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• ### Similar Content

• Get the code HERE.
This project is a nod to those 1990 pocket games that were all the rage in the day. The eTamagotchi features P2P networking showcasing how you can have a single application be both the client and the server at runtime. It features a random digimon (digital monster) that keeps track of all battles it has. The code is meant for demonstration and learning purposes only. The README lists each point that can be improved upon including gameplay mechanics.

• By crmbzy
I'm using artemis-odb for my prototype. I have managed to get the "KryoArtemisSerializer" to work and serialize my world (or just a few selected entities). I now want to transmit this data to another peer (I am doing this with Kryonet). The de-serialize is working, the only problem I ran into is, that I can't seem to tell the "WorldSerializationManager" to update my entities instead of always creating them.
I use
world.getSystem(WorldSerializationManager.class).load(inputstream, SaveFileFormat.class); to load the data from my byte input stream that was created by Kryo. Is there another way to de-serialize the entities and process them manually?!
Any insights highly appreciated!!
• By EddieK
Hi, so I'm trying to pack 4 color values into a single 32-bit float but I'm having some issues. The resulting color values which I am getting are not correct. What could be wrong here?
This is the part of code where I pack the 4 bytes into a single float in Java
byte [] colorBytes = new byte[4]; colorBytes[0] = (byte)(color.x*256); colorBytes[1] = (byte)(color.y*256); colorBytes[2] = (byte)(color.z*256); colorBytes[3] = (byte)(color.w*256); vertexManager.appendVertexColorData(ByteBuffer.wrap(colorBytes).order(ByteOrder.LITTLE_ENDIAN).getFloat()); I also tried this:
bitSh.x = 1.0f/(256.0f*256.0f*256.0f); bitSh.y = 1.0f/(256.0f*256.0f); bitSh.z = 1.0f/(256.0f); bitSh.w = 1.0f; color.x = object.vertexColorData[i*4+0]*r; color.y = object.vertexColorData[i*4+1]*g; color.z = object.vertexColorData[i*4+2]*b; color.w = object.vertexColorData[i*4+3]*a; vertexManager.appendVertexColorData(color.dot(bitSh)); But it didn't work either, though it gave me different results, both are incorrect.
uniform mat4 MVPMatrix; // model-view-projection matrix attribute vec4 position; attribute vec2 textureCoords; attribute float color; varying vec4 outColor; varying vec2 outTexCoords; const vec4 bitSh = vec4(256.0*256.0*256.0, 256.0*256.0, 256.0, 1.0); const vec4 bitMsk = vec4(0.0, 1.0/256.0, 1.0/256.0, 1.0/256.0); vec4 unpack_float(const float value) { vec4 res = fract(value * bitSh); res -= res.xxyz * bitMsk; return res; } void main() { outTexCoords = textureCoords; outColor = unpack_float(color); gl_Position = MVPMatrix * position; }
And this is the fragment shader:
precision lowp float; uniform sampler2D texture; varying vec4 outColor; varying vec2 outTexCoords; varying vec3 outNormal; void main() { gl_FragColor = texture2D(texture, outTexCoords) * outColor; }

• Hello, my name is Jamal and I've been interested in programming video games for a long time. I've attempted to make games in the past however, they never really got far or at least close enough to them being released. This is mainly because I was biting off more than I could chew. I know that before I ask this question, many people are going to discourage me from making an MMO. Please save those comments because I know exactly how hard it is to make an MMO. Which is why I am starting off small and then working towards making my game greater.

Anyhow, I plan on releasing a 2D Java game that is going to be hosted on my websites server. I wanted to make the game multiplayer(obviously) but I also wanted to make a system in which the player would log-in and then be able to access their characters in their account and play the story. I'm recently learning about sockets however, I was wondering if anyone had a method or even the slightest idea of how to save a player's information so that it could be loaded back into the game?
I already have an idea where whenever the player logs in, you create a new initiate of a Player Object and then pass certain variables through. For example, the player logs in from one GameState and then goes into another GameState in which the Player() is called. When the Player() is called, it passes these values and these values tell the game where the player needs to be, etc.
public class Player { String name; String race; int attack; int defense; public Player(String name, String race, int attack, int defense) { this.name = name; this.race = race; this.attack = attack; this.defense = defense; //etc } } I could always store these values into a SQL database so that way whenever the player logs in, I can just pull these values from there however, I was wondering if there was a better method for saving the player's data. Any thoughts?
• By EddieK
Hi, so I have this game which I'm working on and I have implemented A* pathfinding algorithm, but the problem is that the game framerate drops significantly if there are more than 50-100 enemies which need to find path to player.
I did some code analyzing and noticed that the part which takes longest to process is part where it searches for node with the lowest F score. Is there anyway I could speed the process up?
Here's the code I'm using:
public ArrayList<Node> getPath(Node start, Node end){ closedSet.clear(); openSet.clear(); openSet.add(start); cameFrom.clear(); start.gScore = 0; start.fScore = heuristicCostEstimate(start, end); while(openSet.size() > 0){ Node currentNode = lowestFScoreNode(openSet);//openSet.findLowestFScoreNode(); if(currentNode.equals(end)){ return reconstructPath(cameFrom, currentNode); } openSet.remove(currentNode); closedSet.add(currentNode); Node [] neighbours = getNeighbours(currentNode); for(int i = 0; i < neighboursCount; i++){ if(closedSet.contains(neighbours[i])) continue; openSet.add(neighbours[i]); float tentativeGScore = currentNode.gScore + heuristicCostEstimate(start, neighbours[i]); if(tentativeGScore >= neighbours[i].gScore) continue; cameFrom.put(neighbours[i], currentNode); neighbours[i].gScore = tentativeGScore; neighbours[i].fScore = neighbours[i].gScore + heuristicCostEstimate(neighbours[i], end); } } return null; } The lowestFScore node function just returns result of Collections.min()

# Error Handling Question

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Hi guys,

So I'm looking at another developers project for learning purposes and I'm just moving through the code so I can get an understanding of what's happening and how to write my own version of it. And the first thing I'm looking at is the 'try ..catch' statement. From what I can tell the purpose of try catch is to try a block of code and if an exception occurs then catch it, In this example I'm not sure how catching is actually working.

try {
} catch (InterruptedException e) {
}

I've also seen some basic examples where 0 is divided by a value and it's suppose to throw an Exception, the person then draws a line to say hey you can't divide like that. But in this case what will happen ?

I think more importantly, if an error occurs, does the program crash, and whether or not it crashes will I see a message in Eclipse console telling me what caused the error ?

And then, from what I've read some peoples approach is to determine what exceptions/errors may occur and then change their code to prevent that from happening.

These questions will help me understand whether or not I can take the following approach, code, run the program, attempt all possible interactions, when an error occurs see what it says in the console or rather see what interaction I did that caused it then modify the code to prevent that from happening, instead of catching exceptions.

Update:

I looked up exceptions a bit, I see that InterruptedException is a specific exception that throws when a sleeping thread is interrupted using the interrupt(); method. And that I don't see interrupt being used in the project then the exception is actually not required.

Edited by Xer0botXer0
Update

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Your question seems to be a little broad. Exception in general are when the program/computer encounters a situation that it does not know how to handle ie. dividing by 0. in this case, an Exception object is created and "thrown" to an Exception handler. if no exception handler is found within the program the program will exit(crash). when Designing a system a good programmer will anticipate when an exception will occur and reroute the program to prevent a crash. its important to realize that there are two types of exceptions. checked and unchecked. check exceptions are caused by programmer error and are caught by the interpreter/compiler. these types of exceptions will prevent a program from compiling. the second, uncheck, is also called a runtime error/exception. these are caused by the user giving an input that was unexpected or that the program does not know how to handle. these types are Not inherently bad. the one you are looking at may be a little confusing if you don't understand threads and concurrency. In this case the programmer has commanded a thread to wait/sleep for a certain amount of time. If in the event that some outside force like the OS, or even the user interrupts this thread it will throw an exception which the programmer can use to know that his thread is no longer sleeping. other examples of exception that are not necessarily bad; a FileNotFoundException can be used to check for the existence of a file before writing to it. after the programmer catches this exception he may, for example, prompt the user to create a new file before writing.

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"In this example I'm not sure how catching is actually working." - In this example the catch doesn't have to do anything. It is just there so that the exception is handled and doesn't propagate down to the caller. Exceptions that don't get handled cause the program to terminate. So when you write code that calls a function, you need to consider whether it can throw exceptions that you need to handle - like the writer of this code did, knowing that Thread.sleep can throw InterruptedException. Note that exceptions aren't always errors, such as in this case. It's just an unusual condition that needs handling.

If you can modify code to prevent the possibillity of certain exceptions being raised, that is usually preferable. But exceptions exist to handle conditions that you can't prevent, or events that you couldn't easily predict.

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Do I need to use "throws xException" in a method name, because I don't always see it used even though a try catch is used in the method ?

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In Java it's useful to have that there as it forces you to write good code. If you have "throws xException" then you're not allowed to let other exceptions be thrown out of the function - which is good news for callers of that function, as they know they only ever have to handle xExceptions. This is entirely about which exceptions can be thrown out of the method - it has no relation to try/catch blocks inside the method. However, you may need to add catch blocks in order to conform to the exception specification, as you will need to handle all other exceptions.