Create Blender bones and animate and import with Assimp

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Here is the Youtube video showing the steps involved:

Here is a corresponding step-by-step procedure to create a proof-of-concept kinematic chain in Blender

You can use the LWJGL Assimp Java library to import the animations into Clojure as follows:

(import '[org.lwjgl.assimp Assimp AIAnimation AINodeAnim])
(def scene (Assimp/aiImportFile "test.gltf" (bit-or Assimp/aiProcess_Triangulate Assimp/aiProcess_CalcTangentSpace)))
(.mNumAnimations scene)
; 2
(def animation (AIAnimation/create ^long (.get (.mAnimations scene) 1)))
(/ (.mDuration animation) (.mTicksPerSecond animation))
; 10.4166669921875
(.mNumChannels animation)
; 5
(map #(.dataString (.mNodeName (AINodeAnim/create ^long (.get (.mChannels animation) %)))) (range (.mNumChannels animation)))
; ("Sphere" "Armature" "Stay IK" "Lowe Bone" "Upper Bone")
(def node-anim (AINodeAnim/create ^long (.get (.mChannels animation) 4)))
(.dataString (.mNodeName node-anim))
; "Upper Bone"
(.mNumPositionKeys node-anim)
; 2
(.mNumRotationKeys node-anim)
; 250
(.mNumScalingKeys node-anim)
; 2
(def quaternion (.mValue (.get (.mRotationKeys node-anim) 249)))
[(.w quaternion) (.x quaternion) (.y quaternion) (.z quaternion)]
; [0.99631643 -1.20924955E-17 -1.5678631E-17 0.08575298]
(/ (.mTime (.get (.mRotationKeys node-anim) 249)) (.mTicksPerSecond animation))
; 10.4166669921875

I used tmux, Clojure with rebel-readline, and vim with vim-slime to do the coding.

For an in-depth introduction to rigging I can recommend Mark Alloway’s video on how to rig and animate a landing gear.