LSL Wiki Mirror 10-5-2006: touch

touch_start(integer num_detected)

This event is raised when an agent first touches the object the script is attached to. The number of touching agents is passed to the script in the num_detected parameter. Information on those objects may be gathered via the llDetected* functions.

Event:	Triggered:	Triggered multiple times:
`touch()`	while a user is clicking on the object.	YES
`touch_start()`	when a user starts clicking on the object.	NO
`touch_end()`	when a user stops clicking on the object.	NO

Notes:

"Touch" means "click on", not "collide with"; to deal with collisions, use the collision, collision_start, and collision_end events.
A script containing a touch, touch_start, or touch_end event may be subject to "prim drift" caused by the user dragging the object when they mean to click it. To avoid this, use llSetStatus(STATUS_BLOCK_GRAB, TRUE) to block "grabs".

See also the llSetTouchText and llPassTouches functions.

Q: I see a lot of llDetected*(0), which seems like hacky laziness since even though this is a singular event and so unlikely to coincide, it seems possible for two touch starts to be described in a single event. Does it work that way?
A: Yes, multiple touches can be combined into a single event, but since this is rare you can get away with just checking index 0. When you suspect things get clicked a lot and close together, such as perhaps in competitive games, you should use a for or while loop to step though all the avatar references.

You can also time how long the touch went for with this quick hack:

//By Charlie Rezillo
float time = 0.1;
default
{
    touch_start(integer num_detected)
    {
        llSetTimerEvent(0.1);
    }
    timer()
    {
        time = time + 0.1;
    }
    touch_end(integer num_detected)
    {
        llSetTimerEvent(0.0);
        llInstantMessage(llDetectedKey(0),llDetectedName(0) + " you held down your mouse button for " + (string)time + " seconds.");
        time  = 0.0;
    }
}

Events

LSL Wiki Mirror 10-5-2006: touch_start