Caleb Won - Animation System

Animation System Features

Animation system made for implementing IK on Mixamo humanoid skeletal rigs
Basic animation state machine including idle, walking and grabbing states
Animation blending between multiple animation states and supporting joint masks
FABRIK based pose solving in 3D space on the legs of the skeleton for foot placement correction
FABRIK solving with constraints for arm reaching animation and constrained angle for the head turning.
Skeletal vertex skinning in HLSL for optimized animation rendering

Animation Pipeline Steps

Load pre-authored animation data including bind poses, local and world transforms for animation key frames and skeletal mesh data
Get the correct frame of animation as a baseline pose.
Analyze the current surroundings of the skeletal rig:
Raycast vs ground geometry to find grounded target positions
Checking if foot placement results in clipping on stairs
Predicting grounded foot locations based on current animation and input
Adjust the pose using animation data, context data and FABRIK solver
Send the final skinning matrices to the renderer for vertex shading
Render the final output of the corrected pose

FABRIK Joints

Using FABRIK, I created multiple different contstrained versions of the algorithm implementing different kinds of constraints
Angle constraints limit the first effector's angular direction to a conical range like a shoulder
Swing constraints lock the whole 2 bone chain to a plane simulating the movement of something like a knee. These can additionally be clamped to angular ranges.

Animation System Architecture

Skeletal animations are made up of key frames that hold an array of data for each bone in the animated skeleton
Bone data is comprised of position, rotation and scale represented as 3D vectors for position and scale and a quaternion for rotation. These are designed to be easier interpolated for smooth animation blending.
The animated skeleton is a structure that is put into a game and stores the current states of its own bones. These can be influenced by skeletal animation data and game code.
Outside of the immediate skeleton, simple features like animation blending and states are handled by classes like AnimationBlender and Animation system.

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