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  • XNA Windows Phone 7 Sprite movement

    - by Darren Gaughan
    I'm working on a Windows phone game and I'm having difficulty with the sprite movement. What I want to do is make the sprite gradually move to the position that is touched on screen, when there is only one quick touch and release. At the minute all I can do is either make the sprite jump instantly to the touch location or move along to the touch location when the touch is held down. Code for jumping to touch location: TouchCollection touchCollection = TouchPanel.GetState(); foreach (TouchLocation tl in touchCollection) { if ((tl.State == TouchLocationState.Pressed) || (tl.State == TouchLocationState.Moved)) { Vector2 newPos = new Vector2(tl.Position.X,tl.Position.Y); if (position != newPos) { while (position.X < newPos.X) { position.X += (float)theGameTime.ElapsedGameTime.Milliseconds / 10.0f * spriteDirectionRight; } } } } Code to gradually move along while touch is held: TouchCollection touchCollection = TouchPanel.GetState(); foreach (TouchLocation tl in touchCollection) { if ((tl.State == TouchLocationState.Pressed) || (tl.State == TouchLocationState.Moved)) { Vector2 newPos = new Vector2(tl.Position.X,tl.Position.Y); if (position != newPos) { position.X += (float)theGameTime.ElapsedGameTime.Milliseconds / 10.0f * spriteDirectionRight; } } } These are in the Update() method of the Sprite class.

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  • Deforming surfaces

    - by Constantin
    I try to accomplish an deforming physic behaviour for levelsurfaces, but don't get an idea how to start with the implemenation so far. Regardless of the shape from the surface (planes, cubes, spheres…), I want to have small indentations at the positions from game-entitys (players, enemys, objects…). It's kind of complicated to explain, so I illustrated what I'm talking about (here is an example with an sphere): So, the surfaces should be able to deforming themselfs a little bit (to apear like an really soft bed or sofa). My surfaces need probably an high vertices count to get an smooth deforming, but my big problem is the math for calculating this deforming… I'm programming in C/C++ with OpenGL, but will be fine with any advices in the right direction. Any help would be highly appreciated,

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  • How do you make a bullet ricochet off a vertical wall?

    - by Bagofsheep
    First things first. I am using C# with XNA. My game is top-down and the player can shoot bullets. I've managed to get the bullets to ricochet correctly off horizontal walls. Yet, despite using similar methods (e.g. http://stackoverflow.com/questions/3203952/mirroring-an-angle) and reading other answered questions about this subject I have not been able to get the bullets to ricochet off a vertical wall correctly. Any method I've tried has failed and sometimes made ricocheting off a horizontal wall buggy. Here is the collision code that calls the ricochet method: //Loop through returned tile rectangles from quad tree to test for wall collision. If a collision occurs perform collision logic. for (int r = 0; r < returnObjects.Count; r++) if (Bullets[i].BoundingRectangle.Intersects(returnObjects[r])) Bullets[i].doCollision(returnObjects[r]); Now here is the code for the doCollision method. public void doCollision(Rectangle surface) { if (Ricochet) doRicochet(surface); else Trash = true; } Finally, here is the code for the doRicochet method. public void doRicochet(Rectangle surface) { if (Position.X > surface.Left && Position.X < surface.Right) { //Mirror the bullet's angle. Rotation = -1 * Rotation; //Moves the bullet in the direction of its rotation by given amount. moveFaceDirection(Sprite.Width * BulletScale.X); } else if (Position.Y > surface.Top && Position.Y < surface.Bottom) { } } Since I am only dealing with vertical and horizontal walls at the moment, the if statements simply determine if the object is colliding from the right or left, or from the top or bottom. If the object's X position is within the boundaries of the tile's X boundaries (left and right sides), it must be colliding from the top, and vice verse. As you can see, the else if statement is empty and is where the correct code needs to go.

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  • How to create Button/Switch-Like Tile where you can step on it and change its value?

    - by aldroid16
    If the player step on Button-Tile when its true, it become false. If the player step on Button-Tile when its false, it become true. The problem is, when the player stand on (intersect) the Button-Tile, it will keep updating the condition. So, from true, it become false. Because its false and player intersect on it, it become true again. True-false-true-false and so on. I use ElapsedGameTime to make the updating process slower, and player can have a chance to change the Button to true or false. However, its not a solution I was looking for. Is there any other way to make it keep in False/True condition while the Player standing on it (The Button tile) ?

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  • Implementing AS 2.0 with FSM?

    - by Up2u
    i have seen many of references of AI and FSM like : http://www.richardlord.net/blog/fini...n-actionscript and sadly im still can't understand the point of the FSM on AS2.0 is it a must to create a class of each state ? i have a project of game and also it has an AI, the AI has 3 state n i said the state is distanceCheck, ChaseTarget, and Hit the target, the game that i create is FPS game and play via by mouse so what i mean is i have create an AI ( and is success ) but i want to convert it to FSM method ... i create : function of CheckDistanceState() and in that function i have to locked the target with an array, and sort it with the nearest distance and locked it and it trigger the function ChaseState(), and in the ChaseState() i insert the Hit() function to destroy the enemy, the 3 function that i created , i call it in the AI_cursor.onEnterframe, ( FPS game that only have a cursor in stage ) is there any chance to implement FSM to my code without to create a class ?? from what i read before , to create a class mean to create an external code outside of the frame ( i used to code in frame) and i stil dont understand about it. sorry if my explaination not clear ...

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  • OutOfBounds Exception when creating a PolygonShape using jbox2d

    - by B3nGr33ni3r
    So here's the deal, i'm parsing a file that contains the vertices for a polygon, that i want to create in box2d. I create a new PolygonShape() and then call .set() giving it a defined array of Vec, and that defined array's .length property. I expected this to work, since the documentation for jbox2d says this method takes a Vec array, and the count of Vec objects in that array. However, it errors out, and it seems to be unrelated to my code. The error i get is Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 8 at org.jbox2d.collision.shapes.PolygonShape.set(PolygonShape.java:174) and, upon looking at that line in the jbox2d svn repository, i still cannot figure out the issue. Any help is appreciated!

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  • Detailed Modern Opengl Tutorial?

    - by Kogesho
    I am asking for a specific modern opengl tutorial. I need a tutorial that does not skip to explain any lines of code. It should also include different independent objects moving/rotating (most tutorials use only one object), as well as imported 3d objects and collision detection for them. It should also avoid stuff that won't be used. Arcysnthesis for example gives a new concept, and after teaching it, in the next tutorial, it explains how bad it is for performance and introduces another method. Do you know any?

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  • GLES2.0 3D Android game performance and multi threading the update?

    - by Ofer
    I have profiled my mixed Java\C++ Android game and I got the following result: https://dl.dropbox.com/u/8025882/PompiDev/AndroidProfile.png As you can see, the pink think is a C++ functions that updates the game. It does things like updating the logic but it mostly it generates a "request list" for rendering. The thing is, I generate DrawLists on C++ and then send them to Java to process and draw using GLES2.0. Since then I was able to improve update from 9ms down to about 7ms, but I would like to ask if I would benefit from multi threading the update? As I understand from that diagram is that the function that takes the most time is the one you see it's color on the timeline. So the pink area is taken mostly by update. The other area has MainOpenGL.Handle as it's main contributor(whch is my java function), but since it's not drawn to the top of the diagram I can conclude other things are happening at the same time that use the CPU? Or even GPU stuff that isn't shown in this diagram. I am not sure how the GPU works on this. Does it calculate stuff in parallel to the CPU? Or is it part of the CPU usage as in SoC? I am not sure. Anyway, in case GPU things DO happen in parallel to CPU, then I would guess that if I do this C++ Update in parallel to the thread that makes the OpenGL calls, I might make use of "dead CPU time" due to GPU stalling or maybe have the GPU calls getting processed earlier because it won't have to wait for Update to finish? How do you suggest to improve performance based on that? Thanks.

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  • Can various browsers be assumed to maintain predictible state accurately in multiplayer online gaming?

    - by Nikos
    With many games it is said that server will assume that clients keep track of the world accurately. Assuming this is true, for a browser based multiplier space invaders game you would only tell the client when new bullets or the players ship moves and everything that behaves in a predetermined manner in the js client. It would be expected that positions would be the same in the browsers. Do you think you could trust browsers to do this? I feel that timings could differ between rendering loops and cause positions to get out of sync and might just get the server to maintain all the positions to make sure.

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  • FPS camera specification

    - by user1095108
    I remember I once composed a FPS viewing transformation, as a composition of 3 rotations, each with an angle as a parameter. The first angle specified the left/right rotation around the y-axis, the second angle the up/down rotation around the x-axis, and the third around the z-axis. The viewing transformation was therefore specified by 3 angles. Naturally, this transformation had a gimbal lock, depending in what order the transformation were performed. What should I look at to derive my viewing transformation without the gimbal lock? I know the "lookAt" method already, but I consider that cumbersome. EDIT: MY first guess is to do the first 2 transformations to get a viewing direction and then the axis-angle rotation on this axis.

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  • XNA 4: RenderTarget2D textures getting transparent on fullscreen

    - by Shashwat
    I'm generating a Texture2D object using RenderTarget2D as in the following code public static Texture2D GetTextTexture(string text, Vector2 position, SpriteFont font, Color foreColor, Color backColor, Texture2D background=null) { int width = (int)font.MeasureString(text).X; int height = (int)font.MeasureString(text).Y; GraphicsDevice device = Settings.game.GraphicsDevice; SpriteBatch spriteBatch = Settings.game.spriteBatch; RenderTarget2D renderTarget = new RenderTarget2D(device, width, height, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, device.PresentationParameters.MultiSampleCount, RenderTargetUsage.DiscardContents); device.SetRenderTarget(renderTarget); device.Clear(backColor); spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Opaque); if (background != null) spriteBatch.Draw(background, new Rectangle(0, 0, 70, 70), Color.White); spriteBatch.End(); spriteBatch.Begin(); spriteBatch.DrawString(font, text, position, foreColor, 0, new Vector2(0), 0.8f, SpriteEffects.None, 0); spriteBatch.End(); device.SetRenderTarget(null); ResetGraphicsDeviceSettings(); return (Texture2D)renderTarget; } It's working all fine. But when I ToggleFullScreen() (and vice-versa), the previous textures are getting transparent. However, the new textures after that are being generated correctly. What can be the reason for this?

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  • Who should respond to collision: Unit or projectile?

    - by aleguna
    In an RTS if a projectile hits a unit. Who should handle the collision? If projectile handles the collision, it must be aware of all possible types of units, to know what damage to inflict. For example a bullet will likely kill a human, but it will do nothing to a tank. The same goes if unit handles a collision. So either way one of them should be aware of all possible types of the other. Of course the 'true' way would be to do full physics simulation, but that's not an option for an RTS with 1000s of units and projectiles... So what are the common practicies in this regards?

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  • Shared Object Not saving the level Progress

    - by user3536228
    I am making a flash game in which i have a variable levelState that describes the current level in which user has entered I am using SharedObject to save the progress but it does not do so first i declred a clas level variable private var levelState:Number = 1; private var mySaveData:SharedObject = SharedObject.getLocal("levelSave"); in the Main function i am checking if it is a first run of the game like below if (mySaveData.data.levelsComplete == null) { mySaveData.data.levelsComplete = 1; } and in a function where the winning condition is checked so that levelState could be increased i am usin this sharedobject to hold the value of levelState if (/*winniing condition*/) levelState++; mySaveData.data.levelsComplete = levelState; mySaveData.flush(); setNewLevel(levelState); } but when i play the game clear a level and again run the game it does not start from that level it starts from beginning.

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  • Point in Polygon, Ray Method: ending infinite line

    - by user2878528
    Having a bit of trouble with point in polygon collision detection using the ray method i.e. http://en.wikipedia.org/wiki/Point_in_polygon My problem is I need to give an end to the infinite line created. As with this infinite line I always get an even number of intersections and hence an invalid result. i.e. ignore or intersection to the right of the point being checked what I have what I want My current code based of Mecki awesome response for (int side = 0; side < vertices.Length; side++) { // Test if current side intersects with ray. // create infinite line // See: http://en.wikipedia.org/wiki/Linear_equation a = end_point.Y - start_point.Y; b = start_point.X - end_point.X; c = end_point.X * start_point.Y - start_point.X * end_point.Y; //insert points of vector d2 = a * vertices[side].Position.X + b * vertices[side].Position.Y + c; if (side - 1 < 0) d1 = a * vertices[vertices.Length - 1].Position.X + b * vertices[vertices.Length - 1].Position.Y + c; else d1 = a * vertices[side-1].Position.X + b * vertices[side-1].Position.Y + c; // If points have opposite sides, intersections++; if (d1 > 0 && d2 < 0 ) intersections++; if (d1 < 0 && d2 > 0 ) intersections++; } //if intersections odd inside = true if ((intersections % 2) == 1) inside = true; else inside = false;

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  • Is the TCP protocol good enough for real-time multiplayer games?

    - by kevin42
    Back in the day, TCP connections over dialup/ISDN/slow broadband resulted in choppy, laggy games because a single dropped packet resulted in a resync. That meant a lot of game developers had to implement their own reliability layer on top of UDP, or they used UDP for messages that could be dropped or received out of order, and used a parallel TCP connection for information that must be reliable. Given the average user has faster network connections now, can a real time game such as an FPS give good performance over a TCP connection?

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  • How do I multiply pixels on an SDL Surface?

    - by NoobScratcher
    Okay so I'm able to put blank pixels into a surface and also draw gradient pixels rectangles,etc But I don't know how to multiply the pixels on a surface so I was hoping someone could provide me information on this topic. I was thinking you could get the members pixel and then * it by 2 but that didn't provide results I wanted so I'm now thinking that you have to actually get to the position in bytes in one location to the left and one location to the right and then store it in memory and then * that by 2 am I correct or what? If so what is it that allows me to do that and how do I do that?

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  • C++ Framework for iOS [closed]

    - by myrkos
    I am looking for a simple and easy C++ framework for iOS. Specifically, what I want it to wrap in a C++ API: Simple GUI system 2D Graphics User touch input and accelerometer Networking (UDP sockets) What I'm trying to do is port a multiplayer game to the iOS. I've seen cocos2d-x, but I don't know how stable it is and I don't think it supports networking. Oh, and I want it to be free and open source if possible. Android support is a plus but definitely not required.

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  • Character coding / programming

    - by Jery
    Lately I tryed a few times to create characters for some games, but at some certain point (especially when collision detection came in) everything became messy and the interaction between chars, the world and certain items had a lot of bugs. So here is my question, how do you ussualy keep track of actions that your character is allowed to do, or more in general do you have some links / advices how to set up a char efficiantly? I´m working on a char right now, who should at least be able to run, jump, pick items up and use different fighting animations. Most ideas I came up with until now use some kind of action.priority / action.duration system to determain whats possible and what not, or a "action-manager" which defines for every action what is possible from that action on but it all doesnt work that well together.

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  • Best way to calculate unit deaths in browser game combat?

    - by MikeCruz13
    My browser game's combat system is written and mechanically functioning well. It's written in PHP and uses a SQL database. I'm happy with the unit balance in relation to one another. I am, however, a little worried about how I'm calculating unit deaths when one player attacks another because the deaths seem to pile up a little fast for my taste. For this system, a battle doesn't just trigger, calculate winner, and end. Instead, it is allowed to go for several rounds (say one round every 15 mins.) until one side passes a threshold of being too strong for the other player and allows players to send reinforcements between rounds. Each round, units pair up and attack each other. Essentially what I do is calculate the damage: AP = Attack Points HP = Hit Points Units AP * Quantity * Random Factors * other factors (such as attrition) I take that and divide by the defending unit's HP to find the number of casualties of defending units. So, for example (simplified to take out some factors), if I have: 500 attackers with 50 AP vs 1000 defenders with 100 HP = 250 deaths. I wonder if that last step could be handled better to reduce the deaths piling up. Some ideas: I just change all the units with more HP? I make sure to set the Attacking unit's AP to be a max of the defender's HP to make sure they only kill 1 unit. (is that fair if I have less huge units vs many small units?) I spread the damage around more by including the defending unit's quantity more? i.e. in that scenario some are dead and some are 50% damage. (How would I track this every round?) Other better mathematical approaches?

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  • Difficulties with rotation of a sprite

    - by Andy
    I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. My dolphin always rests in the same angle while it jumps. But I want that it changes the rotation during the jump, like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation = 45; VelocityY += 40f; } else { rotation = -45; VelocityY += 40f; } } } else { VelocityY += -10f; } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, MathHelper.ToRadians(rotation), new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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  • how get collision callback of two specific objects using bullet physics?

    - by sebap123
    I have got problem implementing collision callback into my project. I would like to have detection between two specific objects. I have got normall collision but I want one object to stop or change color or whatever when colides with another. I wrote code from bullet wiki: int numManifolds = dynamicsWorld->getDispatcher()->getNumManifolds(); for (int i=0;i<numManifolds;i++) { btPersistentManifold* contactManifold = dynamicsWorld->getDispatcher()->getManifoldByIndexInternal(i); btCollisionObject* obA = static_cast<btCollisionObject*>(contactManifold->getBody0()); btCollisionObject* obB = static_cast<btCollisionObject*>(contactManifold->getBody1()); int numContacts = contactManifold->getNumContacts(); for (int j=0;j<numContacts;j++) { btManifoldPoint& pt = contactManifold->getContactPoint(j); if (pt.getDistance()<0.f) { const btVector3& ptA = pt.getPositionWorldOnA(); const btVector3& ptB = pt.getPositionWorldOnB(); const btVector3& normalOnB = pt.m_normalWorldOnB; bool x = (ContactProcessedCallback)(pt,fallRigidBody,earthRigidBody); if(x) printf("collision\n"); } } } where fallRigidBody is a dynamic body - a sphere and earthRigiBody is static body - StaticPlaneShape and sphere isn't touching earthRigidBody all the time. I have got also other objects that are colliding with sphere and it works fine. But the program detects collision all the time. It doesn't matter if the objects are or aren't colliding. I have also added after declarations of rigid body: earthRigidBody->setCollisionFlags(earthRigidBody->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK); fallRigidBody->setCollisionFlags(fallRigidBody->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK); So can someone tell me what I am doing wrong? Maybe it is something simple?

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  • Android Loading Screen: How do I go about using a stack to load elements, and the option of incrementing the size counter?

    - by tom_mai78101
    I have some problems with figuring out what value I should put in the function: int value_needed_to_figure_out = X; ProgressBar.incrementProgressBy(value_needed_to_figure_out); I've been researching about loading screens and how to use them. Some examples I've seen have implemented Thread.sleep() in a Handler.post(new Runnable()) function. To me, I got most of that concept of using the Handler to update the ProgressBar, while pretending to do some heavy crunching work. So, I kept looking. I have read this thread here: How do I load chunks of data from an assest manager during a loading screen? It said that I can try using a stack it needs to load, and adding a size counter as I add elements to the stack. What does it mean? This is the part where I'm totally stumped. If anyone would provide some hints, I'll gladly appreciate it. Thanks in advance.

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  • Rending 2D Tile World (With Player In The Middle)

    - by Mick
    What I have at the moment is a series of data structures I'm using, and I would like to render the world onto the screen (just the visible parts). I've actually already done this several times (lots of rewrites), but it's a bit buggy (rounding seems to make the screen jump ever so slightly every x tiles the player walks past). Basically I've been confusing myself heavily on what I feel should be a pretty simple problem... so here I am asking for some help! OK! So I have a 50x50 array holding the tiles of the world. I have the player position as 2 floats, x ([0, 49]) and y ([0, 49]) in that array. I have the application size exactly in pixels (x and y). I have an arbitrary TILE_SIZE static int (based on screen pixels). What I think is heavily confusing me is using a 2d orthogonal projection in opengl which maps (0,0) to the top left of the screen and (SCREEN_SIZE_X, SCREEN_SIZE_Y) to the bottom right of the screen. gl.glMatrixMode(GL.GL_PROJECTION); gl.glLoadIdentity(); glu.gluOrtho2D(0, getActualWidth(), getActualHeight(), 0); gl.glMatrixMode(GL.GL_MODELVIEW); gl.glLoadIdentity(); The map tiles are set so that the (0,0) in the array is the bottom left. And the player has to be in the middle on the screen (SCREEN_SIZE_X/2, SCREEN_SIZE_Y/2). What I've been doing so far is trying to render 1-2 tiles more all around what would be displayed on the screen so that I don't have to worry about figuring out rendering half a tile from the top left, depending where the player is. It seems like such an easy problem but after spending about 40+hours on it rewriting it many times I think I'm at a point where I just can't think clearly anymore... Any help would be appreciated. It would be great if someone can provide some very basic pseudo code on keeping the player in the middle when your projection is mapped to screen coordinates and only rendering basically the tiles that you would be any be see. Thanks!

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  • How do I interpolate air drag with a variable time step?

    - by Valentin Krummenacher
    So I have a little game which works with small steps, however those steps vary in time, so for example I sometimes have 10 Steps/second and then I have 20 Steps/second. This changes automatically depending on how many steps the user's computer can take. To avoid inaccurate positioning of the game's player object I use y=v0*dt+g*dt^2/2 to determine my objects y-position, where dt is the time since the last step, v0 is the velocity of my object in the beginning of my step and g is the gravity. To calculate the velocity in the end of a step I use v=v0+g*dt what also gives me correct results, independent of whether I use 2 steps with a dt of for example 20ms or one step with a dt of 40ms. Now I would like to introduce air drag. For simplicity's sake I use a=k*v^2 where a is the air drag's acceleration (I am aware that it would usually result in a force, but since I assume 1kg for my object's mass the force is the same as the resulting acceleration), k is a constant (in this case I'm using 0.001) and v is the speed. Now in an infinitely small time interval a is k multiplied by the velocity in this small time interval powered by 2. The problem is that v in the next time interval would depend on the drag of the last which again depends on the v of the last interval and so on... In other words: If I use a=k*v^2 I get different results for my position/velocity when I use 2 steps of 20ms than when I use one step of 40ms. I used to have this problem for my position too, but adding +g*dt^2/2 to the formula for my position fixed the problem since it takes into account that the position depends on the velocity which changes slightly in every infinitely small time interval. Does something like that exist for air drag too? And no, I dont mean anything like Adding air drag to a golf ball trajectory equation or similar, for that kind of method only gives correct results when all my steps are the same. (I hope you can understand my intermediate english, it's not my main language so I would like to say sorry for all the silly mistakes I might have made in my question)

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  • 2D mouse coordinates from 3d object projection

    - by user17753
    Not entirely certain of the nomenclature here -- basically, after placing a model in world coordinates and setting up a 3D camera to look at it the model has been projected onto the screen in a 2D fashion. What I'd like to do is determine if the mouse is inside the projected view of the model. Is there a way to "unproject" in the XNA framework? Or what is this process called as, so that I can better search for it?

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