Few Questions: Teleport if person has particular object, Disable Invisibility

Hi, I have two questions.

Is there a way to detect if a person touching an object is wearing a particular object? By this I mean, I want to only teleport people in to my arena if they are, say, wearing one of my backpacks.

Is there a way to do the above but using a proximity sensor? By this I mean, can I kick someone out of my arena (I know how to do the kicking) if someone is sensed as not wearing my backpack?

Is there a way to detect wether a player is invisible... to prevent people cheating in targeting games? By this I mean, could I add code to an object, like the above mentioned backback, that would force the wearer to remain visible at all times (while wearing the object).

Any help on any of these topics would be greatly appreciated.

You could handle this through using a chat channel.

The backpack listens for a particular message from a "sensor" in the arena or on the teleporter.

On the teleporter, when someone sits or touches the teleporter, it uses llSay to send out a command. The backpack listens for that message and responds with a particular reply that the teleporter listens for.

Same goes for the sensor. It periodically sends out a chat command and listens for a response from the backpack. Maybe this command is only sent out from the sensor when it senses the a new avatar within a certain range.

Depending on the size of the arena, you might want to use llShout instead of llSay.

As for detecting if an av is invisible, I'm afraid there's really no effective way to do that. You can't detect if an av is wearing an attachment (such as an invisiprim) if that attachment wasn't specifically scripted for detection. And people can still turn "invisible" without using an attachment by activating an animation that, say, sends their avatar underground.

Unfortunately, SL simply doesn't give you the degree of control you need in order to make these kinds of games cheat-proof.

Thanks for the feedback guys. The communication idea is great, I will use it.

Its a shame about the invis... does anyone know the limits on the "No External Scripts" ... in a nother post it was mentioned it limits out at 15m, which is not good because my arena is taller than that... also, even if the height isn't and issue, does it work on invis scripts?

I use invisible prims in many of my mech and animal avatars and they *do* work in no script zones. this is because of the very nature of the invisibility. all the script does is load a certain texture that likes to hide everything behind it including avatars, shiney effects, things with an alpha value, and particle effects. maybe if there was a way to detect that a certain texture was being used this would work, but that's "unpossible" as far as I know.