Difference between revisions of "LlApplyImpulse"

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|func_id=72|func_sleep=0.0|func_energy=10.0
|func_id=72|func_sleep=0.0|func_energy=10.0
|p1_type=vector|p1_name=force
|p1_type=vector|p1_name=force
|p2_type=integer|p2_name=local
|p2_type=integer|p2_subtype=boolean|p2_name=local
|func_footnote=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.
|func_footnote=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.
|func_desc=Applies impulse to object
|func_desc=Applies impulse to object

Revision as of 00:14, 23 December 2013

Summary

Function: llApplyImpulse( vector force, integer local );
0.0 Forced Delay
10.0 Energy

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.

Examples

<lsl> // 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);
   }

} </lsl> Make yourself a beer can, drop this script into it, and have some target practice. <lsl> 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);
   }

}

</lsl>

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

Signature

function void llApplyImpulse( vector force, integer local );