Genarrative/apps/ai-game-creator-shell/src/view/project-development/resourceModelScene.ts

import type * as ThreeTypes from 'three';

/**
 * 引擎三维模型的**共用场景能力**：加载、取景、释放。
 *
 * 卡片缩略图（`resourceModelThumbnail`）和交互式预览浮层（`ResourceModelViewer`）都走这里，
 * 避免出现「缩略图能打开、放大后打不开」这种两套加载逻辑的分叉 —— 格式支持面、取景算法和
 * 释放口径必须逐字一致。
 */
export type ResourceModelSource = {
  /** 预览管线给出的 blob URL（模型整份字节）。 */
  sourceUrl: string;
  /** `model/gltf-binary`、`model/gltf+json` 或 `application/octet-stream`（FBX）。 */
  mediaType: string;
};

export function isResourceModelFbx(source: ResourceModelSource) {
  return (
    source.mediaType === 'application/octet-stream' ||
    source.sourceUrl.toLowerCase().includes('.fbx')
  );
}

/**
 * 按媒体类型加载模型。
 *
 * 只支持**自包含**的模型：`.glb`、单文件 `.gltf`（buffer 内嵌）、`.fbx`。多文件 glTF
 * （`baseURI` 指向外部 `.bin` / 贴图）在 blob URL 下无法解析相对路径，加载失败由调用方
 * 降级成类型卡，不做静默半渲染。
 */
export async function loadResourceModelObject(
  source: ResourceModelSource,
): Promise<ThreeTypes.Object3D> {
  if (isResourceModelFbx(source)) {
    const { FBXLoader } = await import(
      'three/examples/jsm/loaders/FBXLoader.js'
    );
    return new FBXLoader().loadAsync(source.sourceUrl);
  }
  const { GLTFLoader } = await import(
    'three/examples/jsm/loaders/GLTFLoader.js'
  );
  const gltf = await new GLTFLoader().loadAsync(source.sourceUrl);
  if (!gltf.scene) {
    throw new Error('模型内容为空');
  }
  return gltf.scene;
}

/**
 * 把相机摆到能完整看见整个模型的位置，并返回模型中心与尺寸。
 *
 * 取景口径与 3D 软件一致：按包围盒最大边计算距离，留 35% 余量，从右上前方俯视。
 * 缩略图与交互预览共用同一条公式，尺寸窗口不同也不会出现「一边看得见、一边看不见」。
 */
export function frameResourceModelInCamera(
  THREE: typeof ThreeTypes,
  object: ThreeTypes.Object3D,
  camera: ThreeTypes.PerspectiveCamera,
) {
  const box = new THREE.Box3().setFromObject(object);
  const size = box.getSize(new THREE.Vector3());
  const center = box.getCenter(new THREE.Vector3());
  const maxDimension = Math.max(size.x, size.y, size.z);
  if (!Number.isFinite(maxDimension) || maxDimension <= 0) {
    throw new Error('模型几何尺寸无效');
  }
  const distance =
    (maxDimension / 2 / Math.tan((camera.fov * Math.PI) / 360)) * 1.35;
  camera.position.set(
    center.x + distance * 0.55,
    center.y + distance * 0.42,
    center.z + distance * 0.75,
  );
  camera.near = Math.max(distance / 500, 0.001);
  camera.far = distance * 20;
  camera.lookAt(center);
  camera.updateProjectionMatrix();
  return { center, size, maxDimension, distance };
}

/** 环境光照：半球光 + 一盏主光，保证没有材质贴图的模型也有体积感。 */
export function addResourceModelLights(
  THREE: typeof ThreeTypes,
  scene: ThreeTypes.Scene,
) {
  scene.add(new THREE.HemisphereLight(0xffffff, 0x445566, 2.2));
  const keyLight = new THREE.DirectionalLight(0xffffff, 2.0);
  keyLight.position.set(2, 3, 4);
  scene.add(keyLight);
}

/** 释放模型对象占用的几何、材质与贴图，避免反复开关预览时显存只涨不降。 */
export function disposeResourceModelObject(object: ThreeTypes.Object3D) {
  object.traverse((child) => {
    const mesh = child as ThreeTypes.Mesh;
    mesh.geometry?.dispose?.();
    const material = mesh.material;
    const materials = Array.isArray(material)
      ? material
      : material
        ? [material]
        : [];
    for (const entry of materials) {
      for (const value of Object.values(
        entry as unknown as Record<string, unknown>,
      )) {
        const texture = value as
          | { isTexture?: boolean; dispose?: () => void }
          | undefined;
        if (texture?.isTexture && typeof texture.dispose === 'function') {
          texture.dispose();
        }
      }
      (entry as { dispose?: () => void }).dispose?.();
    }
  });
}