Build an Animation Blueprint

A guided example: build a locomotion blend space, an Animation Blueprint with a state machine, bound transition rules, an upper body layer, and a montage with notifies, then validate it.

This walkthrough builds a working locomotion setup from nothing: a blend space for ground movement, an Animation Blueprint, a state machine with real transition rules, an upper body layer, and a montage with notifies. Every command in the family is listed in the Animation reference.

Build the locomotion blend space

A 2D blend space with direction across and speed up. Name and range each axis, then drop a sample per animation.

bash

cfa create_blend_space --name BS_Locomotion --path /Game/Anims --skeleton /Game/Chars/SK_Hero --kind blendspace_2d

Range the axes

Direction runs -180 to 180 and wraps, speed runs 0 to your jog speed. Do this before adding samples so the samples land where you expect.

bash

cfa set_blend_space_axis --blend-space-path /Game/Anims/BS_Locomotion --axis x --display-name Direction --min -180 --max 180

Place the samples

One call per animation. An idle row at speed 0, a walk ring, a jog ring. The blend space triangulates them for you.

bash

cfa add_blend_space_sample --blend-space-path /Game/Anims/BS_Locomotion --animation /Game/Anims/Jog_Fwd --x 0 --y 500

Create the Animation Blueprint

Bound to a skeleton, with a preview mesh so you can see it move. It arrives with an AnimGraph ready to use.

bash

cfa create_anim_blueprint --name ABP_Hero --path /Game/Anims --skeleton /Game/Chars/SK_Hero --preview-mesh /Game/Chars/SKM_Hero

Add the state machine and its states

States, plus conduits for shared entry logic and aliases that stand in for several states at once.

bash

cfa add_anim_state --blueprint-path /Game/Anims/ABP_Hero --graph AnimGraph/Locomotion --name Idle

Wire the transitions and bind their rules

Bind a bool variable as the rule. Add --rule-inverted for the way back, so leaving a state does not need a hand built NOT.

bash

cfa add_anim_transition --blueprint-path /Game/Anims/ABP_Hero --graph AnimGraph/Locomotion --from Idle --to Move --rule-variable bIsAccelerating --crossfade-duration 0.15

Add an upper body layer

Put aiming or a weapon pose on its own layer, then blend it over locomotion per bone. Share it between blueprints with a layer interface.

bash

cfa add_anim_layer --blueprint-path /Game/Anims/ABP_Hero --name UpperBodyPose

Build a montage with notifies

Assemble the montage, add named sections you can chain, then place notifies and notify states on their own tracks.

bash

cfa create_anim_montage --name AM_Attack --path /Game/Anims --skeleton /Game/Chars/SK_Hero --animation /Game/Anims/Attack_01

Tidy the graph

Lay the state machine out as a readable block, with each transition sitting between the two states it joins.

bash

cfa arrange_blueprint_graph --blueprint-path /Game/Anims/ABP_Hero --function-name AnimGraph/Locomotion

Validate before you play

Returns a verdict plus every compiler warning, including transitions that can never fire because their rule was never bound.

bash

cfa validate_anim_blueprint --blueprint-path /Game/Anims/ABP_Hero

A transition with no rule can never be taken

Adding a transition without --rule-variable leaves its Can Enter Transition pin empty, so the state machine reaches that state and never leaves it. The blueprint still compiles, so nothing stops you. Run validate_anim_blueprint and read the warnings: it names every transition that can never fire. For a time based transition set bAutomaticRuleBasedOnSequencePlayerInState instead, and clear Loop Animation on that state's sequence, because a looping animation never ends and the rule never fires.

Nested graphs are addressed by a slash path

Everything inside an Animation Blueprint is a graph, so the ordinary Blueprint graph commands work on them once you address them correctly: AnimGraph/Locomotion/Idle. Use list_anim_graphs to see the tree. Transition rule graphs are all named Transition, so a bare name is ambiguous and refused; pass the #N suffix the listing gives you.

Compile a layer interface before you implement it

A layer only reaches the implementing blueprint once it exists as a function on the interface class, which compiling is what creates. Skip that and the interface is listed but the layer graph is silently absent. It recovers: compile the interface, then the implementer. Exact parameters for any command are in the Animation reference, or run cfa describe add_anim_transition.

Loading…

PreviousRig a Character with AI NextBuild Sound with AI