I'm currently attempting to create a small game using PD and Gem. The idea is that the player gets a blank Gem window and has to locate an invisible object somewhere in the window by clicking around.

Each click plays a sound file that varies in volume depending on how close the player is to the object (louder is closer). The player only gets a certain number of clicks to find the object.

The part I'm struggling with at the moment is how to detect whether or not the object is being clicked. I've created the gemmouse object so PD is aware where the mouse is and when it is being clicked, but I don't know how to make something trigger when the mouse clicks on the object specifically.

here's a quick example of how to find a square.

for other shapes, there might be a bit more maths involved

http://www.pdpatchrepo.info/hurleur/findSquare.pd

another option would be to use the pmpd library, there are objects designed for test collision that would do exactly what you want.

by sending your mouse position to [tSquare2D] or [tCircle2D] (see help file) you will not only get the results of the test collision but also the distance from the center of the shape (useful to generate a different sound according to the click position).