Difference between revisions of "LlApplyImpulse"
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* the initial velocity * mass = momentum when there are no other forces ( collisions, gravity ) | * the initial velocity * mass = momentum when there are no other forces ( collisions, gravity ) | ||
* the momentum is not capped to 20 | * the momentum is not capped to 20 | ||
*/ | |||
integer tid; | integer tid; | ||
vector initPos; | vector initPos; | ||
Revision as of 10:24, 20 April 2014
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Summary
Function: llApplyImpulse( vector momentum, integer local );| 72 | Function ID |
| 0.0 | Forced Delay |
| 10.0 | Energy |
Applies impulse to object
| • vector | momentum | |||
| • integer | local |
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.
- Sets an initial momentum on the object applied to the center of Mass . Momentum is the mass*velocity needed to get an initial movement of velocity if the object is not affected by other forces ( as the gravity )
- The magnitude of momentum may be scaled back by the object's available energy.
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> <lsl> /* Uselesse script , just to demo that
- the parameter is a momentum not a force
- the initial velocity * mass = momentum when there are no other forces ( collisions, gravity )
- the momentum is not capped to 20
- /
integer tid; vector initPos; vector Impulse;
default {
state_entry()
{
llSetPhysicsMaterial(GRAVITY_MULTIPLIER,0,0,0,0);
llSetStatus(STATUS_PHANTOM, TRUE);
llSetStatus(STATUS_PHYSICS, TRUE);
}
touch_end(integer n)
{
tid=llTarget(initPos=llGetPos(),30);
llSetStatus(STATUS_PHYSICS, TRUE);
Impulse = llGetMass()*<0,0,25>;
llOwnerSay(llList2Json(JSON_ARRAY, [ "Setup a Momentum=", Impulse ]));
llApplyImpulse( Impulse , FALSE);
}
moving_start()
{
llOwnerSay(llList2Json(JSON_ARRAY, [ "Velocity= ", llGetVel(), "Force=",llGetMass()*llGetAccel(), "Momentum=", Impulse ]));
}
not_at_target()
{
llSetTimerEvent(0.0);
llTargetRemove(tid);
llSetStatus(STATUS_PHYSICS, FALSE);
llSetRegionPos(initPos);
}
}
/* Example of results ["Setup a Momentum=","<0.000000, 0.000000, 183.181381>"] [10:19] Object: ["Velocity=","<0.000000, 0.000000, 25.000002>","Force=","<0.000000, 0.000000, -0.171902>","Momentum=","<0.000000, 0.000000, 183.181381>"]
- /
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
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SVC-8227 | A | llApplyImpulse now works only in the root prim. |
Signature |
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function void llApplyImpulse( vector momentum, integer local ); |
Haiku |
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In this crazy world,
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