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• SFML title bar with weird characters when using UTF-8

  - by TheOm3ga

  (Previously asked at http://stackoverflow.com/questions/4922478/sfml-title-bar-with-weird-characters-when-using-utf-8) I've just started using SFML and one of the first problems I've come across is some weird characters on the the titlebar whenever I try to use accents or any other extended char. For instance, I've got: sf::RenderWindow Ventana(sf::VideoMode(800, 600, 32), "Año nuevóóó"); And the titlebar renders like AÂ+o nuevoA³A³A³ This ONLY HAPPENS if my source code file is enconded in UTF-8. If I change the file encoding to ISO-8859-1, it shows properly. Obviously all of my files use UTF-8, as its the system-wide encoding. I'm using GCC under Ubuntu GNU/Linux. I've tried using the different utilities in sf::Unicode to adapt the text, but none of them seems to work.

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• What is the best type of c# timer to use with a Unity game that uses many timers simultaneously?

  - by Kyle Seidlitz

  I am developing a stand-alone 3d game in Unity that will have anywhere from 1 to 200 timers running simultaneously. There will be a GameObject containing 1 timer. For this game timer durations will range from 5 minutes to 4 days. There will not be any countdown displays or any UI for the timers. Each object is a prefab, with all the necessary materials included. An attached script will handle the timer and all the necessary code to change the materials and make any sound effects. Once the timer is expired, the user will then click on the object again, and the object will be destroyed, and the user's inventory will be adjusted. If the user wants to save or end the game before all the timers are done, the start value of the still running timers is to be saved to an XML file such that when the game is started again, any still running timers will be checked to see if they have expired, where the object's materials will be changed appropriately. I am still trying to figure out what type of timer to use, and see also if there are any suggestions for saving and calculating times over several days. What class(es) of timers should I use? Are there any special issues I should look out for in terms of performance?

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• OpenGL lighting with dynamic geometry

  - by Tank

  I'm currently thinking hard about how to implement lighting in my game. The geometry is quite dynamic (fixed 3D grid with custom geometry in each cell) and needs some light to get more depth and in general look nicer. A scene in my game always contains sunlight and local light sources like lamps (point lights). One can move underground, so sunlight must be able to illuminate as far as it can get. Here's a render of a typical situation: The lamp is positioned behind the wall to the top, and in the hollow cube there's a hole in the back, so that light can shine through. (I don't want soft shadows, this is just for illustration) While spending the whole day searching through Google, I stumbled on some keywords like deferred rendering, forward rendering, ambient occlusion, screen space ambient occlusion etc. Some articles/tutorials even refer to "normal shading", but to be honest I don't really have an idea to even do simple shading. OpenGL of course has a fixed lighting pipeline with 8 possible light sources. However they just illuminate all vertices without checking for occluding geometry. I'd be very thankful if someone could give me some pointers into the right direction. I don't need complete solutions or similar, just good sources with information understandable for someone with nearly no lighting experience (preferably with OpenGL).

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• Jitter during wall collisions with Bullet Physics: contact/penetration tolerance?

  - by Niriel

  I use the bullet physics engine through Panda3d. My scene is still very simple, think 'Wolfenstein3d': tile-based, walls are solid cubes. I expect walls to block the player, and I expect the player to slide along the walls in case of non-normal incidence. What I get is what I expect, with one difference: there is some jitter. If I try to force myself into the wall, then I see the frames blinking quickly between two positions. These differ by about 0.04 units of distance, which corresponds to 4 cm in my game. I noticed a 4 cm elsewhere: the bottom of my player capsule is 4 cm below ground, when at rest. Does that mean that there is somewhere in the Bullet engine a default 0.04-units-long tolerance to differentiate contact from collision? If so, what should I do ? Should I change the scale of my game so that these 0.04 units correspond to 0.4 cm, making the jitter ten times smaller? Or can I ask bullet to change its tolerance to a smaller value? Edit This is the jitter I get: 6.155 - 6.118 = 0.036 LPoint3f(0, 6.11694, 0.835) LPoint3f(0, 6.15499, 0.835) LPoint3f(0, 6.11802, 0.835) LPoint3f(0, 6.15545, 0.835) LPoint3f(0, 6.11817, 0.835) LPoint3f(0, 6.15726, 0.835) LPoint3f(0, 6.11876, 0.835) LPoint3f(0, 6.15911, 0.835) LPoint3f(0, 6.11937, 0.835) I found a setMargin method. I set it to 5 mm both on the BoxShape for the walls and on the Capsule shape for the player. It still jitters by about 35 mm as illustrated by this log (11.117 - 11.082 = 0.035): LPoint3f(0, 11.0821, 0.905) LPoint3f(0, 11.1169, 0.905) LPoint3f(0, 11.082, 0.905) LPoint3f(0, 11.117, 0.905) LPoint3f(0, 11.082, 0.905) LPoint3f(0, 11.117, 0.905) LPoint3f(0, 11.0821, 0.905) LPoint3f(0, 11.1175, 0.905) LPoint3f(0, 11.0822, 0.905) LPoint3f(0, 11.1178, 0.905) LPoint3f(0, 11.0823, 0.905) LPoint3f(0, 11.1183, 0.905) The margin on the capsule did change my penetration with the floor though, I'm a bit higher (0.905 instead of 0.835). However, it did not change anything when colliding with the walls. How can I make the collisions against the walls less jittery? Edit, the day after: After more investigation, it appears that dynamic objects behave well. My problem comes from the btKinematicCharacterController that I use for moving my character; that stuff is totally bugged, according to the whole Internet :/.

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• Switching songs - MediaPlayer lags the game

  - by Fibericon

  When the player encounters a boss in the game I'm working on, I want to have the music change. It seems simple enough with the MediaPlayer class to fade out the current song, switch to another, and then fade the new song in. However, at the point where the second song starts, the game freezes for a split second. The songs in question aren't particularly large either - the first song is 1.7mb and the second song is 3.1mb, both mp3 format. This is the code I'm using to do it: protected void switchSong(GameTime gameTime) { if (!bossSongPlaying) { MediaPlayer.Volume -= ((float)gameTime.ElapsedGameTime.TotalSeconds/10); if (MediaPlayer.Volume < 0.05f) { MediaPlayer.Play(bossSong); MediaPlayer.Volume = 1.0f; bossSongPlaying = true; } } } What can I do to eliminate that momentary hang?

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• How can I make permanent death in a MUD seem acceptable and fair to players?

  - by Luke Laupheimer

  I have considered writing a MUD for years, and I have a lot of ideas my friends think are really cool (and that's how I'd hope to get anywhere -- word of mouth). Thing is, there's one thing I have always wanted, that my friends and strangers hated: permanent death. Now, the emotional response I get to this is visceral revulsion, every time. I'm pretty sure I am the only person that wants this, or if I'm not, I'm a tiny minority. Now, the reason I want it is because I want the actions of the players to matter. Unlike a lot of other MUDs, which have a set of static city-states and social institutions etc, I want the things my players do, should I get any, to actually change the situation. And that includes killing people. If you kill someone, you didn't send them to time out, you killed them. What happens when you kill people? They go away. They don't come back in half an hour to smack talk you some more. They're gone. Forever. By making death non-permanent, you make death not matter. It would be similar if a climax to a character's arc is getting a speeding ticket. It cheapens it. Non-permanent death cheapens death. How can I: 1) Convince my players (and random people!) that this is actually a good idea?, or 2) Find some other way to make death and violence matter as much as it does in real life (except within the game, of course) sans character deletion? What alternatives are there out there?

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• Disable printing extraneous job info when I print a images

  - by pgrytdal

  As of 10/11/12 I this is still a problem. Peterling, that link you gave me was for Windows. Not Ubuntu. I need to know how to do this in Ubuntu. Whenever I print off an image, before the actual image prints, I get these weird "print job" sheets. (I named them that, because I don't know what else to call them.) They say something like: Media Limits: 0.12 x 0.38 to 8.38 x 10.38 inches Job ID: Officejet-Pro-L7700-64 Driver: hp-officejet_pro_17700.ppd Driver version: Description: HP Officejet Pro L7700 Make and Model: HP Officejet Pro L7700, hpcups 3.12.2 Printer: Officejet-Pro-L7700 Created at: Fri Sep 28 14:12:53 2012 Printed at: Fri Sep 28 14:12:53 2012 How do I fix this so the page doesn't print?

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• object detection in bitmmap javacanvas

  - by user1538127

  i want to detect clicks on canvas elements which are drawn using paths. so far i have think of to store elements path in javascript data structure and then check the cordinates of hits which matches the elements cordinates. i belive there is algorithm already for thins kind o cordinate search. rendering each of element path and checking the hits would be inefficient when elements number is larger. can anyone point on me that?

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• How do I create a bounding frustrum from a view & projection matrix?

  - by Narf the Mouse

  Given a left-handed Projection matrix, a left-handed View matrix, a ViewProj matrix of View * Projection - How do I create a bounding Frustum comprised of near, far, left, right and top, bottom planes? The only example I could find on Google (Tutorial 16: Frustum Culling) seems to not work; for example, if the math is used as given, the near-plane's distance is a negative. This places the near-plane behind the camera...

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• Entity system in Lua, communication with C++ and level editor. Need advice.

  - by Notbad

  Hi!, I know this is a really difficult subject. I have been reading a lot this days about Entity systems, etc... And now I'm ready to ask some questions (if you don't mind answering them) because I'm really messed. First of all, I have a 2D basic editor written in Qt, and I'm in the process of adding entitiy edition. I want the editor to be able to receive RTTI information from entities to change properties, create some logic being able to link published events to published actions (Ex:A level activate event throws a door open action), etc... Because all of this I guess my entity system should be written in scripting, in my case Lua. In the other hand I want to use a component based design for my entities, and here starts my questions: 1) Should I define my componentes en C++? If I do this en C++ won't I loose all the RTTI information I want for my editor?. In the other hand, I use box2d for physics, if I define all my components in script won't it be a lot of work to expose third party libs to lua? 2) Where should I place the messa system for my game engine? Lua? C++?. I'm tempted to just have C++ object to behave as servers, offering services to lua business logic. Things like physics system, rendering system, input system, World class, etc... And for all the other things, lua. Creation/Composition of entities based on components, game logic, etc... Could anyone give any insight on how to accomplish this? And what aproach is better?. Thanks in advance, HexDump.

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• how to modify shadow mapping in "3D Graphics with XNA Game Studio 4.0"?

  - by naprox

  So I've been following the tutorials from the book Sean James's "3D Graphics with XNA Game Studio 4.0", and have been doing fine until i reached the shadow mapping part. in this book it creates point lights with a Sphere model. my first Q is how to draw a directional Light with this frame work? secondly it can do shadow mapping just for one light, how can i do shadow mapping for all or parts of the lights in the game? i just want to know how to modify this codes to do the above tasks. I've followed tutorials on MSDN and some other sites and didn't got the answer. please help me, its so urgent. and if any one wants, the complete code is here: http://www.mediafire.com/?6ct11mc1g8f891h

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• Well-tested libraries for player ratings?

  - by Lucky

  It's common in games to implement some sort of numerical ranking system -- the ELO system is usually used in chess. I could implement this system naively using Wikipedia's descriptions, but I suspect that this would open up a whole box of problems that have already been solved: rating inflation, etc -- for instance, the ELO system has a K constant that's 'fudged' according to rating, duration, pairings, statistics, ... What are some libraries (I'm looking at Python, but anything is okay) that implements rating systems? It also doesn't have to be ELO.

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• XNA ModelMesh.Draw vs GraphicsDevice.DrawIndexedPrimitives

  - by cubrman

  I am using XNA 4.0 and I wonder if drawing models with multiple meshes is better by filling the vertex and index buffers first and calling GraphicsDevice.DrawIndexedPrimitives() or by simply using good ol' foreach(...) {ModelMesh.Draw()}. Is it possible to add data to vertex/index buffers at all in order to pack all the models on the scene in them and then call Draw only once per frame? I would appreciate a link to an in-depth explanation. Thanks.

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• How can I support the creation and rendering of both interior and exterior environments?

  - by Nick

  Say I already have a renderer that can support outdoor terrain and environment rendering. How would I go about adding support for interior environments (for example, like World of Warcraft's dungeons) to my game? I'm interested both in how I should fit the interiors into my content creation process (for example, I thought about leaving holes in the terrain mesh into which I can "paste" the interior dungeon mesh at runtime) and how to render them (it seems like I'd want a different rendering flow other than a blended texture rendering phase that terrain uses).

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• Point Light Soft Shadows

  - by notabene

  How to implement soft shadows for omni directional (point) light. We use typical shadow mapping technique. Depth is rendered to texture cube and addresing is pretty simple then. Just using vector from light to fragments world position. It works perfectly. Until you want soft shadows. In our engine we use PCSS technique for spot lights. But for point light there begins troubles. How to sample in 3D? I developed technique when orthonormal basis is created from a direction and upvector (0,1,0). And then multiply sampling vector (something like this (1.0,i/depthMapSize,j/depthMapSize) with this basis. But this (of course :)) looks pretty bad for vectors near (0,1,0) and (0,-1,0). I will appreciate any help on this.

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• With Slick, how to change the resolution during gameplay?

  - by TheLima

  I am developing a tile-based strategy game using Java and the Slick API. So far so good, but I've come to a standstill on my options menu. I have plans for the user to be able to change the resolution during gameplay (it is pretty common, after all). I can already change to fullscreen and back to windowed, this was pretty simple... //"fullScreenOption" is a checkbox-like button. if (fullScreenOption.isMouseOver(mouseX, mouseY)) { if (input.isMouseButtonDown(Input.MOUSE_LEFT_BUTTON)) { fullScreenOption.state = !fullScreenOption.state; container.setFullscreen(fullScreenOption.state); } } But the container class (Implemented by Slick, not me), contrary to my previous beliefs, does not seem to have any resolution-change functions! And that's pretty much the situation...I know it's possible, but i don't know how to do it, nor what is the class responsible! The AppGameContainer class, used on the very start of the game's initialization, is the only place with any functions for changing the display-mode that I've found so far, but it's only used at the very start, and i haven't found a way to travel back to it from my options menu. //This is my implementation of it... public static void main(String[] args) throws SlickException { AppGameContainer app = new AppGameContainer(new Main()); // app.setTargetFrameRate(60); app.setVSync(true); app.setDisplayMode(800, 600, false); app.start(); } I can define it as a static global on the Main, but it's probably a (very) bad way to do it...

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• Initial direction of intersection between two moving vehicles?

  - by Larolaro

  I'm working with a bit of projectile prediction for my AI and I'm looking for some ideas, any input? If a blue vehicle is moving in a direction at a constant speed of X m/s and a stationary orange vehicle has a rocket that travels Y m/s, which initial direction would the orange vehicle have to fire the rocket for it to hit the blue vehicle at the earliest time in the future? Thanks for reading!

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• How do I implement Unreal-like object serialization?

  - by MrWiggels

  Recently, I've been working on the core of my engine, and as I'm moving forward I find myself developing throwaway code to read files and simple data into the engine. This got me thinking about how I should implement a file management system. After a bit of googleing I came across the Unreal Package format, and boy does it look like the perfect one. I think it's good because the way how it allows you to separate different assets into different packages and allow something like a level to reference the different packages. I was just wondering, is this possible with C#? Because the built-in serialization API in .NET does not seem to support any form of this, only reading and writing to a single file.

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• 2D Particle Explosion

  - by TheBroodian

  I'm developing a 2D action game, and in said game I've given my primary character an ability he can use to throw a fireball. I'm trying to design an effect so that when said fireball collides (be it with terrain or with an enemy) that the fireball will explode. For the explosion effect I've created a particle that once placed into game space will follow random, yet autonomic behavior based on random variables. Here is my question: When I generate my explosion (essentially 90 of these particles) I get one of two behaviors, 1) They are all generated with the same random variables, and don't resemble an explosion at all, more like a large mass of clumped sprites that all follow the same randomly generated path. 2) If I assign each particle a unique seed to its random number generator, they are a little bit -more- spread out, yet clumping is still visible (they seem to fork out into 3 different directions) Does anybody have any tips for producing particle-based 2D explosions? I'll include the code for my particle and the event I'm generating them in. Fire particle class: public FireParticle(xTile.Dimensions.Location StartLocation, ContentManager content) { worldLocation = StartLocation; fireParticleAnimation = new FireParticleAnimation(content); random = new Random(); int rightorleft = random.Next(0, 3); int upordown = random.Next(1, 3); int xVelocity = random.Next(0, 101); int yVelocity = random.Next(0, 101); Vector2 tempVector2 = new Vector2(0,0); if (rightorleft == 1) { tempVector2 = new Vector2(xVelocity, tempVector2.Y); } else if (rightorleft == 2) { tempVector2 = new Vector2(-xVelocity, tempVector2.Y); } if (upordown == 1) { tempVector2 = new Vector2(tempVector2.X, -yVelocity); } else if (upordown == 2) { tempVector2 = new Vector2(tempVector2.X, yVelocity); } velocity = tempVector2; scale = random.Next(1, 11); upwardForce = -10; dead = false; } public FireParticle(xTile.Dimensions.Location StartLocation, ContentManager content, int seed) { worldLocation = StartLocation; fireParticleAnimation = new FireParticleAnimation(content); random = new Random(seed); int rightorleft = random.Next(0, 3); int upordown = random.Next(1, 3); int xVelocity = random.Next(0, 101); int yVelocity = random.Next(0, 101); Vector2 tempVector2 = new Vector2(0, 0); if (rightorleft == 1) { tempVector2 = new Vector2(xVelocity, tempVector2.Y); } else if (rightorleft == 2) { tempVector2 = new Vector2(-xVelocity, tempVector2.Y); } if (upordown == 1) { tempVector2 = new Vector2(tempVector2.X, -yVelocity); } else if (upordown == 2) { tempVector2 = new Vector2(tempVector2.X, yVelocity); } velocity = tempVector2; scale = random.Next(1, 11); upwardForce = -10; dead = false; } #endregion #region Update and Draw public void Update(GameTime gameTime) { elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; fireParticleAnimation.Update(gameTime); Vector2 moveAmount = velocity * elapsed; xTile.Dimensions.Location newPosition = new xTile.Dimensions.Location(worldLocation.X + (int)moveAmount.X, worldLocation.Y + (int)moveAmount.Y); worldLocation = newPosition; velocity.Y += upwardForce; if (fireParticleAnimation.finishedPlaying) { dead = true; } } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw( fireParticleAnimation.image.Image, new Rectangle((int)drawLocation.X, (int)drawLocation.Y, scale, scale), fireParticleAnimation.image.SizeAndsource, Color.White * fireParticleAnimation.image.Alpha); } Fireball explosion event: public override void Update(GameTime gameTime) { if (enabled) { float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; foreach (Heart_of_Fire.World_Objects.Particles.FireParticle particle in explosionParticles.ToList()) { particle.Update(gameTime); if (particle.Dead) { explosionParticles.Remove(particle); } } collisionRectangle = new Microsoft.Xna.Framework.Rectangle((int)wrldPstn.X, (int)wrldPstn.Y, 5, 5); explosionCheck = exploded; if (!exploded) { coreGraphic.Update(gameTime); tailGraphic.Update(gameTime); Vector2 moveAmount = velocity * elapsed; moveAmount = horizontalCollision(moveAmount, layer); moveAmount = verticalCollision(moveAmount, layer); Vector2 newPosition = new Vector2(wrldPstn.X + moveAmount.X, wrldPstn.Y + moveAmount.Y); if (hasCollidedHorizontally || hasCollidedVertically) { exploded = true; } wrldPstn = newPosition; worldLocation = new xTile.Dimensions.Location((int)wrldPstn.X, (int)wrldPstn.Y); } if (explosionCheck != exploded) { for (int i = 0; i < 90; i++) { explosionParticles.Add(new World_Objects.Particles.FireParticle( new Location( collisionRectangle.X + random.Next(0, 6), collisionRectangle.Y + random.Next(0, 6)), contentMgr)); } } if (exploded && explosionParticles.Count() == 0) { //enabled = false; } } }

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• How can I generate signed distance fields (2D) in real time, fast?

  - by heishe

  In a previous question, it was suggested that signed distance fields can be precomputed, loaded at runtime and then used from there. For reasons I will explain at the end of this question (for people interested), I need to create the distance fields in real time. There are some papers out there for different methods which are supposed to be viable in real-time environments, such as methods for Chamfer distance transforms and Voronoi diagram-approximation based transforms (as suggested in this presentation by the Pixeljunk Shooter dev guy), but I (and thus can be assumed a lot of other people) have a very hard time actually putting them to use, since they're usually long, largely bloated with math and not very algorithmic in their explanation. What algorithm would you suggest for creating the distance fields in real-time (favourably on the GPU) especially considering the resulting quality of the distance fields? Since I'm looking for an actual explanation/tutorial as opposed to a link to just another paper or slide, this question will receive a bounty once it's eligible for one :-). Here's why I need to do it in real time: There's something else:

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• Converting a DrawModel() using BasicEffect to one using Effect

  - by Fibericon

  Take this DrawModel() provided by MSDN: private void DrawModel(Model m) { Matrix[] transforms = new Matrix[m.Bones.Count]; float aspectRatio = graphics.GraphicsDevice.Viewport.Width / graphics.GraphicsDevice.Viewport.Height; m.CopyAbsoluteBoneTransformsTo(transforms); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); Matrix view = Matrix.CreateLookAt(new Vector3(0.0f, 50.0f, Zoom), Vector3.Zero, Vector3.Up); foreach (ModelMesh mesh in m.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.View = view; effect.Projection = projection; effect.World = gameWorldRotation * transforms[mesh.ParentBone.Index] * Matrix.CreateTranslation(Position); } mesh.Draw(); } } How would I apply a custom effect to a model with that? Effect doesn't have View, Projection, or World members. This is what they recommend replacing the foreach loop with: foreach (ModelMesh mesh in terrain.Meshes) { foreach (Effect effect in mesh.Effects) { mesh.Draw(); } } Of course, that doesn't really work. What else needs to be done?

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• write to depth buffer while using multiple render targets

  - by DocSeuss

  Presently my engine is set up to use deferred shading. My pixel shader output struct is as follows: struct GBuffer { float4 Depth : DEPTH0; //depth render target float4 Normal : COLOR0; //normal render target float4 Diffuse : COLOR1; //diffuse render target float4 Specular : COLOR2; //specular render target }; This works fine for flat surfaces, but I'm trying to implement relief mapping which requires me to manually write to the depth buffer to get correct silhouettes. MSDN suggests doing what I'm already doing to output to my depth render target - however, this has no impact on z culling. I think it might be because XNA uses a different depth buffer for every RenderTarget2D. How can I address these depth buffers from the pixel shader?

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• Best gui toolkit to use for creating 3D board game

  - by UserInteractive

  I have created a board game using Java and Swing - using GridLayout and various other apis. It works properly but the UI looks very very simple. I would want couple of animations like tilting the GridLayoutat any angle. There are pawns on boxes of the GridLayout that I want to be animated when somebody clicks on it. I'm not sure of the right GUI toolkit to use for this. Swing repaint is possible to a limit and cannot be used for a lot of animation and graphics. And I realized after creating the game that Swing is probably not a good tool to create games. Could anybody suggest a better framework to use that I can use it in Eclipse with Java? I was thinking of JavaFX or tools like Adobe Flash or Adobe Air. Any suggestions please?

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• X Error of failed request: BadMatch [migrated]

  - by Andrew Grabko

  I'm trying to execute some "hello world" opengl code: #include <GL/freeglut.h> void displayCall() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnable(GL_DEPTH_TEST); ... Some more code here glutSwapBuffers(); } int main(int argc, char *argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); glutInitWindowSize(500, 500); glutInitWindowPosition(300, 200); glutInitContextVersion(4, 2); glutInitContextFlags(GLUT_FORWARD_COMPATIBLE); glutCreateWindow("Hello World!"); glutDisplayFunc(displayCall); glutMainLoop(); return 0; } As a result I get: X Error of failed request: BadMatch (invalid parameter attributes) Major opcode of failed request: 128 (GLX) Minor opcode of failed request: 34 () Serial number of failed request: 39 Current serial number in output stream: 40 Here is the stack trace: fghCreateNewContext() at freeglut_window.c:737 0x7ffff7bbaa81 fgOpenWindow() at freeglut_window.c:878 0x7ffff7bbb2fb fgCreateWindow() at freeglut_structure.c:106 0x7ffff7bb9d86 glutCreateWindow() at freeglut_window.c:1,183 0x7ffff7bbb4f2 main() at AlphaTest.cpp:51 0x4007df Here is the last piece of code, after witch the program crashes: createContextAttribs = (CreateContextAttribsProc) fghGetProcAddress("glXCreateContextAttribsARB" ); if ( createContextAttribs == NULL ) { fgError( "glXCreateContextAttribsARB not found" ); } context = createContextAttribs( dpy, config, share_list, direct, attributes ); "glXCreateContextAttribsARB" address is obtained successfully, but the program crashes on its invocation. If I specify OpenGL version less than 4.2 in "glutInitContextVersion()" program runs without errors. Here is my glxinfo's OpelGL version: OpenGL version string: 4.2.0 NVIDIA 285.05.09 I would be very appreciate any further ideas.

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• Help understand GLSL directional light on iOS (left handed coord system)

  - by Robse

  I now have changed from GLKBaseEffect to a own shader implementation. I have a shader management, which compiles and applies a shader to the right time and does some shader setup like lights. Please have a look at my vertex shader code. Now, light direction should be provided in eye space, but I think there is something I don't get right. After I setup my view with camera I save a lightMatrix to transform the light from global space to eye space. My modelview and projection setup: - (void)setupViewWithWidth:(int)width height:(int)height camera:(N3DCamera *)aCamera { aCamera.aspect = (float)width / (float)height; float aspect = aCamera.aspect; float far = aCamera.far; float near = aCamera.near; float vFOV = aCamera.fieldOfView; float top = near * tanf(M_PI * vFOV / 360.0f); float bottom = -top; float right = aspect * top; float left = -right; // projection GLKMatrixStackLoadMatrix4(projectionStack, GLKMatrix4MakeFrustum(left, right, bottom, top, near, far)); // identity modelview GLKMatrixStackLoadMatrix4(modelviewStack, GLKMatrix4Identity); // switch to left handed coord system (forward = z+) GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeScale(1, 1, -1)); // transform camera GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeWithMatrix3(GLKMatrix3Transpose(aCamera.orientation))); GLKMatrixStackTranslate(modelviewStack, -aCamera.position.x, -aCamera.position.y, -aCamera.position.z); } - (GLKMatrix4)modelviewMatrix { return GLKMatrixStackGetMatrix4(modelviewStack); } - (GLKMatrix4)projectionMatrix { return GLKMatrixStackGetMatrix4(projectionStack); } - (GLKMatrix4)modelviewProjectionMatrix { return GLKMatrix4Multiply([self projectionMatrix], [self modelviewMatrix]); } - (GLKMatrix3)normalMatrix { return GLKMatrix3InvertAndTranspose(GLKMatrix4GetMatrix3([self modelviewProjectionMatrix]), NULL); } After that, I save the lightMatrix like this: [self.renderer setupViewWithWidth:view.drawableWidth height:view.drawableHeight camera:self.camera]; self.lightMatrix = [self.renderer modelviewProjectionMatrix]; And just before I render a 3d entity of the scene graph, I setup the light config for its shader with the lightMatrix like this: - (N3DLight)transformedLight:(N3DLight)light transformation:(GLKMatrix4)matrix { N3DLight transformedLight = N3DLightMakeDisabled(); if (N3DLightIsDirectional(light)) { GLKVector3 direction = GLKVector3MakeWithArray(GLKMatrix4MultiplyVector4(matrix, light.position).v); direction = GLKVector3Negate(direction); // HACK -> TODO: get lightMatrix right! transformedLight = N3DLightMakeDirectional(direction, light.diffuse, light.specular); } else { ... } return transformedLight; } You see the line, where I negate the direction!? I can't explain why I need to do that, but if I do, the lights are correct as far as I can tell. Please help me, to get rid of the hack. I'am scared that this has something to do, with my switch to left handed coord system. My vertex shader looks like this: attribute highp vec4 inPosition; attribute lowp vec4 inNormal; ... uniform highp mat4 MVP; uniform highp mat4 MV; uniform lowp mat3 N; uniform lowp vec4 constantColor; uniform lowp vec4 ambient; uniform lowp vec4 light0Position; uniform lowp vec4 light0Diffuse; uniform lowp vec4 light0Specular; varying lowp vec4 vColor; varying lowp vec3 vTexCoord0; vec4 calcDirectional(vec3 dir, vec4 diffuse, vec4 specular, vec3 normal) { float NdotL = max(dot(normal, dir), 0.0); return NdotL * diffuse; } ... vec4 calcLight(vec4 pos, vec4 diffuse, vec4 specular, vec3 normal) { if (pos.w == 0.0) { // Directional Light return calcDirectional(normalize(pos.xyz), diffuse, specular, normal); } else { ... } } void main(void) { // position highp vec4 position = MVP * inPosition; gl_Position = position; // normal lowp vec3 normal = inNormal.xyz / inNormal.w; normal = N * normal; normal = normalize(normal); // colors vColor = constantColor * ambient; // add lights vColor += calcLight(light0Position, light0Diffuse, light0Specular, normal); ... }

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