llSetKeyframedMotion

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Revision as of 23:02, 5 July 2023 by Wulfie Reanimator (talk | contribs) (Updated examples.)
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Summary

Function: llSetKeyframedMotion( list keyframes, list options );

Specify a list of positions, orientations, and timings to be followed by an object. The object will be smoothly moved between those keyframes by the simulator.

Collisions with other nonphysical or keyframed objects will be ignored (no script events will fire and collision processing will not occur). Collisions with physical objects will be computed and reported, but the keyframed object will be unaffected by those collisions. (The physical object will be affected, however.)

• list keyframes – Strided keyframe list of the form:

Each keyframe is interpreted relative to the previous transform of the object. Time values must be 1/9s. or greater. For example, consider the following list of keyframes: 

[<0, 0, 10>, ZERO_ROTATION, 5, <0, 0, 0>, ZERO_ROTATION, 5, <0, 0, -10>, ZERO_ROTATION, 5]

This would cause the object to move up 10m over the course of 5s. It would then remain at the location for 5s before moving down 10m over the course of another 5s.

An empty list will terminate any keyframed animation currently playing.

• list options – modifiers and future options

Specification

The following flags will be supported within the options list:

  • KFM_MODE followed by one of: KFM_LOOP, KFM_REVERSE, KFM_FORWARD, or KFM_PING_PONG will specify the playback mode. Defaults to KFM_FORWARD. Must be specified when the keyframe list is provided.
  • KFM_DATA followed by a bitwise combination of: KFM_TRANSLATION and KFM_ROTATION. By default both rotations and translations must be provided. If you specify one or the other, you should only include translations or rotations in your keyframe list. Must be specified at the time the keyframe list is provided.
  • KFM_COMMAND followed by one of: KFM_CMD_STOP, KFM_CMD_PLAY, KFM_CMD_PAUSE. STOP will pause the animation AND reset it to the beginning. PAUSE will pause the animation without resetting. PLAY will resume a paused or stopped animation.

Note that if KFM_COMMAND is provided in the options list, it must be the only option in the list, and cannot be specified in the same function call that sets the keyframes list.

Inter-region movement is supported; simply specify a target keyframe that would place the object outside the sim boundaries and it will cross over. This seems to provide the same effect as pausing the animation when it is in limbo between the two regions, but the viewer continues to interpolate its movement. It will jump back to the sim border and continue on the same speed, although the time between waypoints will be increased due to the sim crossing. Make sure you factor this into your system.

Since keyframed motion is a prim property rather than restricted to the script that called it, you can use multiple scripts to control, pause, or restart the same keyframed motion without passing the original keyframe list provided. Just pass an empty list for keyframes list, and the KFM_COMMAND followed by the command in the options list.

options flags Additional Parameters Description
[ KFM_COMMAND ] 0 [ integer command ] Sets the command
KFM_CMD_PLAY 0 ?
KFM_CMD_STOP 1 ?
KFM_CMD_PAUSE 2 ?
[ KFM_MODE ] 1 [ integer mode ] Sets the playback modeDefaults to KFM_FORWARD
KFM_FORWARD 0 ?
KFM_LOOP 1 ?
KFM_PING_PONG 2 ?
KFM_REVERSE 3 ?
[ KFM_DATA ] 2 [ integer fields ] Sets what data the keyframes containDefaults to (KFM_ROTATION | KFM_TRANSLATION)
KFM_ROTATION 0x1 ?
KFM_TRANSLATION 0x2 ?

Caveats

  • This function does not work in attachments.
  • This function can only be called on NON-physical objects. In the future it could be extended to support physical objects, but this is more complicated as collisions could prevent the object from reaching its goal positions on time.
  • You cannot use scripts to move any prim in the linkset while the keyframed motion is active. If you must, first pause and restart it with KFM_CMD_PLAY when done. #Example
  • Collisions with avatars affect the angular movement of the object and it may not reach the final rotation.
  • This function can only be called on the root prim of a linkset.
  • This function requires the linkset to use the Prim Equivalency system. However, it keyframed objects will not receive the dynamics penalty and can have a physics weight of up to 64.
  • Linear velocity greater than Second Life's maximum of 250 meters per second will produce an error on DEBUG_CHANNEL.
  • llSetKeyframedMotion is implemented in terms of frames and not real time. To avoid a drift from the expected positions and rotations, use times which are integer multiples of 1/45, e.g. 20.0/45.0, 40.0/45.0, 90.0/45.0, etc. Forum Thread KFM claims delta times must be larger than 0.1 seconds; in practice, however, delta times slightly over 0.1 will produce an error on DEBUG_CHANNEL. Testing shows a minimum delta time is about 6/45 (.13333) seconds.
  • There are a few bugs in the avatar animation system that may cause strange looking animations to play when standing on a moving platform (e.g., walking in place, feet-at-pelvis). We hope to fix these in the future, but doing so is out of scope for this feature.
  • As with dynamic objects, objects moving using this function are paused when they are selected by an avatar with adequate permissions (object owner, passenger, etc). When such an avatar deselects the object, motion resumes, even if the object had been paused using KFM_CMD_PAUSE.
  • A Key Framed Motion is a prim property in some respect. When a KFM_LOOP or KFM_PING_PONG is initiated the the motion is preserved after the script is removed. I.E. The prim will continue what motion it had. It will survive take and copy. It will survive server restart.
  • Inter region movement is far from perfect. Crossing from sim 1 to sim 2 using a Key Frame list with numerous frames on a curved path will pick up conspicuous errors on the crossing and when reversed by [ KFM_MODE, KFM_REVERSE ] the object will stay in sim 2 and never return to sim 1

Examples

A KFM object must use the new Prim Equivalency system in order to work. One of many ways to achieve this is to make sure the object uses Convex Hull for its physics shape. (Mainly new prims need a workaround like this. Mesh objects always use the new Prim Equivalency system.) 

llSetLinkPrimitiveParamsFast(LINK_THIS, [PRIM_PHYSICS_SHAPE_TYPE, PRIM_PHYSICS_SHAPE_CONVEX]);

This is a simple example of back-and-forth or "ping pong" motion, using only positions and time. 

llSetKeyframedMotion([<0.0, 0.0, 10.0>, 5, <0.0, 0.0, -10.0>, 5], [KFM_DATA, KFM_TRANSLATION, KFM_MODE, KFM_PING_PONG]);

This example includes position, rotation, and time. 

llSetKeyframedMotion(
    [<0.0, 0.0, 10.0>, llEuler2Rot(<90, 45, 180> * DEG_TO_RAD), 5,
     <0.0, 0.0, -10.0>, llEuler2Rot(<270, 225, 360> * DEG_TO_RAD), 5],
    [KFM_MODE, KFM_REVERSE]);

Pause-Play

If you need to update a KFM object's position, you will need to pause KFM and continue it afterwards. 

llSetKeyframedMotion([],[KFM_COMMAND, KFM_CMD_PAUSE]);
// Modify prim positions here
llSetKeyframedMotion([],[KFM_COMMAND, KFM_CMD_PLAY]);

Sample Script - Key Framed Follower

Under some circumstances, rotations will generate a run-time error unless they are normalized. This script illustrates a way to use llKeyframedMotion to create a follower -- think, for example, of a cart behind a vehicle -- using normalized target rotation. 

key scriptedObjectToFollow = "daf4847b-967d-bff6-69c0-fd7022241be7";
integer isSensorRepeatOn;

rotation NormalizeRotation(rotation Q)
{
    float MagQ = llSqrt(Q.x*Q.x + Q.y*Q.y +Q.z*Q.z + Q.s*Q.s);
    return <Q.x/MagQ, Q.y/MagQ, Q.z/MagQ, Q.s/MagQ>;
}

default
{
    state_entry()
    {
        llSetLinkPrimitiveParamsFast(LINK_ROOT, [
            PRIM_PHYSICS_SHAPE_TYPE, PRIM_PHYSICS_SHAPE_CONVEX,
            PRIM_LINK_TARGET, LINK_ALL_CHILDREN,
            PRIM_PHYSICS_SHAPE_TYPE, PRIM_PHYSICS_SHAPE_NONE
        ]);
    }

    touch_start(integer total_number)
    {
        isSensorRepeatOn = !isSensorRepeatOn;

        if (isSensorRepeatOn)
        {
            llSay(PUBLIC_CHANNEL, "Sensor repeat switched on!");
            llSensorRepeat("", scriptedObjectToFollow, SCRIPTED, 10.0, PI, 0.3);
        }
        else
        {
            llSensorRemove();
        }
    }

    sensor(integer num_detected)
    {
        vector ownPosition = llGetPos();
        rotation ownRotation = llGetRot();
        vector detectedPosition = llDetectedPos(0);
        rotation detectedRotation = llDetectedRot(0);

        vector kfmPosition = (detectedPosition - ownPosition) + <-1.0, 0.0, 0.2> * detectedRotation;
        rotation kfmRotation = NormalizeRotation(detectedRotation / ownRotation);
        llSetKeyframedMotion([kfmPosition, kfmRotation, 0.15], []);
    }
}

Universal Hinged Motion in 8 Key Frames

The script will turn a box prim around one edge parallel to the prim's Y-axis
The script will work for any prim orientation
Note that the smallest accepted time per frame is 1/9S=0.11111111S and NOT 0.1S

float angleEnd=PI_BY_TWO;
float speed=0.2; // m/S
float steps=8.0; // number of Key Frames
float step=0.0;
list KFMlist=[];
vector V;
integer open=TRUE;
vector basePos;
rotation baseRot;

float motion_time( float mt)
{
    mt = llRound(45.0*mt)/45.0;
    if ( mt > 0.11111111 ) return mt;
    else return 0.11111111;
}

default
{
    state_entry()
    {
        llSetMemoryLimit(0x2000);
        llSetPrimitiveParams([PRIM_PHYSICS_SHAPE_TYPE, PRIM_PHYSICS_SHAPE_CONVEX]);
        basePos = llGetPos();
        baseRot = llGetRot();
        vector v1 = 0.5*llGetScale()*llGetRot();
        rotation deltaRot = llEuler2Rot(< 0.0, angleEnd/steps, 0.0>);
        while ( step < steps )
        {
            V = v1*llAxisAngle2Rot(llRot2Left(llGetRot()), angleEnd*step/steps);
            V = v1*llAxisAngle2Rot(llRot2Left(llGetRot()), angleEnd*(step+1.0)/steps) - V;
            KFMlist += [V, deltaRot, motion_time(llVecMag(V)/speed)];
            step += 1.0;
        }
    }
    touch_end( integer n)
    {
        llSetKeyframedMotion( [], []);
        if ( open )
        {
            llSetPrimitiveParams([PRIM_POSITION, basePos, PRIM_ROTATION, baseRot]);
            llSetKeyframedMotion( KFMlist, []);
        }
        else
        {
            llSetKeyframedMotion( KFMlist, [KFM_MODE, KFM_REVERSE]);
        }
        open = !open;
    }
    on_rez( integer n) { llResetScript(); }
}

After editing prim position, rotation and/or size the script should be reset in order to update the motion

Continuous Spin

The following example does the same thing as using llTargetOmega(<0.0,0.0,1.0>,PI,1.0) to make a prim rotate continuously around its Z-axis, assuming that the prim is set to convex hull and is non-physical. 

integer gON;

default
{
    touch_start(integer total_number)
    {
        gON = !gON;
        if (gON)
        {
            // Make repeated rotations of PI/2 radians, each taking 0.5 seconds
            llSetKeyframedMotion([llEuler2Rot(<0.0,0.0,PI/2>), 0.5],[KFM_DATA,KFM_ROTATION, KFM_MODE,KFM_LOOP]);
        }
        else
        {
            llSetKeyframedMotion([],[]);
        }
    }
}

More Examples

Notes

Potential Use Cases:

  • Elevators
  • Moving platforms
  • Trains/Fixed-Track Vehicles
  • Moving doors/walls/gates
  • Windmills and other machines

Targeted coordinate systems: The Translation is in Global coordinates, the Rotation in Local coordinates

  • Say: a move on the X-axis will move the object along the global, region X-axis no matter how the object is rotated
  • Say: a rotate around the X-axis will rotate the object around it's local, prim X-axis no matter the object's rotation
  • When the object is not rotated in the global system you won't notice the difference

Deep Notes

History

Date of Release 09/11/2011

Signature

function void llSetKeyframedMotion( list keyframes, list options );

Haiku

This is how they move,
Non-phys life for my critters
Smooth, no collisions.
— Progenitor Resident

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