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• 16-bit PNGs in Slick2D

  - by Neglected

  I'm working on a project and I'm using some 3rd party sprites just to get it off the ground; recently I've come into a hitch. Slick2D doesn't seem to want to load my images. That is, it will warn me that images are the wrong bit-depth. All the images are in 16-bit PNG form (PNG is required for transparency). Is there any way I can disable the warning (being the bad guy programmer (the console print for each individual load REALLY SLOWS DOWN the image)) or is there another solution? I was thinking about converting all images (using imagemagick) to .gif (with an alpha channel). Would there be any loss in quality between formats? EDIT: I tried using imagemagick but some of the sprites use pure black so I can't do that without wrecking the image. EDIT2: using "identify" on any of the images show them as being 8-bit.. but Slick2D won't load them. What the hell? D: EDIT3: Issue solved (ish). If you are googling this then just disable the java png loader from slick by sticking this somewhere in your code (like the main method): System.setProperty("org.newdawn.slick.pngloader", "false");

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• How does your team handle support requests

  - by Skeep

  Hi All, I have just taken over as manager at a company and at the moment they are very rigid in how they approach development. Everyone gets a list of what they are doing each week. My question is how does your company balance support with development and if an important support request comes in how is this processed without disturbing the flow of the developers? Lastly, do you use an software log support requests and development tasks. Thanks

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• How to avoid movement speed stacking when multiple keys are pressed?

  - by eren_tetik

  I've started a new game which requires no mouse, thus leaving the movement up to the keyboard. I have tried to incorporate 8 directions; up, left, right, up-right and so on. However when I press more than one arrow key, the movement speed stacks (http://gfycat.com/CircularBewitchedBarebirdbat). How could I counteract this? Here is relevant part of my code: var speed : int = 5; function Update () { if(Input.GetKey(KeyCode.UpArrow)){ transform.Translate(Vector3.forward * speed * Time.deltaTime); } else if(Input.GetKey(KeyCode.UpArrow) && Input.GetKey(KeyCode.RightArrow)){ transform.Translate(Vector3.forward * speed * Time.deltaTime); } else if(Input.GetKey(KeyCode.UpArrow) && Input.GetKey(KeyCode.LeftArrow)){ transform.rotation = Quaternion.AngleAxis(315, Vector3.up); } if(Input.GetKey(KeyCode.DownArrow)){ transform.Translate(Vector3.forward * speed * Time.deltaTime); } }

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• Drawing Transparency in XNA 4.0

  - by dpaz

  Using C# (VS2010) with XNA 4.0, I have a terrain layer (RenderTarget2D) in a 2D side-scroller. My visual system tracks updates to redraw individual tiles, but I am having trouble finding a way to clear out the rectangle where the tile will be drawn, which I must do because A) there may no longer be a tile or B) the tile may itself contain transparency. How can I draw a rectangle of transparency onto an existing RenderTarget2D? I essentially want to clear just that rectangular portion of it. My Google searches have not yielded anything relevant.

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• LibGDX onTouch() method kill on touch

  - by johnny-b

  How can I add this on my application. i want to use the onTouch() method from the implementation of the InputProcessor to kill the enemies on screen. how do i do that? do i have to do anything to the enemy class? please help Thank you M @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { return false; } here is my enemy class public class Bullet extends Sprite { private Vector2 velocity; private float lifetime; public Bullet(float x, float y) { velocity = new Vector2(0, 0); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); velocity.x += dx * delta; velocity.y += dy * delta; } } i am rendering all graphics in a GameRender class and a gameworld class if you need more info please let me know Thank you

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• Doing imagemagick like stuff in Unity (using a mask to edit a texture)

  - by Codejoy

  There is this tutorial in imagemagick http://www.imagemagick.org/Usage/masking/#masks I was wondering if there was some way to mimic the behavior (like cutting the image up based on a black image mask that turns image parts transparent... ) and then trim that image in game... trying to hack around with the webcam feature and reproduce some of the imagemagick opencv stuff in it in Unity but I am saddly unequipped with masks, shaders etc in unity skill/knowledge. Not even sure where to start.

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• Enemies don't shoot. What is wrong? [closed]

  - by Bryan

  I want that every enemy shoots independently bullets. If an enemy’s bullet left the screen, the enemy can shoot a new bullet. Not earlier. But for the moment, the enemies don't shoot. Not a single bullet. I guess their is something wrong with my Enemy class, but I can't find a bug and I get no error message. What is wrong? public class Map { Texture2D myEnemy, myBullet ; Player Player; List<Enemy> enemieslist = new List<Enemy>(); List<Bullet> bulletslist = new List<Bullet>(); float fNextEnemy = 0.0f; float fEnemyFreq = 3.0f; int fMaxEnemy = 3 ; Vector2 Startposition = new Vector2(200, 200); GraphicsDeviceManager graphicsDevice; public Map(GraphicsDeviceManager device) { graphicsDevice = device; } public void Load(ContentManager content) { myEnemy = content.Load<Texture2D>("enemy"); myBullet = content.Load<Texture2D>("bullet"); Player = new Player(graphicsDevice); Player.Load(content); } public void Update(GameTime gameTime) { Player.Update(gameTime); float delta = (float)gameTime.ElapsedGameTime.TotalSeconds; for(int i = enemieslist.Count - 1; i >= 0; i--) { // Update Enemy Enemy enemy = enemieslist[i]; enemy.Update(gameTime, this.graphicsDevice, Player.playershape.Position, delta); // Try to remove an enemy if (enemy.Remove == true) { enemieslist.Remove(enemy); enemy.Remove = false; } } this.fNextEnemy += delta; //New enemy if (fMaxEnemy > 0) { if ((this.fNextEnemy >= fEnemyFreq) && (enemieslist.Count < 3)) { Vector2 enemyDirection = Vector2.Normalize(Player.playershape.Position - Startposition) * 100f; enemieslist.Add(new Enemy(Startposition, enemyDirection, Player.playershape.Position)); fMaxEnemy -= 1; fNextEnemy -= fEnemyFreq; } } } public void Draw(SpriteBatch batch) { Player.Draw(batch); foreach (Enemy enemies in enemieslist) { enemies.Draw(batch, myEnemy); } foreach (Bullet bullets in bulletslist) { bullets.Draw(batch, myBullet); } } } public class Enemy { List<Bullet> bulletslist = new List<Bullet>(); private float nextShot = 0; private float shotFrequency = 2.0f; Vector2 vPos; Vector2 vMove; Vector2 vPlayer; public bool Remove; public bool Shot; public Enemy(Vector2 Pos, Vector2 Move, Vector2 Player) { this.vPos = Pos; this.vMove = Move; this.vPlayer = Player; this.Remove = false; this.Shot = false; } public void Update(GameTime gameTime, GraphicsDeviceManager graphics, Vector2 PlayerPos, float delta) { nextShot += delta; for (int i = bulletslist.Count - 1; i >= 0; i--) { // Update Bullet Bullet bullets = bulletslist[i]; bullets.Update(gameTime, graphics, delta); // Try to remove a bullet... Collision, hit, or outside screen. if (bullets.Remove == true) { bulletslist.Remove(bullets); bullets.Remove = false; } } if (nextShot >= shotFrequency) { this.Shot = true; nextShot -= shotFrequency; } // Does the enemy shot? if ((Shot == true) && (bulletslist.Count < 1)) // New bullet { Vector2 bulletDirection = Vector2.Normalize(PlayerPos - this.vPos) * 200f; bulletslist.Add(new Bullet(this.vPos, bulletDirection, PlayerPos)); Shot = false; } if (!Remove) { this.vMove = Vector2.Normalize(PlayerPos - this.vPos) * 100f; this.vPos += this.vMove * delta; if (this.vPos.X > graphics.PreferredBackBufferWidth + 1) { this.Remove = true; } else if (this.vPos.X < -20) { this.Remove = true; } if (this.vPos.Y > graphics.PreferredBackBufferHeight + 1) { this.Remove = true; } else if (this.vPos.Y < -20) { this.Remove = true; } } } public void Draw(SpriteBatch batch, Texture2D myTexture) { if (!Remove) { batch.Draw(myTexture, this.vPos, Color.White); } } } public class Bullet { Vector2 vPos; Vector2 vMove; Vector2 vPlayer; public bool Remove; public Bullet(Vector2 Pos, Vector2 Move, Vector2 Player) { this.Remove = false; this.vPos = Pos; this.vMove = Move; this.vPlayer = Player; } public void Update(GameTime gameTime, GraphicsDeviceManager graphics, float delta) { if (!Remove) { this.vPos += this.vMove * delta; if (this.vPos.X > graphics.PreferredBackBufferWidth +1) { this.Remove = true; } else if (this.vPos.X < -20) { this.Remove = true; } if (this.vPos.Y > graphics.PreferredBackBufferHeight +1) { this.Remove = true; } else if (this.vPos.Y < -20) { this.Remove = true; } } } public void Draw(SpriteBatch spriteBatch, Texture2D myTexture) { if (!Remove) { spriteBatch.Draw(myTexture, this.vPos, Color.White); } } }

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• When attaching AI to a vehicle should I define all steps or try Line of Sight?

  - by ThorDivDev

  This problem is related to an intersection simulation I am building for university. I will try to make it as general as possible. I am trying to assign AI to a vehicle using the JMonkeyEngine platform. AIGama_JmonkeyEngine explains that if you wish to create a car that follows a path you can define the path in steps. If there was no physics attached whatsoever then all you need to do is define the x,y,z values of where you want the object to appear in all subsequent steps. I am attaching the vehicleControl that implements jBullet. In this case the author mentions that I would need to define the steering and accelerating behaviors at each step. I was trying to use ghost controls that represented waypoints and when on colliding the car would decide what to do next like stopping at a red light. This didn't work so well. Car doesn't face right. public void update(float tpf) { Vector3f currentPos = aiVehicle.getPhysicsLocation(); Vector3f baseforwardVector = currentPos.clone(); Vector3f forwardVector; Vector3f subsVector; if (currentState == ObjectState.Running) { aiVehicle.accelerate(-800); } else if (currentState == ObjectState.Seeking) { baseforwardVector = baseforwardVector.normalize(); forwardVector = aiVehicle.getForwardVector(baseforwardVector); subsVector = pointToSeek.subtract(currentPos.clone()); System.out.printf("baseforwardVector: %f, %f, %f\n", baseforwardVector.x, baseforwardVector.y, baseforwardVector.z); System.out.printf("subsVector: %f, %f, %f\n", subsVector.x, subsVector.y, subsVector.z); System.out.printf("ForwardVector: %f, %f, %f\n", forwardVector.x, forwardVector.y, forwardVector.z); if (pointToSeek != null && pointToSeek.x + 3 >= currentPos.x && pointToSeek.x - 3 <= currentPos.x) { aiVehicle.steer(0.0f); aiVehicle.accelerate(-40); } else if (pointToSeek != null && pointToSeek.x > currentPos.x) { aiVehicle.steer(-0.5f); aiVehicle.accelerate(-40); } else if (pointToSeek != null && pointToSeek.x < currentPos.x) { aiVehicle.steer(0.5f); aiVehicle.accelerate(-40); } } else if (currentState == ObjectState.Stopped) { aiVehicle.accelerate(0); aiVehicle.brake(40); } }

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• How to setup my texture cordinates correctly in GLSL 150 and OpenGL 3.3?

  - by RubyKing

  I'm trying to do texture mapping in GLSL 150 and OpenGL 3.3 Here are my shaders I've tried my best to get this correct as possible hopefully this is :) I'm guessing you want to know what the problem is well my texture shows but not in its fullest form just one section of it not the full texture on the quad. All I can think of is its the texture cordinates in the main.cpp which is at the bottom of this post. FRAGMENT SHADER #version 150 in vec2 Texcoord_VSPS; out vec4 color; // Values that stay constant for the whole mesh. uniform sampler2D myTextureSampler; //Main Entry Point void main() { // Output color = color of the texture at the specified UV color = texture2D( myTextureSampler, Texcoord_VSPS ); } VERTEX SHADER #version 150 //Position Container in vec3 position; //Container for TexCoords attribute vec2 Texcoord0; out vec2 Texcoord_VSPS; //out vec2 ex_texcoord; //TO USE A DIFFERENT COORDINATE SYSTEM JUST MULTIPLY THE MATRIX YOU WANT //Main Entry Point void main() { //Translations and w Cordinates stuff gl_Position = vec4(position.xyz, 1.0); Texcoord_VSPS = Texcoord0; } LINK TO MAIN.CPP http://pastebin.com/t7Vg9L0k

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• What is causing this behavior with the movement of Pong Ball in 2D? [closed]

  - by thegermanpole

  //edit after running it through the debugger it turned out i had the display function set to x,x...TIL how to use a debugger I've been trying to teach myself C++ SDL with the lazyfoo tutorial and seem to have run into a roadblock. The code below is the movement function of my Dot class, which controls the ball. The ball seems to ignore yvel and moves with xvel to the bottom right. The code should be pretty readable, the rest of the relevant facts are: All variables are names Constants are in caps dotrad is the radius of my dot yvel and xvel are set to 5 in the constructor The dot is created at x and y equal to 100 When I comment out the x movement block it doesn't move, but if i comment out the y movement block, it keeps on going down to the right. void Dot::move() { if(((y+yvel+dotrad) <= SCREEN_HEIGHT) && (0 <= (y-dotrad+yvel))) { y+=yvel; } else { yvel = -1*yvel; } if(((x+xvel+dotrad) <= SCREEN_WIDTH) && (0 <= (x-dotrad+xvel))) { x +=xvel; } else { xvel = -1*xvel; } }

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• Parsing glGetShaderInfoLog() to get error info. Is this reliable, or is there a better way?

  - by m4ttbush

  I want to get a list of errors and their line numbers so I can display the error information different to how it's formatted in the error string, and also show the line in error. It looks easy enough to just parse the result of glGetShaderInfoLog(), look for "ERROR:" then read the next number up to : and then the next, and then the error description up to the next newline. But the OpenGL docs say "Application developers should not expect different OpenGL implementations to produce identical information logs." Which makes me worry that my code may behave incorrectly on different systems. I don't need them to be identical, I just need them to follow the same format. So is there a better way to get a list of errors with line number separate, is it safe to assume that they'll always follow the "ERROR: 0:123:" format, or is there simply no reliable way to do this? Thanks!

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• Building an instance system.

  - by Kyle C

  I am looking into how to design an instance system for the game I am working on. I have always wondered how these are created in games like World of Warcraft, where instances == dungeons/raids/etc). Areas that are separated from players other than those in your group, but have specific logic to them. Specifically how can you reuse your existing code base and not have a bunch of checks everywhere ? if (isInstance) do x; else do y; I don't know if this will make too much of a difference on any answers, but we're using a pretty classic "Object as pure aggregation" component system for our entities.

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• How to disguise a serverside mob as another?

  - by Shaun Wild

  I've been working a Minecraft sever mod and i want to be able to add a new entity to the server, but then make the server send the packets to the client, imitating another mob, for example.. Lets say say i have EntityPlayerNPC.class, what i want to do is have all of the packets that get sent to the client look like they are from that of another player which is on the player, therefore allowing me to add custom NPC's... Thinking about the theory i'm sure this can be done. I've tried looking around for where the packets are being sent from and whatnot, can anyone think up a solution? edit: i tried adding a new constructor to the Packet20NamedEntitySpawn class like so: public Packet20NamedEntitySpawn(String username, EntityLiving e){ this.entityId = 0; this.name = username; this.xPosition = MathHelper.floor_double(e.posX * 32.0D); this.yPosition = MathHelper.floor_double(e.posY * 32.0D); this.zPosition = MathHelper.floor_double(e.posZ * 32.0D); this.rotation = (byte)((int)(e.rotationYaw * 256.0F / 360.0F)); this.pitch = (byte)((int)(e.rotationPitch * 256.0F / 360.0F)); this.metadata = e.getDataWatcher(); } unfortunatley, that didn't work :(

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• How to populate a form list with buttons using javascript

  - by StealingMana

  I made a script that, when you press one button(accessories) the selection(mylist) populates with one array(accessoryData), and when you hit the other button(weapons) the other array(weaponData) populates the selection. However, in the current state of the code the second button press is not re-populating the selection. What is wrong here? Also if there is a more efficient way to do this, that might be helpful. Full code function runList(form, test) { var html = ""; var x; dataType(test); while (x < dataType.length) { html += "<option>" + dataType[x]; x++; } document.getElementById("mylist").innerHTML = html; }

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• Observer Pattern Implementation

  - by user17028

  To teach myself basic game programming, I am going to program a clone of Pong. I will use the Observer design pattern, with an interface between the input and the game engine. However, I'm not sure what the interface should do. One idea I had was for the input interface to tell the game engine that (e.g.) the screen was clicked, then to let the game engine decide what to do with that information (shoot a bullet, for example). Another idea I had was for the input interface, having caught the mouse click, to tell the game engine to shoot a bullet. Which method would be better for me to use?

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• Unity3D 3.5 pro - Moving the camera vs setting draw distance

  - by stoicfury

  I move the camera mostly via right-click + WASD, sometimes with [shift] if I want it to move faster. Occasionally, instead of moving my camera, it alters the draw distance / FOV / some visual aspect of the editing scene that causes trees and other object to disappear when I scroll enough, and eventually even the terrain starts disappearing. It is not m "zooming out". My camera does not move, the width and height of the FOV stays the same (one might say the depth is being altered though). What key am I hitting to cause this to happen, and is it possible to disable it? side note: "keybinds" is probably the most spot-on tag for this question but it doesn't exist (surprisingly) and I lack the rep to create it.

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• Game planning and software design? I feel that UML is not convenient

  - by user1542

  In my university, they always emphasize and hype about UML design and stuff, in which I feel it is not going to work well with game structure design. Now, I just want a professional advice on how should I begin my game designing? The story is I have some skill in programming and have done many minor game such as getting some 2D platformer working to some extend. The problems that I find about my program is the poor quality design. After coding for a while, things start to break down due to poor planning (When I add new feature, it tends to make me have to recode the whole program). However, to plan everything out without a single design flaw is a bit too ideal. Therefore, any advice to how should I plan my game? How should I put it into visible pictures, so that me and my friends are able to overview the designs? I planned to start coding a game with my friend. This is going to be my first teamwork, so any professional advices would be a pleasure. Is there any other alternatives than UML? Another question is how does "prototyping" normally looks like?

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• Making a Living Developing Games

  - by cable729

  I'm in my last year of high school, and I've been looking at colleges. I'm taking a C++ class at a local community college and I don't feel that it's worth it. I could have learned everything in that class in a week. This had me thinking, would a CS degree even be worth it? How much can it teach me if I can learn everything on my own? Even if I do need to learn more advanced subjects, many colleges put their material online AND I can buy a book. Will companies hire me if I don't have a CS degree? If I have a portfolio will I stand a chance? What kind of things are needed in the portfolio? I want to live doing what I love - programming. So I will do it. I'm just not sure that a CS degree will do anything to me. In addition, if there is a benefit to getting a CS degree, what places are the best?

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• Multiple Kickstarter campaigns. Good? Bad? Ugly?

  - by BerickCook

  I've been toying with the idea of doing a Kickstarter for my game to help fund some good artists to replace the placeholder graphics I currently have. Just a small goal of $2k or so. Regardless of whether the campaign is successful this time, would it be considered a faux pas to do another, larger kickstarter once the game is looking better? Would the rewards need to be the same, or could I offer better rewards at lower donation levels for the first one as an "early adopter" bonus?

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• How to avoid the GameManager god object?

  - by lorancou

  I just read an answer to a question about structuring game code. It made me wonder about the ubiquitous GameManager class, and how it often becomes an issue in a production environment. Let me describe this. First, there's prototyping. Nobody cares about writing great code, we just try to get something running to see if the gameplay adds up. Then there's a greenlight, and in an effort to clean things up, somebody writes a GameManager. Probably to hold a bunch of GameStates, maybe to store a few GameObjects, nothing big, really. A cute, little, manager. In the peaceful realm of pre-production, the game is shaping up nicely. Coders have proper nights of sleep and plenty of ideas to architecture the thing with Great Design Patterns. Then production starts and soon, of course, there is crunch time. Balanced diet is long gone, the bug tracker is cracking with issues, people are stressed and the game has to be released yesterday. At that point, usually, the GameManager is a real big mess (to stay polite). The reason for that is simple. After all, when writing a game, well... all the source code is actually here to manage the game. It's easy to just add this little extra feature or bugfix in the GameManager, where everything else is already stored anyway. When time becomes an issue, no way to write a separate class, or to split this giant manager into sub-managers. Of course this is a classical anti-pattern: the god object. It's a bad thing, a pain to merge, a pain to maintain, a pain to understand, a pain to transform. What would you suggest to prevent this from happening?

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• How should game objects be aware of each other?

  - by Jefffrey

  I find it hard to find a way to organize game objects so that they are polymorphic but at the same time not polymorphic. Here's an example: assuming that we want all our objects to update() and draw(). In order to do that we need to define a base class GameObject which have those two virtual pure methods and let polymorphism kicks in: class World { private: std::vector<GameObject*> objects; public: // ... update() { for (auto& o : objects) o->update(); for (auto& o : objects) o->draw(window); } }; The update method is supposed to take care of whatever state the specific class object needs to update. The fact is that each objects needs to know about the world around them. For example: A mine needs to know if someone is colliding with it A soldier should know if another team's soldier is in proximity A zombie should know where the closest brain, within a radius, is For passive interactions (like the first one) I was thinking that the collision detection could delegate what to do in specific cases of collisions to the object itself with a on_collide(GameObject*). Most of the the other informations (like the other two examples) could just be queried by the game world passed to the update method. Now the world does not distinguish objects based on their type (it stores all object in a single polymorphic container), so what in fact it will return with an ideal world.entities_in(center, radius) is a container of GameObject*. But of course the soldier does not want to attack other soldiers from his team and a zombie doesn't case about other zombies. So we need to distinguish the behavior. A solution could be the following: void TeamASoldier::update(const World& world) { auto list = world.entities_in(position, eye_sight); for (const auto& e : list) if (auto enemy = dynamic_cast<TeamBSoldier*>(e)) // shoot towards enemy } void Zombie::update(const World& world) { auto list = world.entities_in(position, eye_sight); for (const auto& e : list) if (auto enemy = dynamic_cast<Human*>(e)) // go and eat brain } but of course the number of dynamic_cast<> per frame could be horribly high, and we all know how slow dynamic_cast can be. The same problem also applies to the on_collide(GameObject*) delegate that we discussed earlier. So what it the ideal way to organize the code so that objects can be aware of other objects and be able to ignore them or take actions based on their type?

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• How do you deal with transitions in animating walking?

  - by Aerovistae

  I'm pretty new to this whole animating models thing. Just learning the ropes. I got a nice walking animation going, which I can loop while a character is walking, but what about when they stop walking? I mean, they could be at any point in the animation at the time the player stops walking. How do I get them to smoothly return to a standing still position without having them snap into that position? The same goes for starting walking from a standing still position. Do you need a separate animation? How is this dealt with?

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• How does N create it's tileset?

  - by Darestium

  I am trying to recreate a Multiplayer version of the popular flash game N in java. I have a single question however. Are the tiles for the games draw or are they defined with mathamatical formulars/In code? Since I do see how they would scale up in flash if they were not. So if anyone has any ideas how I should go about creating the tileset, or how they are created in the game please let me know. You can check out the game here.

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• How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

  - by Register Sole

  Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they would swing! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :) EDIT In response to Cholesky's comment about warm starting the solver and Baumgarte: Oh right, I forgot to mention! I do save the contact history and the impulse determined in this time step to be used as initial guess in the next time step. As for the Baumgarte, here's what actually happens in the code. Collision is detected when the bodies' closest distance is less than SKIN, meaning they are actually still separated. If at this moment, I used the PGS solver without Baumgarte, restitution of 0 alone would be able to stop the bodies, separated by a distance of ~SKIN, in mid-air! So this isn't right, I want to have the bodies touching each other. So I turn on the Baumgarte, where its role is actually to pull the bodies together! Weird I know, a scheme intended to push the body apart becomes useful for the reverse. Also, I found that if I increase the number of iteration to 100, stacks become much more stable, though the program becomes so slow. UPDATE Since the stack swings left and right, could it be something is wrong with my friction model? Current friction constraint: relative_tangential_velocity = 0

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• Dropping multiple objects using an array in Actionscript?

  - by Eratosthenes

  I'm trying to get these fireBalls to drop more often, I'm not sure if I'm using Math.random correctly. Also, for some reason I'm getting a null reference because I think the fireBalls array waits for one to leave the stage before dropping another one? This is the relevant code: var sun:Sun=new Sun var fireBalls:Array=new Array() var left:Boolean; function onEnterFrame(event:Event){ if (left) { sun.x = sun.x - 15; }else{ sun.x = sun.x + 15; } if (fireBalls.length>0&&fireBalls[0].y>stage.stageHeight){ // Fireballs exit stage removeChild(fireBalls[0]); fireBalls.shift(); } for (var j:int=0; j<fireBalls.length; j++){ fireBalls[j].y=fireBalls[j].y+15; if (fireBalls[j].y>stage.stageHeight-fireBall.width/2){ } } if (Math.random()<.2){ // Fireballs shooting from Sun var fireBall:FireBall=new FireBall; fireBall.x=sun.x; addChild(fireBall); fireBalls.push(fireBall); } }

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