This really didn''t get a response in the Game Development section, maybe it will spark interest here... I came across a particular problem when designing the server portion of my game. On the client side, the player sees only one part of the map at one time; loading the map dynamically is not really a big thing. However, the server might need to keep track of a lot of different characters all over the place. With a map file of 4096*4096 at 6 bytes per tile, we''re looking at a 96mb file. I thought of a couple of resolutions: 1 - load the entire map into memory 2 - load portions ("regions") based on character occupancy 3 - split the map up into sections (groups of regions) and distribute server load across many machines Of course #1 requires an awful lot of resources for areas that mightn''t be accessed all at once. So we waste memory and CPU cycles maintaining the entire map. I figure #2 would be a good starting design choice, since it''s unlikely that a character will be at EVERY location that requires memory at once; this allows the server to allocate/deallocate dynamically, and avoid wasted resources. But in the event that characters DO overload the server (that means only 1024 characters online at once, ALL spread out over the map evenly to maximize server load) we''re looking at server crash, lost items and character advancement, and general playerbase upheaval. So what about a combo of #2 and #3... the final option lets many servers handle the game (in the event of a large player base), or one server handle the entire game (for a small player base). You''d have a multi-server configuration as below:

    
Server 1
{
NorthBoundary=0
WestBoundary=0
EastBoundary=4095
SouthBoundary=2047
IP=24.67.231.19
}

Server 2
{
NorthBoundary=2048
WestBoundary=0
EastBoundary=4096
SouthBoundary=4096
IP=24.67.231.36
}

  

You could add different IPs, ports even, plus maybe a custom password authentication, per server (for total servers > 1) or just host the whole thing on one machine... and with #2 map handling in effect, you don''t have to worry about overloading the server (for total servers = 1). Comments? MatrixCubed
http://MatrixCubed.org

Make that 5 bytes... I made a couple changes. They''re as follows:

  typedef struct _TILE{	unsigned char	m_cHeight;	unsigned short	m_iType;	short		m_iZLevel;} TILE, *LPTILE;  

This lets me devise up to 65,536 types of tile images, heights up to 255, and Z levels ranging in -32,768 to +32,767.

I figured this would be about the lightest a tile could get if I wanted it to be a little dynamic (not limited to 256 z-levels or tile graphics).

These tiles are needed by the client AND the server for a couple reasons: mostly, the client needs it for rendering and the server needs it for collision detection. But I want both applications to have access to all parts of a tile''s data (so I''m not going to split the files up... doesn''t help OOP very much anyways). Also, this info is static (though maybe if there are server updates like minor map fixes... the server map could be edited and auto-updated to clients when they reach edited areas). Mostly it''s not changed though.

And yup, the server application is dedicated... It''s basically a DOS-box application. It could be run from many different machines and configurations (no video hardware requirements -- yippee!), and I''m keeping it simple for when I (try to) port it to Linux.

Laters,


MatrixCubed
http://MatrixCubed.org

Don''t load world geometry data on the server.
The cleints should handle collion detection... distribute the load!

Want you really want to do, is create a list of Player & thier locations. Al la OctTree or BSP type technology, and send updates ect based on that.


Magmai Kai Holmlor
- The disgruntled & disillusioned

Hmm well if the clients handle the collision detection, then we run the risk of having clients bypass map features (i.e. something has been updated on the server, the client doesn''t know about it or hasn''t updated, and lets the player walk straight through a blocked-off area... or vice versa).

This happened a lot on the UO shard I administered... players didn''t download/install the 8mb map-update file, so wondered why they saw houses in trees, missing buildings, etc. I want to make sure this doesn''t happen... and I think it would if the only collision detection was client-side.

Same with creature and object movement... the server needs to have control of it, otherwise you get synchronization problems (a la EverQuest).

I''m trying to cover all bases, but I''m still a bit away from actually coding any of this (other than for testing purposes) ... I want to make sure everything works well in theory first.


MatrixCubed
http://MatrixCubed.org