Inverse Kinematic Improvements

index.html

@@ -86,7 +86,6 @@
 		<script src="lib/GLTFExporter.js"></script>
 		<script src="lib/CanvasFrame.js"></script>
 		<script src="lib/canvas2apng.js"></script>
-		<script src="lib/fik.min.js"></script>
 		<script src="lib/molang.umd.js"></script>
 		<script src="lib/wintersky.umd.js"></script>
 
@@ -156,6 +155,7 @@
 		<script src="js/animations/animation_mode.js"></script>
 		<script src="js/animations/animation.js"></script>
 		<script src="js/animations/molang.js"></script>
+		<script src="js/animations/fabrik.js"></script>
 		<script src="js/animations/timeline_animators.js"></script>
 		<script src="js/animations/keyframe.js"></script>
 		<script src="js/animations/timeline.js"></script>

js/animations/fabrik.js

@@ -0,0 +1,81 @@
+function fabrikIter(bones, target, pole) {
+    let n = bones.length;
+    let bases = bones.slice(0, -1);
+
+    let distances = bases.map((bone, i) => {
+        return bone.distanceTo(bones[i + 1]);
+    });
+
+    let dist = bones[0].distanceTo(target);
+
+    polecalc: if (pole) {
+        let target_offset = target.clone().sub(bones[0]);
+        let target_dir = target_offset.normalize();
+
+        let tip_offset = bones[n - 1].clone().sub(bones[0]);
+        let tip_dir = tip_offset.normalize();
+
+        let tip_to_target_rotation = new THREE.Quaternion().setFromUnitVectors(tip_dir, target_dir);
+
+        let pole_offset = pole.clone().sub(bones[0]);
+        let pole_dir = pole_offset.projectOnPlane(target_dir).normalize();
+
+        if (pole_dir.length() == 0) {
+            break polecalc;
+        }
+
+        let normal = target_dir.cross(pole_dir).normalize();
+
+        if (normal.length() == 0) {
+            break polecalc;
+        }
+
+        bones.forEach(bone => {
+            let offset = bone.clone().sub(bones[0]);
+            offset.applyQuaternion(tip_to_target_rotation);
+
+            offset.projectOnPlane(normal);
+
+            offset.add(bones[0]);
+            bone.copy(offset);
+        });
+    }
+
+    if (dist > distances.reduce((partial, a) => partial + a, 0)) {
+        for (i = 0; i < n - 1; i++) {
+            let pos = bones[i];
+            let r = pos.distanceTo(target);
+            let lambda = distances[i] / r;
+            bones[i + 1] = pos.clone().multiplyScalar(1 - lambda).add(target.clone().multiplyScalar(lambda));
+        }
+    } else {
+        let b = bases[0];
+        let diff = target.distanceTo(bones[n - 1]);
+        const TOLERANCE = 0.001;
+        let max_iterations = 4_000;
+        while (diff > TOLERANCE && max_iterations > 0) {
+            bones[n - 1] = target;
+            for (i = n - 2; i >= 0; i--) {
+                let p = bones[i];
+                let p2 = bones[i + 1];
+                let r = p.distanceTo(p2);
+                let lambda = distances[i] / r;
+                bones[i] = p2.clone().multiplyScalar(1 - lambda).add(p.clone().multiplyScalar(lambda));
+            }
+
+            bones[0] = b;
+
+            for (i = 0; i < n - 1; i++) {
+                let p = bones[i];
+                let p2 = bones[i + 1];
+                let r = p.distanceTo(p2);
+                let lambda = distances[i] / r;
+                bones[i + 1] = p.clone().multiplyScalar(1 - lambda).add(p2.clone().multiplyScalar(lambda));
+            }
+
+            diff = target.distanceTo(bones[n - 1]);
+            max_iterations--;
+        }
+    }
+}
+