Divine Staff of Archangel: put the glints along the staff, not across the wearer

src/controllers/actors/weaponSprites.test.ts

@@ -93,6 +93,39 @@ describe('a held weapon\'s sprites (RenderLinkObject, ZzzCharacter.cpp:7027-8386
     const sprites = new WeaponSprites(scene, object, [{ texture: 'impact03', bone: 0, scale: 0.75, light: [1, 1, 1] }]);
     expect(sprites.nodes[0].parent).toBe(root);
   });
+
+  it('ride bone 0 where a one-bone model keeps it, on its mesh node (the Divine Staff\'s row of glints)', () => {
+    const root = new Mesh('staff', scene);
+    const model = new TransformNode('model_staff', scene);
+    model.parent = root;
+    const shaft = new Mesh('shaft', scene);
+    shaft.parent = model;
+    shaft.position.set(0, -0.525, 0.409);
+    shaft.rotation.set(0, -Math.PI / 2, -Math.PI / 2);
+    const object = new ModelObject(scene);
+    object.load({ mesh: root, skeleton: null as unknown as Skeleton, animationGroups: [] as AnimationGroup[] });
+    const sprites = new WeaponSprites(scene, object, [
+      { texture: 'flare01', bone: 0, offset: [-180, -40, 0], scale: 2, light: [1, 0.3, 0.1] },
+      { texture: 'flare01', bone: 0, offset: [90, -40, 0], scale: 2, light: [1, 0.3, 0.1] },
+    ]);
+    root.computeWorldMatrix(true);
+    model.computeWorldMatrix(true);
+    shaft.computeWorldMatrix(true);
+    const ends = sprites.nodes.map(node => {
+      node.computeWorldMatrix(true);
+      if (!node.parent) throw new Error('a sprite node has no parent');
+      return Vector3.TransformCoordinates(node.position, node.parent.getWorldMatrix());
+    });
+    // The two glints sit on the shaft's own x axis, 40 cm off it, as BoneTransform[0] puts them.
+    const along = Vector3.TransformNormal(new Vector3(2.7, 0, 0), shaft.getWorldMatrix());
+    const step = ends[1].subtract(ends[0]);
+    expect(step.x).toBeCloseTo(along.x);
+    expect(step.y).toBeCloseTo(along.y);
+    expect(step.z).toBeCloseTo(along.z);
+    expect(sprites.nodes[0].parent).not.toBe(root);
+    sprites.dispose();
+    expect(scene.transformNodes.some(n => n.name === 'weaponBone0')).toBe(false);
+  });
 });
 
 describe('a held sprite gated on its wearer', () => {

src/controllers/actors/weaponSprites.ts

@@ -39,9 +39,13 @@ export class WeaponSprites {
     const gltf = model.gltf;
     this.#scene = scene;
     this.#meshes = gltf ? gltf.mesh.getChildMeshes(false) : [];
+    const boneZero = gltf && !gltf.skeleton ? this.#bakedBoneZero(scene, this.#meshes[0]) : null;
     const at = (bone: number, name = 'weaponSprite') => {
       const node = new TransformNode(name, scene);
-      node.parent = (bone >= 0 ? gltf?.skeleton?.bones[bone + 1]?.getTransformNode() : null) ?? gltf?.mesh ?? null;
+      node.parent =
+        (bone >= 0 ? (gltf?.skeleton?.bones[bone + 1]?.getTransformNode() ?? (bone === 0 ? boneZero : null)) : null) ??
+        gltf?.mesh ??
+        null;
       return node;
     };
     this.nodes = specs.map(spec => {
@@ -110,9 +114,37 @@ export class WeaponSprites {
     return false;
   }
 
+  /** The bone-0 frame of a model with no skeleton, when one was needed (disposed with the sprites). */
+  #boneZero: TransformNode | null = null;
+
+  /**
+   * A one-bone model comes without a skeleton: its bone's rest transform sits on the mesh nodes instead
+   * (the Divine Staff of Archangel's is turned -90/-90 and moved off the root). `BoneTransform[0]` is that
+   * frame, not the root, or the staff's row of glints lies across the shaft and through the wearer.
+   * Null when the mesh sits on the root as it is.
+   */
+  #bakedBoneZero(scene: Scene, mesh: AbstractMesh | undefined): TransformNode | null {
+    if (!mesh) return null;
+    const turned = mesh.rotationQuaternion
+      ? Math.abs(mesh.rotationQuaternion.w) < 1 - 1e-6
+      : mesh.rotation.lengthSquared() > 1e-12;
+    const moved = mesh.position.lengthSquared() > 1e-12;
+    const scaled = Math.abs(mesh.scaling.x - 1) + Math.abs(mesh.scaling.y - 1) + Math.abs(mesh.scaling.z - 1) > 1e-6;
+    if (!turned && !moved && !scaled) return null;
+    const frame = new TransformNode('weaponBone0', scene);
+    frame.parent = mesh.parent;
+    frame.position.copyFrom(mesh.position);
+    if (mesh.rotationQuaternion) frame.rotationQuaternion = mesh.rotationQuaternion.clone();
+    else frame.rotation.copyFrom(mesh.rotation);
+    frame.scaling.copyFrom(mesh.scaling);
+    this.#boneZero = frame;
+    return frame;
+  }
+
   dispose(): void {
     this.#sprites.dispose();
     for (const node of this.nodes) node.dispose();
     for (const node of this.#emitAt) node.dispose();
+    this.#boneZero?.dispose();
   }
 }