Skeletal Mesh

Skeletal Animation was introduced in UT2003 (though some partial support was implemented in the final builds of the Unreal Tournament Generation of engines).

It allows a player to be animated by specifying the movement of their bone?s, while the 'skin' twists and deforms automatically. This has the advantage of allowing some combination of animations.

Combination of animations is used only sparingly in UT2003. In the behindview you can see that your torso barely moves when you run, but in the animation browser, the animation dictates that the weapon be pointed to the side while running. The idle animation is set to override the running animation on the spine and above. Thus the bones above the spine always play the idle animation even when the lower portions are running. This is an example of animation blending in UT2003. Skeletal animation is also integrated into the Karma Ragdoll system, so is important for that reason. They are defined in actor, and are accessible from any Actor that uses DrawType = DT_Mesh.

Functions

All these functions are declared in the Actor class:

LinkSkelAnim( MeshAnimation? Anim, optional Mesh NewMesh ) (simulated, native, final)

Sets the skeletal animation settings for this actor. If you supply a mesh argument, the mesh will also be changed.

LinkMesh( Mesh NewMesh, optional bool bKeepAnim ) (simulated, native, final)

Similar to LinkSkelAnim, this only links the mesh. The optional variable specifies whether the current skeletal animation settings should be retained. If it is true, the skeletal animation settings will remain unchanged. If it is false, the skeletal animation settings will be set to none, or to the defaults included in the mesh, if applicable.

BoneRefresh() (native, final)

Forces a bone refresh to ensure that bones have been set up and updated.

AnimBlendParams(int Stage, optional float BlendAlpha, optional float InTime, optional float OutTime, optional name BoneName, optional bool bGlobalPose) [native final]

This sets the parameters for the animation blending. This is the amount that animations will be merged in the event that two conflicting animations play simulataneously on different channels. Stage is the channel that you want to set blending parameters for. InTime is the amount of time for which to interpolate in the blending. Thus, if Blendalpha is 0 and you set it to 1 with this function, using InTime of 1, it will wake 1 second before BlendAlpha is 1. At half a second it will be 0.5, etc. BlendAlpha is the amount to blend the animations. I believe that 0 is fully the channel with a lower number, 1 is fully the channel with the greater number, and 0.5 is half way (each animation applies half the motion to the bone that they would like to. Outtime is not implemented in the current build of the Unreal Engine. Bonename can be used to selectively set blending on certain bones. I do not know what bGlobalPost does.

AnimBlendToAlpha( int Stage, float TargetAlpha, float TimeInterval ) (native, final)

I believe that this is similar to AnimBlendParams, but with less parameters. It probrably executes faster too.

coords GetBoneCoords( name BoneName ) (native, final)

Returns the coordinates of a bone - This is the bone's built-in coordinate system. This could probrably be used to find the absolute rotation of a bone, using some vector maths.

rotator GetBoneRotation( name BoneName, optional int Space ) (native, final)

Returns the rotation of a bone. The optional parameter Space specifices the coordinate system (0 - local [default], 1 - global, 2 - relative to reference pose).

vector GetRootLocation() (native, final)

Returns the location of the "root" of the skeleton. Likely relative to the world.

rotator GetRootRotation() (native, final)

Returns the rotation of the "root" of the skeleton. Relative to the world origin.

vector GetRootLocationDelta() (native, final)

Retrieves the location difference since last time GetRootLocationDelta was called.

rotator GetRootRotationDelta() (native, final)

Not fully implemented yet - always returns (0,0,0).

bool AttachToBone( Actor Attachment, name BoneName ) (native, final)

Attaches an actor to the bone specified.

bool DetachFromBone( Actor Attachment ) (native, final)

Detaches the stated actor from any bone that it may be attached to.

LockRootMotion( int Lock ) (native, final)

Call with 1 (or larger) to enable, disable by calling with 0.

SetBoneScale( int Slot, optional float BoneScale, optional name BoneName ) (native, final)

Sets the "drawscale" of the bone, and of the "skin" that is considered attached to that bone. It will affect not only the bone you specified, but also all "child bones" of that bone. Slot is the "slot" that the scalar is stored in. To clear a "slot," you must call this function with just the slot and no parameters. Slots are not per-bone, they are per-actor. This is best illustrated with an example:

// This works.
SetBoneScale (0, 2, 'Spine');
SetBoneScale (1, 2, 'Head');
SetBoneScale (2, 2, 'LFARM');

// Even though these are differen't slot/bone combinations, the slots 0, 1, and 2 are
// overridden by the new bone and scalar information.
SetBoneScale (1, 2, 'Spine');
SetBoneScale (2, 2, 'Head');
SetBoneScale (0, 2, 'LFARM');

// Clear the scalars by doing this. Calling SetBoneScale(0,0), etcetera would probrably
// also work.
SetBoneScale (0);
SetBoneScale (1);
SetBoneScale (2);

// Scalars are cumulative if they are in different slots with the same bone name.
// The spine is 6 times normal size in this example.
SetBoneScale (0, 2, 'Spine');
SetBoneScale (1, 3, 'Spine');

// Fractional scalars are also possible. Here we negate slots 0 and 1 with a complementary
// scalar.
SetBoneScale(2, 0.15, 'Spine');

SetBoneDirection( name BoneName, rotator BoneTurn, optional vector BoneTrans, optional float Alpha, optional int Space ) (native, final)

Sets the rotation of a bone, relative to the world origin. (aka absolute)

SetBoneRotation( name BoneName, optional rotator BoneTurn, optional int Space, optional float Alpha ) (simulated, native, final)

Sets a bone's rotation. The Space parameter specifies the coordinate system to use (0 = local, i.e. bone [default], 1 = global, i.e. world, 2 = refbone). The Alpha parameter (default is 1.0) blends between default rotation and desired rotation. This can be used for crude interpolation, but such use could incur a slight performance penalty if this function is called frequently.

SetBoneLocation( name BoneName, optional vector BoneTrans, optional float Alpha ) (native, final)

Sets the Location of a bone. BoneName is the name of the bone to be moved. BoneTrans is the relative offset to move the bone's location to (default is <0,0,0>). The Alpha parameter (default is 1.0) blends between default location and desired location.

GetAnimParams( int Channel, out name OutSeqName, out float OutAnimFrame, out float OutAnimRate ) (native, final)

Retrieves sequence name, frame and rate of the currently active animation for this mesh.

bool AnimIsInGroup( int Channel, name GroupName ) (native, final)

Determines if the currently running animation of channel Channel (default is 0) is a member of group Group.

name GetClosestBone( vector loc, vector ray, out float boneDist, optional name BiasBone, optional float BiasDistance ) (native, final)

Finds the bone closest to the line with the origin loc and the direction ray. boneDist returns the distance to the determined bone. Zero scale bones (including bones that have a parent of zero scale) will be excluded from this calculation. BiasDistance can be used to bias the result (default is 0.0). If the distance to the best bone found is smaller than BiasDistance, then the function will return BiasBone instead.

Related Topics

•  UWSkelAnim2
• Bone Names

Discussion

Foxpaw: I think that this page is a bit more informative than the previous one - many of the functions may need experimenting with to see what the parameters do, as I generally don't mess around with optional parameters unless I know what they do.

DoctorEternal How about a tutorial somewhere that shows how to do the type of blending mentioned at the page top?

SettHere's what learned about animation blending, thanks to MrEvil.

I have a car with openning door ani. The problem was that the left and right door ani. were conflicting with each other. The solution was to use the AnimBlendParams()

AnimBlendParams(0, 1.0,,, 'RdoorBone');
AnimBlendParams(1, 1.0,,, 'LdoorBone');// give each bone it's own channel
...
PlayAnim('RdoorOpen',,, 0);
PlayAnim('LdoorOpen',,, 1);//play the ani. with channel param.

Foxpaw: I noticed something interesting today - it appears to be possible to build sounds into the animations. I'm not sure why you'd want to do it, but it appears possible. Check out ONSWeapons-A.ParasiteMine's "SpiderMineFaceTap" animation. This animation plays sound even when previewed in the editor without any UScript interaction.

Purely for curiosities sake, does anyone know how we can create this kind of sound binding to animations?

Petri: Use  AnimNotifies–more specifically, AnimNotify_Sound. You can look at the ones used in the animation in the "Notify" tab in the Animation Browser.

SuperApe: This looks like it was made well before UT2003 came out. It needs to look more like the other class pages. Marked up functions defs.

EricBlade: I was just reading a bunch of stuff on UDN last night, and it says that the *Root* functions are for a not-implemented "Root Animation" system, and the functions do nothing. Which is correct?

Raven: As far as I can tell these functions return vectors (or rotators) set to be 0.

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Category Class (UT2003)

Category Class (UT2004)

Category To Do – Make look more like other class pages. Fix hierarchy path at top, include package name.