Setting Up a sector based grid system

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05-19-2005
Auron

Setting Up a sector based grid system

Hey everyone.

I am trying to set up a grid-based world system in a text-based game (MUD). The whole world would consist out of several locations, each location stored in it's own file.

What I want to have is that every location consist out of sector's using a 2 dimensional array, but the whole world consist of the collection of locations. Certain sector's in a location may be of different type and/or not accessable by players. I was able to create a single location so far without any problems, but as soon as I try to make a collection of locations, although it compiled fine, the game crashed when loading.

What I used was:

Code:

typedef struct sector_data SECTOR_DATA; #define MAX_X_GRID 100 #define MAX_Y_GRID 100 struct sector_data { char *description; int sector_type; } sector[MAX_X_GRID - 1][MAX_X_GRID - 1];

This worked fine when I used sector[x][y].sector_type, etc. but that would only allow me to create one location. So after that I decided to use a different way:

Code:

typedef struct sector_data SECTOR_DATA; typedef struct world_data WORLD_DATA; #define MAX_X_GRID 100 #define MAX_Y_GRID 100 #define MAX_LOCATIONS 10 struct sector_data { int sector_type; }; struct world_data { char *description; /* rather than having each sector use it */ SECTOR_DATA *sector[MAX_X_GRID - 1][MAX_Y_GRID - 1]; } world[MAX_LOCATIONS - 1];

Using this method compiled fine but everytime the game loaded the world it crashed. Is normally used world[x].description or world[i].sector[x][y].sector_type.

I am currently unsure what I have done wrong, yet even if there would be a better way. Any suggestions or help would be much appreciated.

Thank you.
05-19-2005
quzah

Well for starters, your size is wrong. Given an array of SIZE, you have accessable elements of 0 to SIZE -1. Thus:

Code:

SECTOR_DATA sector[ MAX_X_GRID ] ...

Gives you accessable elements of zero through MAX_X_GRID - 1. So when you do this:

Code:

SECTOR_DATA sector[ MAX_X_GRID -1 ] ...

You actually get accessable elements of zero through MAX_X_GRID -2. I doubt that's what you want.

The same goes for your world size array.

Anyway, there's not really enough information here to figure out what it is you're actually trying to do. You've got N world pieces, that you're trying to load. Each of these pieces go in the list of world parts. That I've got. What does one of these pieces contain? Is it just a series of sector types, like so?

Code:

wwwwww^^^^tttttt^^^^wwwww wwwww^^^^^ttttttt^^^^^www wwwww^^^^tttttt^^^^^^^www wwwww^tttttttt^^^^^^wwwww wwwww^^ttttt^^^^^^wwwwwww wwwww^^^ttttt^^^^^^wwwwww wwwwwww^^tttttt^^^^^^wwww

Or what?

Quzah.
05-19-2005
Auron

Sorry if I explained poorly.

Ok within the mud there is a "virtual world", this world exist out of locations where each location is devided into sectors, such as [0][0] or [9][9] (x and y coordinations).

Now what I am trying to accomplish is have a file called world.lst, in this file are a list of all the locations which is within the world. Now for each location within world.lst there will be a file <location>.loc (location being the name of the location) which will have all the sectors, information etc. for the location.

Now When loading up the world I would like to have each location stored on a seperate grid, so:

Code:

world.lst |- location1.loc |- grid layout |- location2.loc |- grid layout |- location3.loc |- grid layout

In actual if I want to draw the grid for location1 I would have something similar to:

Code:

int loc = 1; static char grid[MAX_BUFFER]; grid[0] = '\0'; for ( xLoop = 0; xLoop < MAX_GRID_X; xLoop++ ) for ( yLoop = 0; yLoop < MAX_GRID_Y; yLoop++ ) strcat( grid, get_sector_type( world[loc].sector[xLoop][yLoop].sector_type ) );

Where get_sector_type would be an external function called to return the appropriate ascii character for the type of sector.

So my problem is to get the structure layouts right (world[a].sector[b][c].sector_type). Hope this is a better explanation.

Code:

.......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... ..........

Looking at the above is three locations where each '.' is a sector on a x,y grid and all three locations would make up the world.
05-19-2005
quzah

Are your locations all a fixed size, or a variable size? that is to say:

Code:

.................... .................... .................... .................... .................... .................... .................... .................... .................... ....................

Where you have three areas which all fit together some how. Are gaps allowed? Is every area the same size, with the same number of sectors? There still isn't really enough information.

Well let's assume an arbitrary of world pieces, with an arbitrary number of sectors, of arbitrary sizes.

Code:

struct sector { ...sector info... }; struct location { struct sector **grid; size_t xsize, ysize; ...whatever... };

Now you do something like so:

Code:

struct location *loadlocation( FILE *fp ) { ... newloc = malloc( sizeof *newloc ); ... newloc->xsize = read xsize from file newloc->ysize = read ysize from file ... newloc->grid = malloc( sizeof( struct sector * ) * newloc->ysize ); for( y = 0; y < ysize; y++ ) newloc->grid[ y ] = malloc( sizeof( struct sector ) * newloc->xsize ); for( y = 0; y < ysize; y++ ) for( x = 0; x < xsize; x++ ) newloc->grid[ y ][ x ] = read sector info from file ... return newloc; }

Be sure you free everything correctly when you're done with it.

Or, if everything is a fixed size, get rid of the pointers and just use a 2D array in its place.

Quzah.

}
05-20-2005
Auron

Code:

%%..........@@ %%............@@ %%%.............@@ %%%....~~~~~.....@@@ This is a 20x10 sector %%%...~~~~~~~....@@@ ~ indicates water %%%....~~~~~.....@@@ % indicates trees %%%..............@@@ @ indicates rocks %%%....*=*.....@@@ *, = indicates a house ( below ) %%....***.....@@ %%..........@@

Looking at the above although it is a 20x10 grid 0,0 & 0,1 & 0,2 etc. isn't used so it is displayed as a blank spaced ' '. Where as depending on the sector type it would display the character appointed in the appropriate colour.

Code:

/---==---\ |........| This is a 10x5 sector |........| -, |, / & \ indicates walls |........| = indicates a door \--------/

Looking at the above it is a 10x5 grid where all the sectors are used.

So basically some of the locations would differ in size and certain sectors isn't used. Although those sectors isn't used it is still part of the location.

So taking the above information. I will need to load each location in a 2 dimensional array.

Code:

typedef struct sector_data { ... information ... } sector[X][Y];

Where X and Y would be define as the maximum any locations can go. (No locations would go above 100x100).

Now what I would like to do is load up a collection of locations into a new variable (let's call it world). So in the end i would use world[loc].sector[x][y].type, etc. (loc would be the current location in, x and y pointing to the current sector).

All the locations would be loaded into memory seeing that it would be pointless to load/unload the location whenever someone enters, due to the fact that it is a online multiplayer game, and also if it were to load/unload then all the objects/mobs would reset the whole time which I don't want.

Thank you.
05-20-2005
quzah

Since your sector sizes are not all the same, using an array is a waste of space. If however you want to use an array, you'll have to hard code the maximum size for X and Y, and then just load into that. However, the method I've shown will do what you want.

Quzah.
05-20-2005
Auron

Thx quzah - i will look into it.

Do you know of any tutorials or articles which could help me with this sort of thing.

Thank you.