LlApplyImpulse

From Second Life Wiki

Jump to: navigation, search

Contents

Summary

Function: llApplyImpulse( vector force, integer local );

Applies impulse to object

• vector force
• integer local boolean, if TRUE force is treated as a local directional vector, if FALSE force is treated as a region directional vector

Instantaneous impulse. llSetForce has continuous push. "Instantaneous" seems to mean a one second impulse, as an application of a force (in newtons) equal to the object's mass (in kg) for one second will accelerate it to a velocity of 1 (in meters per second), which appears to be what happens with this function.

Caveats

  • Only works in physics-enabled objects.
  • The magnitude of force may be scaled back by the object's available energy.
  • The maximum magnitude of force is 20.0 and if it exceeds that it will be scaled back.
  • Silently fails when not called from inside the root prim.
All Issues ~ Search JIRA for related Bugs

Examples

//  Rez an object, and drop this script in it.
//  This will launch it at the owner.
 
default
{
    state_entry()
    {
        key ownerKey = llGetOwner();
        vector ownerPosition = llList2Vector(llGetObjectDetails(ownerKey, [OBJECT_POS]), 0);
 
//  if the owner is not in the sim, stop fooling around
        if (llGetAgentSize(ownerKey) == ZERO_VECTOR)
            return;
 
//  else
        llSetStatus(STATUS_PHYSICS, TRUE);
 
        vector objectPosition = llGetPos();
        vector direction = llVecNorm(ownerPosition - objectPosition);
 
        llApplyImpulse(direction * 100, 0);
    }
}

Make yourself a beer can, drop this script into it, and have some target practice.

vector gHome;
integer gHit;
 
default
{
    collision_start(integer num)
    {
        if (!gHit)
        {
            llSetTimerEvent(15.0);
            gHome = llGetPos();
            gHit = TRUE;
        }
        llSetStatus(STATUS_PHYSICS, TRUE);
        llTriggerSound("b90ed62a-2737-b911-bb53-6b9228bbc933",1.0);
        llApplyImpulse(llGetMass()*<0,0,5.0>,TRUE);
        llApplyRotationalImpulse(llGetMass()*<llFrand(1.0),llFrand(1.0),llFrand(1.0)>,TRUE);
        llResetTime();
    }
 
    land_collision(vector where)
    {
        if (llGetTime() < 0.5)
        {
            llResetTime();
            llApplyImpulse(llGetMass()*<0,0,llFrand(1.0)>,TRUE);
            llApplyRotationalImpulse(llGetMass()*<llFrand(1.0),llFrand(1.0),llFrand(1.0)>,TRUE);
        }
    }
 
    timer()
    {
        llSetStatus(STATUS_PHYSICS,FALSE);
        gHit = FALSE;
        llSetRegionPos(gHome);  // Send the can home, even if more than 10m away
        llSetRot(ZERO_ROTATION);
        llSetTimerEvent(0.0);
    }
}

See Also

Functions

•  llApplyRotationalImpulse
•  llSetForce Set continuous force

Deep Notes

Unpredictability

Taken from Simulator User Group/Transcripts/2012.10.05

[16:24] Andrew Linden: the llApplyImpulse() is even more unpredictable
[16:24] Andrew Linden: because it uses the legacy script "energy budget"
[16:25] Andrew Linden: which will attenuate the results if the scripted object doesn't have enough "energy" to execute the impulse that it wants
[16:25] Andrew Linden: also, that llApplyImpulse() has great griefing potential
[16:25] Andrew Linden: so we hobbled it a long time ago with a very high energy consumption rate

All Issues

~ Search JIRA for related Issues
   llApplyImpulse now works only in the root prim.
This article wasn't helpful for you? Maybe the related article at the LSL Wiki is able to bring enlightenment.
Personal tools