Java-Gaming.org Hi !
 Featured games (91) games approved by the League of Dukes Games in Showcase (804) Games in Android Showcase (239) games submitted by our members Games in WIP (868) games currently in development
 News: Read the Java Gaming Resources, or peek at the official Java tutorials
Pages: [1]
 ignore  |  Print
 [SOLVED] Math problem with array .length  (Read 2598 times) 0 Members and 1 Guest are viewing this topic.
Yemto

Senior Devvie

Medals: 4
Exp: 3 years

 « Posted 2013-08-20 09:20:44 »

I believe this is quite simple. But I have never been good at math so I ask here before doing some thing dumb. In my game the world is build up in chunks, which is 32x32 tiles. The problem I have is moving a object to another chunk. It works as long as the coordinates are not negative. But if they are, it won't work. I have tried to do it on my own. But what that would require is an awful if statement to handles negative coordinates, and I think it could be done without an if statement

here is the code I have got working so far. I remove all attempts to do negative coordinates
 1  2  3  4  5 `int chunkX = getChunkX() + (x / Chunk.SIZE);int chunkY = getChunkY() + (y / Chunk.SIZE);        x = x%Chunk.SIZE;y = y%Chunk.SIZE;`

so what needs to happened. If a object is at 0,0 in chunk 5,5 and gets a order to move to 0,-1 the coordinates most change to 0,31 chunk 5,4

EDIT: I going to try to make it easier to understand.

I have big and small arrays set up like this.

The P is the player/Object. Now I want to move him to 3,-1 which would result in java.lang.ArrayIndexOutOfBoundsException So instead I want to move the Player/Object to 3x8 but in the big 0,-1 array. The problem is I don't know the math I need to do so I get the right big array, and the small array coordinates.

chunkX and chunkY is the big array x and y
x and y  is the small array x and y
Stranger
 « Reply #1 - Posted 2013-08-20 11:15:40 »

Anton
Yemto

Senior Devvie

Medals: 4
Exp: 3 years

 « Reply #2 - Posted 2013-08-20 13:57:59 »

Riven

« JGO Overlord »

Medals: 1371
Projects: 4
Exp: 16 years

 « Reply #3 - Posted 2013-08-20 14:01:43 »

To wrap on an axis (both positive and negative) do this:
 1 `x = (((x+n) % DIM) + DIM) % DIM`

Hi, appreciate more people! Σ ♥ = ¾
Learn how to award medals... and work your way up the social rankings!
Yemto

Senior Devvie

Medals: 4
Exp: 3 years

 « Reply #4 - Posted 2013-08-20 20:07:43 »

To wrap on an axis (both positive and negative) do this:
 1 `x = (((x+n) % DIM) + DIM) % DIM`

Thank you so much. Me and some guys at work went nuts over this problem. It's finally fixed.

Here is the code I ended up using. Just to see if someone sees any issues.
 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20 `public void setTileFromWorld(Tile t, int x, int y){    int DIM = Chunk.SIZE;    int cx = (int)Math.floor(x / (double)DIM);    x = ((x % DIM) + DIM) % DIM;    int cy = (int)Math.floor(y / (double)DIM);    y = ((y % DIM) + DIM) % DIM;    for(Chunk c : chunks){        if(cx == c.getX() && cy == c.getY()){            c.setTile(t, x, y); return;        }    }    /*    System.err.println("An error occurred while trying to place a tile");    System.err.println("Chunk X: "+cx+" X: "+x);    System.err.println("Chunk Y: "+cy+" Y: "+y);    System.err.println(t);*/}`
Pages: [1]
 ignore  |  Print

 Riven (581 views) 2019-09-04 15:33:17 hadezbladez (5510 views) 2018-11-16 13:46:03 hadezbladez (2402 views) 2018-11-16 13:41:33 hadezbladez (5772 views) 2018-11-16 13:35:35 hadezbladez (1223 views) 2018-11-16 13:32:03 EgonOlsen (4661 views) 2018-06-10 19:43:48 EgonOlsen (5682 views) 2018-06-10 19:43:44 EgonOlsen (3198 views) 2018-06-10 19:43:20 DesertCoockie (4095 views) 2018-05-13 18:23:11 nelsongames (5115 views) 2018-04-24 18:15:36
 princec 10x Ali-RS 6x philfrei 5x VaTTeRGeR 5x KaiHH 5x mudlee 5x elect 4x Rain8 3x SteveSmith 2x hansolo_ 2x gouessej 2x ral0r2 1x saocrinn 1x Akazan 1x bullen 1x Apo 1x
 A NON-ideal modular configuration for Eclipse with JavaFXby philfrei2019-12-19 19:35:12Java Gaming Resourcesby philfrei2019-05-14 16:15:13Deployment and Packagingby philfrei2019-05-08 15:15:36Deployment and Packagingby philfrei2019-05-08 15:13:34Deployment and Packagingby philfrei2019-02-17 20:25:53Deployment and Packagingby mudlee2018-08-22 18:09:50Java Gaming Resourcesby gouessej2018-08-22 08:19:41Deployment and Packagingby gouessej2018-08-22 08:04:08
 java-gaming.org is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑gaming.org