Update Pack 1: Multiplayer 1.0

Tuesday, July 16, 2019

I’ve been kind of busy lately, so I haven’t posted an update or uploaded my progress to GitHub in a while, but I’ve gotten a good amount of work done. In fact, this package of updates contains the FIRST instance of what could actually be considered a multiplayer game! As of now, there is little to do besides walk around on a tiny map and see other players who are also connected, but getting the rendering of other players done was an obstacle that, once cleared, allowed me to bring this world to life. I never even reached this point when I was doing my game in Java, so it was fun brainstorming concepts to support a dynamic multiplayer world and then coding them into the real thing.

Multiplayer Support

– store online players in a hash table with their current map section as the key and their player ID as the value

– server ability to tell other clients about the existence and location of your player

– client ability to request the server to send info of all players in current map section

– requested when your player logs in

– requested when your player enters a new map section

– server sends all players in your map section an update on your coordinates whenever you send a movement request

– client support for rendering other players when receiving a notification of their existence from the server

– your player has a different appearance than all other players on your client

– server ability to tell other clients about the “absence” of your player

– clients respond to player absence notifications by no longer rendering that player

– absence notifications are sent to everyone in a map section when a player leaves that sesction

– absence notifications are sent when a player disconnects from the server

– players are removed from the global hash table when disconnecting

– clear data of players to be rendered on the client when entering a new map section

– this fixed a bug where players from old map sections would still be rendered in your new area, even though they weren’t actually there

Data Structures:

– wrote my own hash table for processsing data

– added ability to store duplicate keys in the hash table

– added ability to remove specific (key,value) pairs from the hash table

– wrote my own “mutable list”

– mutable list starts at a set “small” size and resizes when it becomes full

~ resizing is not currently implemented, so it’s just a list that can hold 20 elements

– ability to iterate thru the items of a mutable list

Maps:

– added loading tiles from image files

– added cache of loaded tile images to be re-used in rendering instead of loading an image each time it needs to be rendered

– tile image files are named using base-36 numbers

– map is organized into “sections”, each of which is represented by a “map string” that is stored in data files on the server-side

– map section is an integer computed from player’s absolute coordinates

– server retrieves data from the file of the associated map section and sends the map string to the client

– client ability to process and render the map from its current map string

– client sends server a request for map data whenever it needs to refresh the map

– when logging in

– when moving off-screen into a new map section

– sections with no map data render as an astral “void” of starry sky

– ability to recognize tiles as walkable or unwalkable

~ will reform this to a more efficient method in the future

– prevented walking into unwalkable tiles

Misc:

– remove players from the game when their respective client disconnects from the server

– resulted in an accurate player count

– added mutex for thread-control in the game thread of the server

– this fixed a server-side segmentation fault when dealing with hashing players into their map sections, resulting in a much stabler server

– fixed a rare server issue that occasionally added random characters to the end of a player’s username, resulting in the server crashing when trying to find the respective player data file

Current To-Do List:

– add more chars to keyboard in client

– recycle old player ids

– support to kick clients from server-side

– stop messages from being processed from kicked players

– prevent login if player is already logged in (lol)

– issues logging out that can cause client to crash

– readme for how to run

– organize and document code

– make the map move around the player

– reduce cpu usage

– bugs causing the client to crash (these happen randomly)

– using the logout button sometimes triggers a segmentation fualt

– entering the game sometimes triggers a segmentation fault

~ most likely needs a mutex to fix

– improve the loaded tile image cache mechanics

– right now it will fail if the cache gets full

– need to add tile “unloading”

– perhaps a splay tree would be useful for this

– add the resizing mechanic to mutable lists

Update Pack 2: User Interface, Map Building, Chat

Updates (expand)

Thursday, August 1, 2019

I actually finished 90% of this update pack shortly after I released my first update pack, but I stalled a lot getting the remaining details finished. Anyway, this update pack brings some features that make the game feel just a little bit more like an actual game. The main three features I’ve added are user interfaces, an in-game map editor, and public chat. Here is a video demonstrating these:

Below is a mostly-complete list of updates that went into this update pack. I didn’t add exact dates because I forgot to write most of this down as I was doing it, so this list was mainly constructed from my own memory.

Changes Since Previous Update Pack:

– Sidebar Interfaces

drew icons for each “tab” of the interface
added the settings tab
displays button to toggle map editing
added logout tab which instantly logs you out when clicked

– Control Panel Interface

displays various option buttons when you may need them

– Info Box Interface

displays text notifications in-game
server-side support for sending a message to the player’s info box
info box messages are pushed upward on-screen so that newest messages are listed at the bottom

– In-Game Map Builder

added map editor state to control panel
added “toggle map editor” button to settings menu
added button to look up tile data
enter base-36 number for the tile you wish to add
click on a tile on the map to replace it with your selected tile
image of the chosen tile follows your cursor
support for click and drag for faster map drawing
added button to send map to server
- this updates the map data on the server to what you created in map editor mode

– Public Chat

added text field to client game state that appends text when typing
press enter to send your current text field as a public chat
public chat sends to server, then is broadcasted to all players in your map section
when client is notified of a player’s public chat, the message is displayed to the info box

– Sprite Cache for Client

attempts to load all sprites into one place, then use them as needed
- this seems to fix an occasional issue where an image is loaded and its pixels are completely screwed up

– Miscellaneous

fixed a client crash on login by properly initializing the client’s mapstring

To-Do List Relevant to Update Pack 2:

– Map

map stops loading correctly when entering negative coordinates
client segmentation fault occurs when trying to log in at the lowest positive-coordinate map section when other players are in the same section

– Menu Interface

add player info menu
- display player’s coordinates
- display player’s account status (player, developer, owner, etc.)
add logout menu
- “Thanks for playing” message
- button to log out (instead of instantly logging out when trying to open the logout menu)