sonar like 2d array

[nimbus2506]

hi I'm trying to do trying to find the distance of a given point within a 2d array.

e.g

4 3 2 2 2 2
4 3 2 1 1 1
4 3 2 1 P 1
4 3 2 1 1 1
4 3 2 2 2 2

where P is a point. In order to do this. I'm planning on splitting the area up in 4 triangles, hence the sonar.

\ 0 0 0 /
0 \ 0 / 0
0 0 p 0 0
0 / 0 \ 0
/ 0 0 0 \

Of course to do this example would be easy because it's just j>i && j<max-1

However if I were to move the P to the left it would be different.

I have one couple of for loops to find the P and place the coordinates under m and n integers.

for(i=0;i<MAX;i++){
        for(j=0;j<MAX;j++){
            if(j<n && i<m ){
                arr[i][j]=m-j;
            }
        }
}

This comes out as

5 4 3 2 1 0
5 4 3 2 1 0
5 4 3 2 1 0
5 4 3 2 1 0
5 4 3 2 1 0
0 0 0 0 0 P

So it's half right. The numbers that are wrong are depended on the i location. So it's basically what I did with the numbers on the left...
arr[i][j]=n-i;

Any suggestions on how I can get the point to be split up in triangles??


update: j-i<=m-n && i+j<=n+m works for the left hand side. Would this be how you all would do it?

update Doesn't work when n and m are 1,1

[tabstop]

Given that the thing you are to trying to calculate is a trivial computation (i.e. subtract coordinates and take an absolute value), is there a reason to split the thing up into triangles in the first place?

[nimbus2506]

Probably me trying to make this more complicated than it actually is.

I'm split it up because the top triangle will need to be subtracted by i compared to the bottom triangle that will need to be increased by i-MAX

The left triangle will be depended on where Pj is located. So that it will be subtracted by j compared to the right triangle.

Thought by splitting it up into triangles. I can use these if statements to use the correct formula.

[iMalc]

It looks to me like you want the number of each cell to be equal to:

abs(P.x - col) + abs(P.y - row)

This would give the following for P = (4, 2):

 4 3 2 2 2 2
 4 3 2 1 1 1
 4 3 2 1 0 1
 4 3 2 1 1 1
 4 3 2 2 2 2