Question

I am using a 1D vector to represent a 3D data structure, with indices 0 to x*y*z, where x, y and z are the number of cells in each direction.

In order to index a specific cell [xi][yi][zi], I use:

index = xi + x*yi + x*y*zi ;

My problem is, I can’t work out how to go the other way!

e.g. I want to get the individual coordinates represented in index 43.

I think I’ve worked out how to get xi:

xi = index % x ;

but I can’t for the life of me get the others… :/

EDIT: Hmmm. Is this right?

xi = index % x;
yi = ((index - xi)/x) % y;
zi = ((index - xi - x*yi) / x) / y ;

Answer 1

Try this:

xi =   index % x;
yi =  (index / x) % y;
zi = ((index / x) / y) % z;

This can be easily generalized as one might expect.