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Dynamic libraries are not allowed on iOS but what about this?

- by tapirath

I'm currently using LuaJIT and its FFI interface to call C functions from LUA scripts. What FFI does is to look at dynamic libraries' exported symbols and let the developer use it directly form LUA. Kind of like Python ctypes. Obviously using dynamic libraries is not permitted in iOS for security reasons. So in order to come up with a solution I found the following snippet. /* (c) 2012 +++ Filip Stoklas, aka FipS, http://www.4FipS.com +++ THIS CODE IS FREE - LICENSED UNDER THE MIT LICENSE ARTICLE URL: http://forums.4fips.com/viewtopic.php?f=3&t=589 */ extern "C" { #include <lua.h> #include <lualib.h> #include <lauxlib.h> } // extern "C" #include <cassert> // Please note that despite the fact that we build this code as a regular // executable (exe), we still use __declspec(dllexport) to export // symbols. Without doing that FFI wouldn't be able to locate them! extern "C" __declspec(dllexport) void __cdecl hello_from_lua(const char *msg) { printf("A message from LUA: %s\n", msg); } const char *lua_code = "local ffi = require('ffi') \n" "ffi.cdef[[ \n" "const char * hello_from_lua(const char *); \n" // matches the C prototype "]] \n" "ffi.C.hello_from_lua('Hello from LUA!') \n" // do actual C call ; int main() { lua_State *lua = luaL_newstate(); assert(lua); luaL_openlibs(lua); const int status = luaL_dostring(lua, lua_code); if(status) printf("Couldn't execute LUA code: %s\n", lua_tostring(lua, -1)); lua_close(lua); return 0; } // output: // A message from LUA: Hello from LUA! Basically, instead of using a dynamic library, the symbols are exported directly inside the executable file. The question is: is this permitted by Apple? Thanks.

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How to export 3D models that consist of several parts (eg. turret on a tank)?

- by Will

What are the standard alternatives for the mechanics of attaching turrets and such to 3D models for use in-game? I don't mean the logic, but rather the graphics aspects. My naive approach is to extend the MD2-like format that I'm using (blender-exported using a script) to include a new set of properties for a mesh that: is anchored in another 'parent' mesh. The anchor is a point and normal in the parent mesh and a point and normal in the child mesh; these will always be colinear, giving the child rotation but not translation relative to the parent point. has a normal that is aligned with a 'target'. Classically this target is the enemy that is being engaged, but it might be some other vector e.g. 'the wind' (for sails and flags (and smoke, which is a particle system but the same principle applies)) or 'upwards' (e.g. so bodies of riders bend properly when riding a horse up an incline etc). that the anchor and target alignments have maximum and minimum and a speed coeff. there is game logic for multiple turrets and on a model and deciding which engages which enemy. 'primary' and 'secondary' or 'target0' ... 'targetN' or some such annotation will be there. So to illustrate, a classic tank would be made from three meshes; a main body mesh, a turret mesh that is anchored to the top of the main body so it can spin only horizontally and a barrel mesh that is anchored to the front of the turret and can only move vertically within some bounds. And there might be a forth flag mesh on top of the turret that is aligned with 'wind' where wind is a function the engine solves that merges environment's wind angle with angle the vehicle is travelling in an velocity, or something fancy. This gives each mesh one degree of freedom relative to its parent. Things with multiple degrees of freedom can be modelled by zero-vertex connecting meshes perhaps? This is where I think the approach I outlined begins to feel inelegant, yet perhaps its still a workable system? This is why I want to know how it is done in professional games ;) Are there better approaches? Are there formats that already include this information? Is this routine?

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how difficult to add vibration/feedback to a open source driving game

- by Jonathan Day

Hi, I'm looking to use SuperTuxKart as a basis for a PhD research project. A key requirement for the game is to provide vibration feedback through the controller (obviously dependant on the controller itself). I don't believe that the game currently includes this feature and I'm trying to get a feel for how big a challenge it would be to add. My background is as a J2EE and PHP developer/architect, so I don't know C++ as such, but am prepared to give it a crack if there are resources and guides to assist, and it's not a herculean task. Alternatively, if you know of any open source games that do include vibration feedback, please feel free to let me know! Preferably the game would be of the style that the player had to navigate a character (or character's vehicle) over a repeatable course/map. TIA, JD

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Apply bone tranforms when importing FBX in XNA

- by hichaeretaqua

Preconditions: I have some models, that does only contain some meshes and one texture. There is no animation within the model. An example: a model of a table. I want to draw the Model with a custom effect, so I have to swap the effect after loading the model. In order to draw them correctly, I have to apply the bone transformation manually on each draw for each mesh and effect as can be seen here. So there are two questions: Is there a option during import that allows my to apply the bone transformation on all vertices, so that during draw call I should not have to do this? Is there a option during import that merges all vertices into a Vertex- and IndexBuffer, that allows me to draw the whole model with just one call? I'm pretty sure that the build-in "Autodesk FBX - XNA Framework" does not support this features, but maybe there is an other imported available or an other possibility I missed. The aim is to speed up rendering a little bit especially by using instancing. So having one VertexBuffer to draw at one time would be pretty nice.

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how to transform child elements position into a world position

- by MrGreg

So Im making a 2d space game and I have a bunch of spaceships that have turrets. Objects have a position and orientation, the ships being in world coordinates while the turrets are children and coordinates are relative to their parents. How do I efficiently calculate the position of a turret in world coordinates (i.e. when it fires and I need to know where to place a bullet in the world)? Calculating the turrets orientation is trivial - I just add the turrets relative angle to its parents. For position though, I guess I could do a bunch of trigonometry but this MUST be a common problem with a good/fast general solution? Should I be relearning how to do matrix math again? :) btw - Im creating the game in javascript+canvas but its the math/algorithm im interested in here Cheers, Greg

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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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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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CCUserDefault, iOS/Android and game updates

- by Luke

My game uses cocos2d-x and will be published on iOS platform first, later on Android. I save a lot of things with CCUserDefault (scores, which level was completed, number of coins taken, etc...). But now I have a big doubt. What will happen when the game will receive its first update? CCUserDefault uses an XML file stored somewhere in the app storage space. This file is created and retained until one uninstalls the app. I am wondering what happens when the app is updated. Will the old XML file be maintained? Because if not, how should I handle app updates (updates in the sense that 2, 3 or more new level packages will be added, but the informations about the old ones, like scores, which level was finished and which not, number of coins, etc., need absolutely not to be lost)?

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IDirect3DDevice9Ex and D3DPOOL_MANAGED?

- by bluescrn

So I wanted to switch to IDirect3DDevice9Ex, purely for the SetFrameLatency function, as fullscreen vsynced D3D seemed to produce noticable input lag. But then it tells me 'ha ha ha! now you can't use D3DPOOL_MANAGED!': Direct3D9: (ERROR) :D3DPOOL_MANAGED is not valid with IDirect3DDevice9Ex Is this really as unpleasant as it looks (when you're relying quite heavily on managed resources) - or is there a simple solution? If it really does mean manual management of everything (reloading all static textures, VBs, and IBs on a device reset), is it worth the hassle, will IDirect3DDevice9Ex bring enough benefit to make it worth writing a new resource manager? Starting to think I must be doing something wrong, due to this: Direct3D9: (ERROR) :Lock is not supported for textures allocated with POOL_DEFAULT unless they are marked D3DUSAGE_DYNAMIC. So if I put my (static) textures in POOL_DEFAULT, they need flagging as D3DUSAGE_DYNAMIC, just because I lock them once to load the data in?

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Collision and Graphics integration

- by Shlomi Atia

I'm a little confused about the integration between collision and graphics. They both need to share the same position in the world. The most obvious choice is the center of the entity, which is good for bounding volumes and fixed sized sprites. However, for characters with variable height size sprites like this: http://gamemedia.wcgame.ru/data/2011-07-17/game-sprite-sheet.jpg This is no longer good. The character won't align to the ground if I'll draw it from the center. I can just make the sprites the same height, but it will be a waste of memory (the largest sprite is 4 times larger then the smallest one). Even then, this is not an option at all with skeletal sprites like this one: http://user-generated-content.java-gaming.org/img-vault/212a171fc1ebb27ab77608fb9b2dd9bd9205361ce6300b21a7f8d06d025fbbd8.png It seems that the graphics need to be drawn from the ground for characters, but not for other images such as scenery and obstacles. The only solution I could think of was having another position called draw-position, which is the entity center for images, and is the the bottom of the collision volume for characters. Then when I draw relative to that position, it should work properly. I haven't found any references for something like that, so I'm kinda insecure about it. Does anyone knows of a better approach for this problem? Thanks

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Importing 3d model with multiple skeletons

- by Sweta Dwivedi

I have created an animated butterfly in 3ds Max and try to export it in ".fbx" format to use in XNA, however as soon as I compile, i get the following Errors: Warning 1 Multiple skeletons were found in the file. The first skeleton, named "Left.Wing" has been moved to be a child of the scene root. The other, "Right.Wing", will be ignored. Fragment identifier "Right.Wing". Error 2 Vertex is bound to bone "Right.Wing", but this bone is not present in the skeleton. Which is confusing since I have the bone Right.Wing . . and I use it to animate the butterfly I have seen a few possible solution for Blender but none for 3Ds max it would be really helpful if someone could help me out with this

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collision detection problems - Javascript/canvas game

- by Tom Burman

Ok here is a more detailed version of my question. What i want to do: i simply want the have a 2d array to represent my game map. i want a player sprite and i want that sprite to be able to move around my map freely using the keyboard and also have collisions with certain tiles of my map array. i want to use very large maps so i need a viewport. What i have: I have a loop to load the tile images into an array: /Loop to load tile images into an array var mapTiles = []; for (x = 0; x <= 256; x++) { var imageObj = new Image(); // new instance for each image imageObj.src = "images/prototype/"+x+".jpg"; mapTiles.push(imageObj); } I have a 2d array for my game map: //Array to hold map data var board = [ [1,2,3,4,3,4,3,4,5,6,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [17,18,19,20,19,20,19,20,21,22,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [33,34,35,36,35,36,35,36,37,38,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [49,50,51,52,51,52,51,52,53,54,1,1,1,1,1,1,1,1,1,1,1,1,1,197,198,199,1,1,1,1], [65,66,67,68,146,147,67,68,69,70,1,1,1,1,1,1,1,1,216,217,1,1,1,213,214,215,1,1,1,1], [81,82,83,161,162,163,164,84,85,86,1,1,1,1,1,1,1,1,232,233,1,1,1,229,230,231,1,1,1,1], [97,98,99,177,178,179,180,100,101,102,1,1,1,1,59,1,1,1,248,249,1,1,1,245,246,247,1,1,1,1], [1,1,238,1,1,1,1,239,240,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [216,217,254,1,1,1,1,255,256,1,204,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [232,233,1,1,1,117,118,1,1,1,220,1,1,119,120,1,1,1,1,1,1,1,1,1,1,1,119,120,1,1], [248,249,1,1,1,133,134,1,1,1,1,1,1,135,136,1,1,1,1,1,1,59,1,1,1,1,135,136,1,1], [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,216,217,1,1,1,1,1,1,60,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,232,233,1,1,1,1,1,1,1,1,1,1,1,1,1,1,204,1,1,1,1,1,1,1,1,1,1,1], [1,1,248,249,1,1,1,1,1,1,1,1,1,1,1,1,1,1,220,1,1,1,1,1,1,216,217,1,1,1], [1,1,1,1,1,1,1,1,1,1,1,1,149,150,151,1,1,1,1,1,1,1,1,1,1,232,233,1,1,1], [12,12,12,12,12,12,12,13,1,1,1,1,165,166,167,1,1,1,1,1,1,119,120,1,1,248,249,1,1,1], [28,28,28,28,28,28,28,29,1,1,1,1,181,182,183,1,1,1,1,1,1,135,136,1,1,1,1,1,1,1], [44,44,44,44,44,15,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,59,1,1,197,198,199,1,1,1,1,119,120,1], [1,1,1,1,1,27,28,29,1,1,216,217,1,1,1,1,1,1,1,1,213,214,215,1,1,1,1,135,136,1], [1,1,1,1,1,27,28,29,1,1,232,233,1,1,1,1,1,1,1,1,229,230,231,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,248,249,1,1,1,1,1,1,1,1,245,246,247,1,1,1,1,1,1,1], [1,1,1,197,198,199,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,213,214,215,28,29,1,1,1,1,1,60,1,1,1,1,204,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,229,230,231,28,29,1,1,1,1,1,1,1,1,1,1,220,1,1,1,1,119,120,1,1,1,1,1], [1,1,1,245,246,247,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,135,136,1,1,60,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1], [1,1,1,1,1,27,28,29,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1] ]; I have my loop to place the correct tile sin the correct positions: //Loop to place tiles onto screen in correct position for (x = 0; x <= viewWidth; x++){ for (y = 0; y <= viewHeight; y++){ var width = 32; var height = 32; context.drawImage(mapTiles[board[y+viewY][x+viewX]],x*width, y*height); } } I Have my player object : //Place player object context.drawImage(playerImg, (playerX-viewX)*32,(playerY-viewY)*32, 32, 32); I have my viewport setup: //Set viewport pos viewX = playerX - Math.floor(0.5 * viewWidth); if (viewX < 0) viewX = 0; if (viewX+viewWidth > worldWidth) viewX = worldWidth - viewWidth; viewY = playerY - Math.floor(0.5 * viewHeight); if (viewY < 0) viewY = 0; if (viewY+viewHeight > worldHeight) viewY = worldHeight - viewHeight; I have my player movement: canvas.addEventListener('keydown', function(e) { console.log(e); var key = null; switch (e.which) { case 37: // Left if (playerY > 0) playerY--; break; case 38: // Up if (playerX > 0) playerX--; break; case 39: // Right if (playerY < worldWidth) playerY++; break; case 40: // Down if (playerX < worldHeight) playerX++; break; } My Problem: I have my map loading an it looks fine, but my player position thinks it's on a different tile to what it actually is. So for instance, i know that if my player moves left 1 tile, the value of that tile should be 2, but if i print out the value it should be moving to (2), it comes up with a different value. How ive tried to solve the problem: I have tried swap X and Y values for the initialization of my player, for when my map prints. If i swap the x and y values in this part of my code: context.drawImage(mapTiles[board[y+viewY][x+viewX]],x*width, y*height); The map doesnt get draw correctly at all and tiles are placed all in random positions or orientations IF i sway the x and y values for my player in this line : context.drawImage(playerImg, (playerX-viewX)*32,(playerY-viewY)*32, 32, 32); The players movements are inversed, so up and down keys move my player left and right viceversa. My question: Where am i going wrong in my code, and how do i solve it so i have my map looking like it should and my player moving as it should as well as my player returning the correct tileID it is standing on or moving too. Thanks Again ALSO Here is a link to my whole code: prototype

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graphical interface when using assembly language

- by Hellbent

Im looking to use assembly language to make a great game, not just an average game but a really great game. I want to learn a framework to use in assembly. I know thats not possible without learning the framework in c first. So im thinking of learning sdl in c and then learn, teach myself, how to interpret the program and run it as assembly language code which shouldnt be that hard. Then i will have a window and some graphics routines to display the game while using assembly to code everything in. I need to spend some time learning sdl and then some more time learning how to code all those statements using assembly while calling c functions and knowing what registers returned calls use and what they leave etc. My question is , Is this a good way to go or is there something better to get a graphical window display using assembly language? Regards HellBent

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Amazon Adds Messaging to its Web Services

New tool eliminates the need for cloud developers to create their own messaging capabilities.

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Amazon Adds Messaging to its Web Services

New tool eliminates the need for cloud developers to create their own messaging capabilities.

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2D basic map system

- by Cyril

i'm currently coding a 2D game in Java, and I would like to have some clues on how-to build this system : the screen is moving on a grander map, for instance, the screen represent 800*600 units on a 100K*100K map. When you command your unit to go to another position, the screen move on this map AND when you move your mouse on a side or another of the screen, you move the screen on the map. Not sure that i'm clear, but we can retrieve this system in most RTS games (warcraft/starcraft for example). I'm currently using Slick 2D. Any idea ? Thanks.

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Slick & NiftyGUI. Nifty initialize exception

- by Romeo

I found my self into trouble when trying to run a Slick game with a Nifty Game State. This is the code: @Override protected void initGameAndGUI(GameContainer container, StateBasedGame game) throws SlickException { initNifty(container, game); } If i run this i get: java.lang.IllegalStateException: The NiftyGUI was already initialized. Its illegal to do so twice. If i delete the call to initNifty() i get another exception:java.lang.IllegalStateException: NiftyGUI was not initialized.

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What makes games responsive to user input?

- by zaftcoAgeiha

Many games have been praised for its responsive gameplay, where each user action input correspond to a quick and precise character movement (eg: super meat boy, shank...) What makes those games responsive? and what prevents other games from achieving the same? How much of it is due to the game framework used to queue mouse/keyboard events and render/update the game and how much is attributed to better coding?

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Variables in static library are never initialized. Why?

- by Coyote

I have a bunch of variables that should be initialized then my game launches, but must of them are never initialized. Here is an example of the code: MyClass.h class MyClass : public BaseObject { DECLARE_CLASS_RTTI(MyClass, BaseObject); ... }; MyClass.cpp REGISTER_CLASS(MyClass) Where REGISTER_CLASS is a macro defined as follow #define REGISTER_CLASS(className)\ class __registryItem##className : public __registryItemBase {\ virtual className* Alloc(){ return NEW className(); }\ virtual BaseObject::RTTI& GetRTTI(){ return className::RTTI; }\ }\ \ const __registryItem##className __registeredItem##className(#className); and __registryItemBase looks like this: class __registryItemBase { __registryItemBase(const _string name):mName(name){ ClassRegistry::Register(this); } const _string mName; virtual BaseObject* Alloc() = 0; virtual BaseObject::RTTI& GetRTTI() = 0; } Now the code is similar to what I currently have and what I have works flawlessly, all the registered classes are registered to a ClassManager before main(...) is called. I'm able to instantiate and configure components from scripts and auto-register them to the right system etc... The problem arrises when I create a static library (currently for the iPhone, but I fear it will happen with android as well). In that case the code in the .cpp files is never registered. Why is the resulting code not executed when it is in the library while the same code in the program's binary is always executed? Bonus questions: For this to work in the static library, what should I do? Is there something I am missing? Do I need to pass a flag when building the lib? Should I create another structure and init all the __registeredItem##className using that structure?

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Bitmap Font Displays in Center Always Without Coding it Manually (Fix Coordinate Problem onText)

- by David Dimalanta

Is there a way on how to stay the texts in center without manually coding it or something, especially when making an update? I'm making a display for the highest score. Let's say that the score is 9. However, if the score is 9,999,999, the text displays still only at the fixed X and Y coordinate. Is there really a way to stay the text in center especially when there is changes when a player beats the new world record? Here's my code inside Sprite Batch: font.setScale(1.5f); font.draw(batch, "HIGHEST SCORE:", (900/10)*1 + 60, (1280/16)*10); font.draw(batch, "" + 9999999 + "", (900/10)*4, (1280/16)*8); batch.draw(grid_guide, 0, 0, 900, 1280); // --> For testing purpose only. // Where 9999999 is a new record score for example. Here's the image shown as example. I add it some red grid so that I could check if the display of score when updated will always display on center no matter how many digits takes place in. However, it is fixed, so I have to figure it out how to display it automatically on center regardless of the number of digits while updating for the new highscore. I have used the LibGDX preferences very well though to save and load records for the highscore.

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Smooth waypoint traversing

- by TheBroodian

There are a dozen ways I could word this question, but to keep my thoughts in line, I'm phrasing it in line with my problem at hand. So I'm creating a floating platform that I would like to be able to simply travel from one designated point to another, and then return back to the first, and just pass between the two in a straight line. However, just to make it a little more interesting, I want to add a few rules to the platform. I'm coding it to travel multiples of whole tile values of world data. So if the platform is not stationary, then it will travel at least one whole tile width or tile height. Within one tile length, I would like it to accelerate from a stop to a given max speed. Upon reaching one tile length's distance, I would like it to slow to a stop at given tile coordinate and then repeat the process in reverse. The first two parts aren't too difficult, essentially I'm having trouble with the third part. I would like the platform to stop exactly at a tile coordinate, but being as I'm working with acceleration, it would seem easy to simply begin applying acceleration in the opposite direction to a value storing the platform's current speed once it reaches one tile's length of distance (assuming that the tile is traveling more than one tile-length, but to keep things simple, let's just assume it is)- but then the question is what would the correct value be for acceleration to increment from to produce this effect? How would I find that value?

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Love2D engine for Lua; What about 3D?

- by shadowprotocol

Lua has been really awesome to learn, it's so simple. I really enjoy scripting languages, and I had an equally enjoyable time learning Python. The Love engine, http://love2d.org/, is really awesome, but I'm looking for something that can handle 3D as well. Is there anything that accommodates 3D in Lua? I'm still intrigued by the particle system of LOVE anyway and may just turn my idea into a 2D project with Particle lighting :) EDIT: I removed comments about Python - I want this to be a Lua topic. Thanks

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One True Event Loop

- by CyberShadow

Simple programs that collect data from only one system need only one event loop. For example, Windows applications have the message loop, POSIX network programs usually have a select/epoll/etc. loop at their core, pure SDL games use SDL's event loop. But what if you need to collect events from several subsystems? Such as an SDL game which doesn't use SDL_net for networking. I can think of several solutions: Polling (ugh) Put each event loop in its own thread, and: Send messages to the main thread, which collects and processes the events, or Place the event-processing code of each thread in a critical section, so that the threads can wait for events asynchronously but process them synchronously Choose one subsystem for the main event loop, and pass events from other subsystems via that subsystem as custom messages (for example, the Windows message loop and custom messages, or a socket select() loop and passing events via a loopback connection). Option 2.1 is more interesting on platforms where message-passing is a well-developed threading primitive (e.g. in the D programming language), but 2.2 looks like the best option to me.

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Pathfinding for fleeing

- by Philipp

As you know there are plenty of solutions when you wand to find the best path in a 2-dimensional environment which leads from point A to point B. But how do I calculate a path when an object is at point A, and wants to get away from point B, as fast and far as possible? A bit of background information: My game uses a 2d environment which isn't tile-based but has floating point accuracy. The movement is vector-based. The pathfinding is done by partitioning the game world into rectangles which are walkable or non-walkable and building a graph out of their corners. I already have pathfinding between points working by using Dijkstras algorithm. The use-case for the fleeing algorithm is that in certain situations, actors in my game should perceive another actor as a danger and flee from it. The trivial solution would be to just move the actor in a vector in the direction which is opposite from the threat until a "safe" distance was reached or the actor reaches a wall where it then covers in fear. The problem with this approach is that actors will be blocked by small obstacles they could easily get around. As long as moving along the wall wouldn't bring them closer to the threat they could do that, but it would look smarter when they would avoid obstacles in the first place: Another problem I see is with dead ends in the map geometry. In some situations a being must choose between a path which gets it faster away now but ends in a dead end where it would be trapped, or another path which would mean that it wouldn't get that far away from the danger at first (or even a bit closer) but on the other hand would have a much greater long-term reward in that it would eventually get them much further away. So the short-term reward of getting away fast must be somehow valued against the long-term reward of getting away far. There is also another rating problem for situations where an actor should accept to move closer to a minor threat to get away from a much larger threat. But completely ignoring all minor threats would be foolish, too (that's why the actor in this graphic goes out of its way to avoid the minor threat in the upper right area): Are there any standard solutions for this problem?

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Stop a rotating object at a specified angle?

- by Krummelz

I'm working in JavaScript with HTML5 and the canvas. I have an object which is rotating at a certain speed, and I need the object's rotation to slow down gradually and the front of the object to stop at a specified angle. (I'm using radians, not degrees.) I have a variable to keep track of the angle which the object is facing, as it rotates. How would I go about getting the object to come to rest, facing the direction I want it to?

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