WebTTD – A Browser-based Transport Tycoon Derivate

2012-12-13

WebTTD – A Browser-based Transport Tycoon Derivate

I've a fixed idea of creating a web version of Transport Tycoon.

Imagine how wonderful it would be if you could build your company for several weeks or months, on a vast landscape. No hush-hush game like classical TTD, but rather slow progress, more business cooperation amongst players…

Game concept

Web game concepts are different from those of desktop games. If you ever have played Travian, you know how such web game works.

1) First, the game progress must be veeery sloooow. Why? Because web games are played occassionally – during a boring meetings, during launch break, before bed… People want to spend few minutes daily on such game. What can you do in that time? Build a track or two, buy a train and set their orders. Then you leave it until the next day. The train should do no more than few turns in that time.

2) Second, there are many many players, which join the game at different times. By the time you have been playing for several weeks, someone other joins the game; so you have your logistic imperium with dozens of tracks, and the other player has nothing but a loan. I've been thinking about this a lot, and came up with a solution similar to Travian's one.

3) Third, web games are not fun because of fancy graphics; But even not because of complicated game logic. The best part of MMO games are – the other players! Yes, it's the social part of the game which keeps people playing: The feel of being a part of gang.

This aspect would have to be carefully applied in the game design. Again, I have ideas about how to achieve that: In classical TTD, you always found point A, point B and built a track between them. Sometimes you found out that it's impossible because some area is being blocked by other player.

Well, in MMO-TTD, this would inevitably happen all the time, so it's not a good concept at all. Better would be to let people deal at which price can one player use other's track.

There are other things to think about, but these three are the main to focus at.

Technology

It would be programmed using technologies:

* HTML + CSS, eventually Canvas
* JavaScript for client logic
* J2EE backend with JBoss Cache,
* or perhaps thin PHP layer with stored procedures in PostgreSQL or MySQL

So far, I gave it about two days of work and have some poor proofs-of-concept:

1) TTD-like dialogs made in HTML. Currently only layout + some DoJo code to make them move.
This part would need a lot of work: many dialog types + data binding.
See the demo .
(Note that the dialogs are not images, but only HTML+CSS – see the page code.)

2) Isometric landscape drawing and editing, plus client/server communication (AJAX).
I'll add URL of this drawing as soon as I put the database on the server.
Works quite fine, but there's one big problem: When you click somewhere,
it's almost impossible to compute which cell has been clicked, so it's needed to store it somewhere.
And since current technologies, including canvas, do not provide such functionality,
the only solution seems to use only flat landscape, which is kinda boring…

Or, the other option – create the client in .NET or Java or Flash.
Since I don't like Flash and .NET is bound to Microsoft, it would be Java's WebStart.

Next I'd move to drawing of vehicles. That should be quite easy, provided we had waypoints of their movement together with their times.

These data have to be computed on the server side. So next stage would be J2EE or PL/SQL programming ~~(I'm SQL fan, so it's likely to be PL/SQL :)~~ //Decision changed:// Due to performance requirements, reading everything to and from the DB is not a good idea. Let it be Java.

Then the data are needed to be send to the client somehow, so some AJAX-Push would be necessary.

Of course the client will not load all the updates, only those which currently affect him – that means:

Only cells in his viewport
Only messages he configured to get
Vehicles positions are only send when it departs onto a track
No metrics of stations, towns, industries, companies – that's only on-demand in a dialog.

Estimated data transfer amounts is hundreds of bytes per second, at most.

Current code structure

Client side

Xcom – the main class / namespace (yeah, originally it should have been UFO ;)
- Xcom.Land – the class which manages the map data.
- Xcom.data: {
  - cities: []
  - industries: []
  - roadTracks: []
  - roadVehicles: []
  - companies: []
  - stations: []
- }
eMap – manages the DHTML representation of the land.
- eMap.TransformFieldXYtoCoords( x, y, level ) – computes mapbox coords of the given cell, taking the map offset into account.
- eMap.TransformCoordsToFieldXY( x, y ) – computes position of the cell on the given coordinates, taking the map offset into account.
- eMap.DrawArea( x1, y1, x2, y2 );
z-indexes:
- #map:
- #mapbox:
- #overlay:
- individual cells:

Server side

Game game
- TtdGrid land – auto-expanding grid of cells.
  - Currently organized to tiles with 10×10 cells – for optimization.
  - Cell get( x, y )
  - init(), run(), pause(), stop()
  - persist() – persists the game (to a DB?)
- TtdData data – holds all game data other than the land.
- GameTickerThread tickerThread – runs a ticker in regular interval (1 s?).
  - GameTicker ticker – modifies the world:
    - Waiting transportables in stations
    - Towns growth
    - Industry production adjustments
    - Failures, disasters…
    - Subsidies
TtdDataJsonServlet – provides data to the client.
- request: area info (x1,y1,x2,y2), changedSince [timestamp]
- JSON response: all information about the given area which changed since changedSince
  - cells
  - stations
  - …

OpenTTD Save/Load

http://svn.openttd.org/trunk/

src/saveload/map_sl.cpp

src/saveload/saveload.cpp

/**
 * Save/Load an array.
 * @param array The array being manipulated
 * @param length The length of the array in elements
 * @param conv VarType type of the atomic array (int, byte, uint64, etc.)
 */
void SlArray(void *array, size_t length, VarType conv){ ... }

src/map.cpp

uint _map_log_x;     ///< 2^_map_log_x == _map_size_x
uint _map_log_y;     ///< 2^_map_log_y == _map_size_y
uint _map_size_x;    ///< Size of the map along the X
uint _map_size_y;    ///< Size of the map along the Y
uint _map_size;      ///< The number of tiles on the map
uint _map_tile_mask; ///< _map_size - 1 (to mask the mapsize)

Tile *_m = NULL;          ///< Tiles of the map
TileExtended *_me = NULL; ///< Extended Tiles of the map

src/map_type.h

/**
 * Data that is stored per tile. Also used TileExtended for this.
 * Look at docs/landscape.html for the exact meaning of the members.
 */
struct Tile {
        byte   type_height; ///< The type (bits 4..7) and height of the northern corner
        byte   m1;          ///< Primarily used for ownership information
        uint16 m2;          ///< Primarily used for indices to towns, industries and stations
        byte   m3;          ///< General purpose
        byte   m4;          ///< General purpose
        byte   m5;          ///< General purpose
        byte   m6;          ///< Primarily used for bridges and rainforest/desert
};

http://svn.openttd.org/…ndscape.html
http://209.85.135.132/search?…
http://209.85.135.132/search?…

OpenTTD's docs: landscape OpenTTD's docs: landscape_externals OpenTTD's docs: landscape_grid

OpenTTD save file transformer

TODOs

Construction toolbars
Track and plan editation
Building functions
- First, road construction
AJAX push
Complete basic subset of tables to make the game run
Data model in Java
Vehicle path movement animation
- Will follow the „track“
- Track consists of arcs – parts of the track with the same direction.
- Each direction change is a waypoint of the animation
- Y axis movement slower than X
Get pictures from the OpenTTD project
City growth algorithm

Links

Simutrans history

Tycoonez

Geogre Zernebok (Very interesting page :)

OpenTTD forums – link to my request for OpenTTD map export

A bit of realism

But of course, for one man, this is work for years.

For now, it will just be my humble dream :)