通过 X 和 Y 获取索引

Question

There's a way to get X and Y based on Index like

x = index % columns;
y = index / columns;

How can I reverse this and get Index based on X and Y?

Answer 1

Assuming we're dealing with integers here, if you have the following code:

x = index % columns; // get the remainder of dividing index by columns 
y = index / columns; // get the result of dividing index by columnsn

Then the reverse would be:

index = y * columns + x;