Animation Streamlined

==Animating Streamlined==
Your creations are on the move. Congratulations!
What? Now you want their wings flapping and their legs moving? 
===What are my options?===
You've got some choices to make. All the methods described here involve tradeoffs, and no one method is best in all situations. 
They work with pathfinding-enabled and non-pathfinding creations.
====Method: Animated Textures==== 
 
Animate 2D textures on a model to simulate movement. 
Most of the time a framed texture is what you'd want, but for something like a millipede's legs you might want to use a tiling texture instead. Here's a 2x2 framed texture next to a picture of it animated.
 
* This is very low server and viewer lag.
* This is 2D, so it's best for small or flat things.
The hippo flies are an example of using model design and animated textures together. The model has several sets of wings. The different frames of the texture each have one pair of wings visible, so when animated the hippo flies seem to flap their wings. Mesh models don't look glitched like a sculpt does when a texture with transparency is applied.
====Method: Flexible Prims====
 
Flexi can be used to simulate smooth movement. Sadly, I couldn't capture how smooth it looks using snapshots.
This is the only option that can be done without scripts.
Wings, tails, and hair are good candidates for this. Long flexi fur may be a lot simpler than animating legs!
* A large number of flexi prims in a scene can lag the viewer. Viewer graphic settings can impact how flexi prims are displayed.
* A flexi prim's values can be set in the edit window or changed via script.
====Method: Alpha Animation====
 
Show different pieces of your model at different times to simulate movement.
Make several models of your creature (or parts of your creature) in different poses. Join them into one linkset, usually at the torso. Alternate which parts of the linkset are visible via script.
* Higher LI/prim count than other methods. 
* It induces less server lag than moving the prims, but the viewer receives a message for every alpha change.
====Method: Prim Movement====
 
This method repositions and resizes pieces to simulate movement.
* Lower LI/prim count than alpha animation.
* This can look very smooth if the changes are fairly small.
* Moving prims that have a PRIM_PHYSICS_SHAPE_TYPE other than PRIM_PHYSICS_SHAPE_NONE can cause extreme server lag and physical collision issues (such a snagging the terrain or other objects).
* The viewer receives a message for each prim change.
* Using the edit window to resize a creature that uses prim movement can break the creature.
Click here to learn more.
====Method: Sculpt Map Swap====
 
Swap the prim's sculpt map to simulate movement.
* Lower LI/prim count than alpha animation. Beware of LI when using sculpts!
* It generates a LOT of viewer lag. The viewer receives a message for each prim change. The viewer recalculates the sculpt mesh with each change. Consider hidden prims in your creature showing the next "frame" or having a flock out.
** The impact of the recalculating can be softened by having prims within loading range showing the same sculpt shapes
** If the sculpt map texture isn't currently in the scene, it may be removed from the viewer's cache, so it may be end up being sent to the viewer multiple times. The blue-outlined cube behind the pigeon has the sculpt map textures on its sides, so the viewer doesn't remove them from the cache while the bird is in sight.
* You can set the center of a sculpted prim when designing the sculpt map. You can't do the same with mesh. Sometimes clever placement of the center can save you from having to move or rotate a prim.
Click here to learn more.
====Method: Animesh====
Animesh, or animated meshes is a technology introduced by Linden Lab in November 2018 to address most of the shortcomings of the above methods, and widen the range of possibilities, with next-to-zero impact to the region simulators, and a little impact on the viewer (but not overwhelmingly so).
Since Second Life was launched, we always had 'animated meshes'. The problem was that it was just one — namely, the standard avatar body mesh. Everything else was un-animate-able and mostly frozen in place, with the exception of flexiprims and Linden Trees. Thus the several methods described above to give a sense of movement to an object, each with its limitations.
With mesh replacing both sculpties and primitives, and becoming the de facto standard for content creation, animesh allows our meshed objects to be animated in the same way that avatars can be animated!
In particular, animesh allows:
* Using any standard mesh (within reasonable size limits and less than 100,000 triangles or so)
* A pseudo-skeleton, equivalent to the original standard avatar body, will be implied for that mesh, so the mesh can be properly rigged
* Animations are uploaded as BVH files for the original standard avatar and become assets exactly like avatar animations
* The mesh item, for all effects, is driven by an Animation Overrider
* Animations run on the viewer, not the simulator; this means that there is far less effort by the physics engine to track a moving, animated object. This is exactly how user avatar animations also work!
* Animesh can also be attached to user avatars, within limits; this allows animated pets perched on one's shoulder, for example
* There are special attachment points on user avatars using the Bento skeleton for wings, tail, etc. which can be "animeshed" in conjunction with the avatars themselves
Animesh has its own entire section here on the SL Wiki.
===How do I make it happen?===
====Physics Shape Type: None====
This value allows you to tell the physics engine to ignore prims when it is doing calculations. Your creature will explore much more efficiently if there's no need to calculate whether each toenail might be colliding with that rock! 
You can't set this to none on a root prim.
If you select an object and toggle it to none in the edit window, all the child prims will be set.
You can set this via script using llSetLinkPrimitiveParamsFast with PRIM_PHYSICS_SHAPE_TYPE set to PRIM_PHYSICS_SHAPE_NONE.
====Getting the link number====
A lot of the scripting calls used here expect you to have the link ID number. 
What's a linkset or link ID?
If you've got a choice between using the linkset calls or putting separate scripts in most of your creature's prims, go with fewer scripts. The number of scripts in an object can affect LI.
You can find the absolute link ID of a prim in your linkset, but those numbers are only reliable until the next time you decide to add or remove a prim from your build. Naming the prims in your creature useful things like "leg" or "wing" things will prevent your scripts from breaking when you decide your bunny needs a top hat.
Code snippets for finding link IDs via prim name can be found here.
====Animating a texture====
 
Use llSetTextureAnim and llSetLinkTextureAnim with a texture to simulate movement. 
SL won't allow you to upload a texture larger than 1024x1024 pixels so resolution may be an issue for textures with a lot of frames.
Animated textures on a prim can be on one face, or all faces with one direction. You also don't get to use offsets or flip. (point out Sylvan's flipped UV wheel trick here)
This animated texture script could be used on a creature to make it blink.
====Setting flexible prim values====
 
Use llSetLinkPrimitiveParamsFast and the PRIM_FLEXIBLE flag.
This flapping wings script could be used with a bird that has spread flexi wings.
====Setting alpha values====
 
Use llSetLinkAlpha to change which pieces are visible at any one time.
This alpha animation script could be used with a creature made up of differently posed mesh or sculpt models.
====Moving prims====
Use llSetLinkPrimitiveParamsFast with the prim position, rotation, and size flags.
====Swapping sculpt maps====
 
Use llSetLinkPrimitiveParamsFast with the PRIM_TYPE_SCULPT flag to set a prim's sculpt map.
This sculpt map swap script could be used with a creature to change its body pose.
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