies that wouldn't port well to modern mobile frameworks like iOS, Android, etc), with a license that's compatible with closed source software (LGPL or more liberal). Specific nice-to-haves would be: Cameras and Viewers (trackball, fly-by, etc) Object transform hierarchies (if B is a child of A, and you move A, B has the same transform applied to it) Simple animation Scene optimization (frustum culling, use VBOs, minimize state changes, etc) Text I've played around with OpenSceneGraph a lot and it's pretty amazing for fixed function pipeline stuff, but I've had a few of problems using it with the programmable pipeline and after going through their mailing list, it seems several people have had similar issues (going back years). Kitware's VES looks neat (http://www.vtk.org/Wiki/VES), but VES + VTK is pretty heavy. VTK is also typically for analyzing scientific data and I've read that it's not that appropriate for a general use case (not that great at rendering a lot of objects on scene,etc) I'm currently looking at VisualizationLibrary (http://www.visualizationlibrary.org/documentation/pag_gallery.html) which looks like it offers some of the functionality I'd like, but it doesn't explicitly support mobile targets. Other solutions like Ogre, Horde3D, Irrlicht, etc tend to be full on game engines and that's not really what I'm looking for. I'd like some suggestions for other libraries that I may have missed... please note I'm not willing to roll my own solution from scratch.

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• Question about BoundingSpheres and Ray intersections

  - by NDraskovic

  I'm working on a XNA project (not really a game) and I'm having some trouble with picking algorithm. I have a few types of 3D models that I draw to the screen, and one of them is a switch. So I'm trying to make a picking algorithm that would enable the user to click on the switch and that would trigger some other function. The problem is that the BoundingSphere.Intersect() method always returns null as result. This is the code I'm using: In the declaration section: ` //Basic matrices private Matrix world = Matrix.CreateTranslation(new Vector3(0, 0, 0)); private Matrix view = Matrix.CreateLookAt(new Vector3(10, 10, 10), new Vector3(0, 0, 0), Vector3.UnitY); private Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45), 800f / 600f, 0.01f, 100f); //Collision detection variables Viewport mainViewport; List<BoundingSphere> spheres = new List<BoundingSphere>(); Ray ControlRay; Vector3 nearPoint, farPoint, nearPlane, farPlane, direction; ` And then in the Update method: ` nearPlane = new Vector3((float)Mouse.GetState().X, (float)Mouse.GetState().Y, 0.0f); farPlane = new Vector3((float)Mouse.GetState().X, (float)Mouse.GetState().Y, 10.0f); nearPoint = GraphicsDevice.Viewport.Unproject(nearPlane, projection, view, world); farPoint = GraphicsDevice.Viewport.Unproject(farPlane, projection, view, world); direction = farPoint - nearPoint; direction.Normalize(); ControlRay = new Ray(nearPoint, direction); if (spheres.Count != 0) { for (int i = 0; i < spheres.Count; i++) { if (spheres[i].Intersects(ControlRay) != null) { Window.Title = spheres[i].Center.ToString(); } else { Window.Title = "Empty"; } } ` The "spheres" list gets filled when the 3D object data gets loaded (I read it from a .txt file). For every object marked as switch (I use simple numbers to determine which object is to be drawn), a BoundingSphere is created (center is on the coordinates of the 3D object, and the diameter is always the same), and added to the list. The objects are drawn normally (and spheres.Count is not 0), I can see them on the screen, but the Window title always says "Empty" (of course this is just for testing purposes, I will add the real function when I get positive results) meaning that there is no intersection between the ControlRay and any of the bounding spheres. I think that my basic matrices (world, view and projection) are making some problems, but I cant figure out what. Please help.

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• Annoying flickering of vertices and edges (possible z-fighting)

  - by Belgin

  I'm trying to make a software z-buffer implementation, however, after I generate the z-buffer and proceed with the vertex culling, I get pretty severe discrepancies between the vertex depth and the depth of the buffer at their projected coordinates on the screen (i.e. zbuffer[v.xp][v.yp] != v.z, where xp and yp are the projected x and y coordinates of the vertex v), sometimes by a small fraction of a unit and sometimes by 2 or 3 units. Here's what I think is happening: Each triangle's data structure holds the plane's (that is defined by the triangle) coefficients (a, b, c, d) computed from its three vertices from their normal: void computeNormal(Vertex *v1, Vertex *v2, Vertex *v3, double *a, double *b, double *c) { double a1 = v1 -> x - v2 -> x; double a2 = v1 -> y - v2 -> y; double a3 = v1 -> z - v2 -> z; double b1 = v3 -> x - v2 -> x; double b2 = v3 -> y - v2 -> y; double b3 = v3 -> z - v2 -> z; *a = a2*b3 - a3*b2; *b = -(a1*b3 - a3*b1); *c = a1*b2 - a2*b1; } void computePlane(Poly *p) { double x = p -> verts[0] -> x; double y = p -> verts[0] -> y; double z = p -> verts[0] -> z; computeNormal(p -> verts[0], p -> verts[1], p -> verts[2], &p -> a, &p -> b, &p -> c); p -> d = p -> a * x + p -> b * y + p -> c * z; } The z-buffer just holds the smallest depth at the respective xy coordinate by somewhat casting rays to the polygon (I haven't quite got interpolation right yet so I'm using this slower method until I do) and determining the z coordinate from the reversed perspective projection formulas (which I got from here: double z = -(b*Ez*y + a*Ez*x - d*Ez)/(b*y + a*x + c*Ez - b*Ey - a*Ex); Where x and y are the pixel's coordinates on the screen; a, b, c, and d are the planes coefficients; Ex, Ey, and Ez are the eye's (camera's) coordinates. This last formula does not accurately give the exact vertices' z coordinate at their projected x and y coordinates on the screen, probably because of some floating point inaccuracy (i.e. I've seen it return something like 3.001 when the vertex's z-coordinate was actually 2.998). Here is the portion of code that hides the vertices that shouldn't be visible: for(i = 0; i < shape.nverts; ++i) { double dist = shape.verts[i].z; if(z_buffer[shape.verts[i].yp][shape.verts[i].xp].z < dist) shape.verts[i].visible = 0; else shape.verts[i].visible = 1; } How do I solve this issue? EDIT I've implemented the near and far planes of the frustum, with 24 bit accuracy, and now I have some questions: Is this what I have to do this in order to resolve the flickering? When I compare the z value of the vertex with the z value in the buffer, do I have to convert the z value of the vertex to z' using the formula, or do I convert the value in the buffer back to the original z, and how do I do that? What are some decent values for near and far? Thanks in advance.

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