Thread: Problems with the Diamond-Square algorithm

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 !

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