Why does Blend Poses by Bool snap instead of blend?

True Blend Time and False Blend Time on the node default to 0. Set both to 0.2-0.4 seconds. Without these, the node hard-cuts between the two input poses.

Should I use Blend by Bool or Blend by Enum?

Bool for two states. Enum for 3+. Each branch has its own per-state blend time. Bool is simpler when you only have on/off.

Why does the bool keep flickering?

Source data jitters around the true/false threshold. Apply hysteresis: turn true above 0.55, false below 0.45. Or smooth the input variable in BlueprintUpdateAnimation.

Fix: Unreal Blend by Bool Snaps Without Blend

Quick answer: Set Blend Poses by Bool node’s True Blend Time and False Blend Time to 0.2–0.4. Apply hysteresis to the input bool to prevent rapid toggles.

AnimBP uses Blend Poses by Bool to switch between idle and crouch poses. Toggle is instant, jarring. Blend Times are zero.

The Symptom

Bool flip causes immediate pose change. No interpolation. Looks broken or robotic.

The Fix

Right-click the node in AnimGraph → Details:

Blend Poses by Bool:
  True Blend Time:  0.25
  False Blend Time: 0.25
  Reset Child On Activation: true

Hysteresis

If the bool flickers around a numerical threshold:

bool NewCrouching = UKismetMathLibrary::SelectBool(
    bWasCrouching,
    Speed < 100.0f,        // hi-to-lo
    Speed < 120.0f);       // lo-to-hi (wider)
bWasCrouching = NewCrouching;

Wider window for staying than for entering. Stops chatter.

Verifying

Toggle bool. Pose blends over the configured time. Without Blend Times: instant. Hysteresis prevents rapid toggles producing visible noise.

“Set blend times. Hysteresis on input. Smooth toggles.”

Related Issues

For AnimBP state machine, see state machine. For state machine blend out cut, see blend out.

Times set. Hysteresis. Pose eases.