Problems with the Diamond-Square algorithm

[Whiteclaws]

Hi everyone ,

My name is Whiteclaws , and I'm new here , this my fifth try at the Diamond-Square algorithm , and I feel like it's time to ask for some help , p.s; I started learning Java yesterday , so take it easy on me ( the last 4 tries were on a drag n' drop engine )

I know what is the problem , but I don't know how to fix it !

Basically , this ;

package Array.Generation.DiamondSquare;
 
public class DiamondSquare {
 
    public static void main(String []args){
 
 
        // Size 2n+1
        int n = 8 ;
 
        //DO NOT CHANGE
        int Size = 2^n+1 ;
 
        //Creating Basic Array (l*l) {L}
        double[][] Array = new double[Size][Size];
 
        //Initialise array
 
        /* SEED
 
        tl     tr
          *   *
            *
          *   *
        bl     br
 
        */
 
        double tl = 0.5 ;
        double bl = 0.2 ;
        double tr = 0.8 ;
        double br = 0.4 ;
 
                // Putting Values (X , Y)
                Array[0][0] = tl ;
                Array[0][Size-1]= bl ;
                Array[Size-1][0]= tr ;
                Array[Size-1][Size-1]= br ;
 
 
        int Space = Size ;
 
        //Start of the loop
        while(Space > 1) {
            Space = Space/2 ;
 
            for(int y = 0 ; y != (Size/Space)-1 ; y++) {
                for(int x = 0 ; x != (Size/Space)-1 ; x++) {
 
                               //Square
 
    Array[x+Space][y+Space] =  Array[x][y]+                         // Top Left
                               Array[x+Space*2][y]+               // Top Right
                               Array[x][y+Space*2]+               // Bottom Left
                               Array[x+Space*2][y+Space*2]/4 ;  // Bottom Right
 
                               //Diamond
 
 
 
                                /* Left
                                +   o |
                                - +   | Sum all the + and divide by 3 to get - !
                                +   o |
                                */
 
              Array[x][y+Space]= Array[x][y]+
                                 Array[x+Space][y+Space]+
                                 Array[x][y+Space*2]/3;
 
                                /* Right
                                o   +  |
                                  + -  | Sum all the + and divide by 3 to get - !
                                o   +  |
                                */
 
      Array[x+Space*2][y+Space]= Array[x+Space*2][y]+
                                 Array[x+Space][y+Space]+
                                 Array[x+Space*2][y+Space*2]/3;
 
 
                                /* Up
                                + - +  |
                                  +    | Sum all the + and divide by 3 to get - !
                                o   o  |
                                */
 
              Array[x+Space][y]= Array[x+Space*2][y]+
                                 Array[x+Space][y+Space]+
                                 Array[x][y]/3;
 
 
                                /* Down
                                o   o  |
                                  +    | Sum all the + and divide by 3 to get - !
                                + - +  |
                                */
 
      Array[x+Space][y+Space*2]= Array[x+Space*2][y+Space*2]+
                                 Array[x+Space][y+Space]+
                                 Array[x][y+Space*2]/3;
 
                }
            }
 
        }
 
    }
 
  }

Is my last try , and it's working for 2 , but otherwise , it's throwing an error of outbound

Any ideas on how to fix this

Cheers !

[GregBrannon]

You say you know what the problem is, so please describe what you think the problem is and any guesses you have about how to fix it.

Please post your errors and copies of runs that result in errors. Just copy from your terminal and paste between code or quote tags as you did above.

Edit:

These statements are suspect:

            for(int y = 0 ; y != (Size/Space)-1 ; y++) {
                for(int x = 0 ; x != (Size/Space)-1 ; x++) {

It's more typical (and safer) to provide an upper limit for the loop control variable when it is increasing in value using either '<' or '<='.

Edit 2:

Also, what is the "Diamond-Square" algorithm. It may be a common term in your world, but it's not in mine.

[jps]

Welcome to the forum
Please see the Announcements page for the use of code tags

[Whiteclaws]

Thank you jps !

the array is going out of bounds and causing an error to pop up , because the center is sometimes badly placed

I don't know much on how to fix that ;

About the diamond-square algorithm

There's multiple articles

Basically






Cheers !

Edit :

My bad , totally forgot about the reason of the problem

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 11
at Array.Generation.DiamondSquare.DiamondSquare.main( DiamondSquare.java:52)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main (AppMain.java:120)


Edit2 :

Oh , I made a small error , I suspected that , it shouldn't be -1 but -2

I'll keep you tuned in with my progress on this one

[jps]

The Arrays tutorial should help discover the cause