Animation demo

The engine's animation tools side by side on one floor:

• A mannequin you steer while it keeps facing the way the camera looks. One 2D blend space (kke::BlendSpace2D) over idle, a walk in eight directions and a forward jog picks the clips from its velocity in its own frame; the panel shows each clip's weight live.
• Two copies of it modelled in an A-pose (arms 45 degrees down) that copy its pose every frame (kke::PoseRetarget). The left one has rest matching off: its arms stay 45 degrees low in every pose. The right one has it on: it moves exactly like the mannequin.
• Two tentacles that reach for the mannequin's head when it comes near, and sway about when it doesn't: FABRIK (green, no limits) and CCD with a bend limit per joint and damping (purple). Joints bent past the limit turn red.

Start here for characters that strafe and back off while aiming, characters from other packs playing your clips, or tails, tentacles and other long chains that must bend like a body does. The engine side is in docs/MOVEMENT.md (blend spaces, retargeting) and docs/PROCEDURAL_ANIMATION.md (FABRIK and CCD).

Run it

The executable is anim_demo (kke_add_game(anim_demo ...) in CMakeLists.txt). The mannequin and its clips come from the Universal Animation Library (Quaternius, CC0): assets/animations/UAL1_Standard.fbx, and UAL2.fbx beside it (or the "Universal Animation Library 2" pack) for the eight-way walk. Without UAL2 the mannequin turns to walk forward; without UAL1 only the tentacles play (the panel says so).

cmake --build build --target anim_demo
cd build/bin
./anim_demo
KKE_ANIM_REST=1 ./anim_demo                       # everyone in the clips' rest pose
KKE_ANIM_MOVE=0,1 KKE_ANIM_CIRCLE=8 ./anim_demo   # walk in circles by itself

Variable	Effect
KKE_ANIM_MOVE=x,y	hold the move stick there (x right, y forward, -1 to 1): for checks without a controller
KKE_ANIM_CIRCLE=<s>	turn that stick round once every <s> seconds, through every direction of the blend space
KKE_ANIM_REST=1	start with "Show the rest pose" on
KKE_ANIM_MIRROR=1	start with the polished floor (with KKE_REFLECTIONS=screen, kke or classic it reflects the scene)
KKE_ANIM_GLASS=1	start with the glass block in front of the tentacles (with reflections on it bends what is behind it; KKE_REFRACTIONS=0 to compare)
KKE_ANIM_LIGHTS=n	start with n small coloured lamps over the floor, the many lights past the 16 key ones (clustered; KKE_CLUSTERS=0 walks them all, to compare; try KKE_MOOD=night)
KKE_ANIM_VIEW=d,p,y	start the camera d metres away at pitch p and yaw y (radians)
KKE_ANIMATIONS_DIR=<folder>	where to look for UAL1_Standard.fbx and UAL2.fbx
KKE_SKIP_INTRO=1	skip the logo intro (engine-wide)

Controls

Action	Keyboard / mouse	Controller
Move (the mannequin faces the camera's way)	WASD	left stick
Walk instead of run	the walk key of the character controls	the walk button
Turn the camera	left-drag	right stick
Zoom	wheel	d-pad
Settings panel	F3, or click	View

Rebindings are saved to anim_demo_input.json. The panel has the live blend weights, "Show the rest pose", and the tentacles' bend limit (8 to 60 degrees a joint) and damping (1 to 30 degrees a pass).

How it works

AnimDemoModule.cpp:

• loadCharacters() loads UAL1, adds UAL2's clips to the same skeleton (kke::appendClipsByBoneName), and spawns the mannequin. aPoseOf() makes the A-pose copies: the same model with each upper arm turned 45 degrees down at rest. The skin keeps its T-pose binding, so drawn at rest the arms hang down, as an A-pose character's do. Two kke::PoseRetargets copy the mannequin onto it, matchRest off and on.
• buildBlendSpace() lays the clips out by velocity in the character's own frame (x = right, y = forward, m/s): idle at the middle, the walk round it at 1.5 m/s every 45 degrees, the jog at 3.5 m/s ahead. The gradient band weights (polar: direction as an angle, speed as a length) change smoothly as the stick turns, so there is no pop between "strafe left" and "walk forward", and all weighted clips play at one shared phase so the feet never slide.
• steer() turns the stick into a velocity relative to the camera (running only ahead, walking sideways and back, the clips UAL has) and gives the blend space that velocity in the mannequin's frame.
• reach() runs kke::fabrikPoints on one tentacle and kke::ccdPoints with maxBendDegrees and maxStepDegrees on the other, and measures the sharpest bend of each the same way.

Make a game like this

A character that strafes while aiming (goblin_horde's heroes do this):

kke::BlendSpace2D space;
space.points = { { idle, { 0, 0 } }, { walkFwd, { 0, 1.5f } }, { walkLeft, { -1.5f, 0 } },
                 { walkRight, { 1.5f, 0 } }, { walkBack, { 0, -1.5f } } };
const int move = animator.addBlendState2D("move", space);
animator.play(move);
// every frame: the velocity in the character's frame
animator.setParameter2(glm::vec2(glm::dot(v, right), glm::dot(v, facing)));

A character from another pack playing your clips, whatever its rest pose: kke::retargetAnimations(ual, character, kke::matchBones(ual, character)) (rest matching is on by default). A tail or tentacle: keep its joints as points and call kke::ccdPoints(points, target, settings) each frame, with a bend limit per joint.

Files

File	What
main.cpp	the modules: input, UI, audio, orbit camera, models, the demo, its panel
AnimDemoModule.h / .cpp	the demo
game.json	the marketplace entry
engine/include/kke/Animator.h	BlendSpace2D, Animator::addBlendState2D
engine/include/kke/AnimRig.h	PoseRetarget, retargetAnimations, rest matching
engine/include/kke/ProceduralAnim.h	fabrikPoints, ccdPoints, CcdSettings