add new model and refactor

Author: reczkok

apps/typegpu-docs/public/assets/mesh-skinning/DancingBot.glb

@@ -0,0 +1,59 @@
+import type { Animation } from './types.ts';
+import { lerp, type Quat, slerp, type Vec3 } from './math.ts';
+
+export type NodeTransform = {
+  translation?: Vec3;
+  rotation?: Quat;
+  scale?: Vec3;
+};
+
+export const sampleAnimation = (
+  animation: Animation,
+  time: number,
+): Map<number, NodeTransform> => {
+  const transforms = new Map<number, NodeTransform>();
+  const loopedTime = time % animation.duration;
+
+  for (const channel of animation.channels) {
+    const { input: times, output: values } =
+      animation.samplers[channel.samplerIndex];
+    const components = channel.targetPath === 'rotation' ? 4 : 3;
+
+    let i = 0;
+    while (i < times.length - 2 && loopedTime >= times[i + 1]) {
+      i++;
+    }
+
+    const t0 = times[i];
+    const t1 = times[i + 1];
+    const alpha = t1 > t0
+      ? Math.max(0, Math.min(1, (loopedTime - t0) / (t1 - t0)))
+      : 0;
+
+    const start = i * components;
+    const end = (i + 1) * components;
+    const v0 = Array.from(values.slice(start, start + components));
+    const v1 = Array.from(values.slice(end, end + components));
+
+    const result = channel.targetPath === 'rotation'
+      ? slerp(v0 as Quat, v1 as Quat, alpha)
+      : lerp(v0, v1, alpha);
+
+    if (!transforms.has(channel.targetNode)) {
+      transforms.set(channel.targetNode, {});
+    }
+    const t = transforms.get(channel.targetNode);
+    if (!t) {
+      continue;
+    }
+    if (channel.targetPath === 'rotation') {
+      t.rotation = result as Quat;
+    } else if (channel.targetPath === 'translation') {
+      t.translation = result as Vec3;
+    } else {
+      t.scale = result as Vec3;
+    }
+  }
+
+  return transforms;
+};