Algodoo

lololoer - I basically understand what you want, but in order to do a correct and complete job of coding, there needs to be some details defined, such as:

1. Do you want to also detect boxes and polygons, or just circles?

2. How far is the maximum distance (in meters) that objects will be detected?

3. Will objects be moving? Will the detector be moving?

4. What kind of information do you want stored when an object is detected?

5. Do you want the detector to be triggered or free running?

1. I think an 'object' could be any physic entity. Yes, any polygon circle or box.
2. The distance doesn't matter, but anyways 100 meters.
3. Yes you've to allow the detecto and (obviously) the object.
4. Information is not required, only ypu have to make a detector with a laser that follows the object or simply update the position/entityID of the object.
5. Yes.

Thank you for your patience at this

LOL... Question number 5 is not yes/no answer! I want to know, do you want the detector to be enabled (turned ON) by a variable, OR do you want the detector to be active (detecting) all the time?

oh sorry, the detector have to be always running

That will require a LOT of coding! I could probably do it, but it will take a long time. I suggest that you try to write the script yourself, and if you run into problems and need help, just ask and maybe I and others will be able to help you.

lololoer i added a scene response to do everything you need

homieeee - Good job on the response scene, but did you see his replies to my questions? His answer number 1 says he wants to detect circles, boxes, and polygons. That makes things a lot more complicated!

Well it detects everything boxes, circles, and polygons
Laser goes 300m
can account for moving objects and moving detector
gets the entityID like he asked
and detector is always running

I don't think there's anything more he could need

Yes, you are right! When I first tried your scene with a polygon, it did not work because I later realized I had the wrong collision layer set. When I set it to B (or 2) then the detector detected it! You did a great job, and you did it so quickly! I'm impressed!