Algorithm to make groups of units

Question

In Age of Mythology and some other strategy games, when you select multiple units and order them to move to some place, they make a "group" when they reach the desired location:

I have a Vector with several sprites, which are the selected units, the variables tarX and tarY are the target x and y. I just want an example, so you can just set the x and y position and I can adapt it to my code. Also, I would like to ask that the algorithm calls "isWalkable" for the x and y position, to determine if it's a valid position for each unit.

Answer 1

What you're looking for is basically coordinated movement. The units pathfind to their destination and when they reach it, they form a "formation".

This is a topic decently covered in the AI Game Programming Wisdom (Book 1, Book 2, Book 3 and Book 4) books. But, I'll refer you to the following articles:

Coordinated Movement - A link explaining the fundamental principles of coordinated unit movement in RTS games

and

Implementing Coordinated Movement - An article continuing from the first, that talks about how to implement this type of movement in a game.

It's written in C++ but it shouldn't be too difficult to port to any other language, as the underlying principles remain the same.

Hope that helps.

Ray