[UE4]Animation Blending Notes

keywords：UE4、Animation Blending Nodes、Examples

Offical Docs

Blend Nodes

Specifications of Animation Blend Nodes：Blend Nodes
https://docs.unrealengine.com/en-us/Engine/Animation/NodeReference/Blend

Examples

Layered blend per bone (upper body blending)

Reference of Animation Blending Example：

EpicSurvivalGameSeries\SurvivalGame\Content\AnimStarterPack\Player_AnimBP

Logic achieved in this Blueprint: Rotate Aiming direction to the camera view direction
Site: https://github.com/tomlooman/EpicSurvivalGameSeries

APIs in Common

Blend Option

AlphaBlend.h

UENUM()
enum class EAlphaBlendOption : uint8
{
    // Linear interpolation
    Linear = 0,
    // Cubic-in interpolation
    Cubic,
    // Hermite-Cubic
    HermiteCubic,
    // Sinusoidal interpolation
    Sinusoidal,
    // Quadratic in-out interpolation
    QuadraticInOut,
    // Cubic in-out interpolation
    CubicInOut,
    // Quartic in-out interpolation
    QuarticInOut,
    // Quintic in-out interpolation
    QuinticInOut,
    // Circular-in interpolation
    CircularIn,
    // Circular-out interpolation
    CircularOut,
    // Circular in-out interpolation
    CircularInOut,
    // Exponential-in interpolation
    ExpIn,
    // Exponential-Out interpolation
    ExpOut,
    // Exponential in-out interpolation
    ExpInOut,
    // Custom interpolation, will use custom curve inside an FAlphaBlend or linear if none has been set
    Custom,
};

Explanation:

• ExpOut: Speed down first then speed up when playing animation.
• ExpIn: Speed up first then speed down when playing animation.

Animation Blend Modes
https://docs.unrealengine.com/en-us/Engine/Animation/NonLinearBlends

Usages

How to switch Animation Rotate Space when Montage Blending

Issue:
If want to blend shooting animation when character is moving, by default the shoot animation would rotate using the Space of moving animation(blend using DefaultSlot), but it may cause the shooting animation(blend using UpperBody) rotate to the wrong direction when blend per bone.

Solution:
Check Mesh Space Rotation Blend in Layered blend per bone

How to keep in sync when using Layered blend per bone

Issue:
When using Layered blend per bone, lower body animation would be reset when play upper body animation.

Solution:
Set the same Sync Group in BlendSpace of movement.

How to keep in sync when using Layered blend per bone
https://forums.unrealengine.com/development-discussion/animation/1403030-how-to-keep-in-sync-when-using-layered-blend-per-bone

How to use Blend Depth?

Reference
What does the ‘Blend Depth’ parameter in ‘Layered Blend Per Bone’ do?
https://answers.unrealengine.com/questions/387906/what-does-the-blend-depth-parameter-in-layered-ble.html
[Documentation]How to use Blend Depth in Layered blend per bone node?
https://answers.unrealengine.com/questions/336798/how-to-use-blend-depth-in-layered-blend-per-bone-n.html

How to execute Transform (Modify) Bone and Layered Blend and PlayAnimMontage at the same time

Just execute Transform (Modify) Bone and Layered Blend before Final Animation Pose node, then bone’s transform would stack to pose of PlayAnimMontage.

Issues

Blending didn’t work properly in Animation Blueprint

Issue:
Blending didn’t work properly in Animation Blueprint.

May be caused by:
It’s issue of engine: Animation Blueprint was create in engine at low version, and then you update engine to the higher version.

Solution:
Create Animation Blueprint in higher version of UE4Editor.

Switch Animation Blueprint at run-time

if(NewAnimClass)
{
    SKMesh->SetAnimInstanceClass(nullptr);
    SKMesh->SetAnimInstanceClass(NewAnimClass);    
}

有作用者器宇定是不凡，有智慧者才情决然不露。----弘一法师