摘要：現(xiàn)在讓我們修改這個(gè)示例讓他可以展示兩個(gè)同項(xiàng)目但不同版號(hào)的模型及。示例執(zhí)行結(jié)果如下這邊是這個(gè)比較模型的括展代碼英文原文

熟悉 BIM360 Team 的朋友可能知道他有一個(gè)很牛的模型文檔版本比較的功能，但如果模型是放在 Google 云盤或是百度云盤上有可能做到嗎？

Autodesk Forge 團(tuán)隊(duì)先前寫了一個(gè)從 Google 云盤的轉(zhuǎn)檔示例，這個(gè)示例會(huì)從 Google 云盤里下載模型文檔到你的服務(wù)器上，在將它上傳到 Forge Data Management 服務(wù)上進(jìn)行轉(zhuǎn)檔，同時(shí)在轉(zhuǎn)檔完成后在瀏覽器上展示結(jié)果。

現(xiàn)在讓我們修改這個(gè)示例讓他可以展示兩個(gè)同項(xiàng)目但不同版號(hào)的 Revit 模型（model A 及 model B）。在 Forge Viewer 里，每個(gè) Revit 構(gòu)件都會(huì)對(duì)應(yīng)到一個(gè) dbId，而這個(gè) dbId 也會(huì)對(duì)應(yīng)到一個(gè) Reivt 唯一碼（Unique GUID），這個(gè)唯一碼也是 Forge Viewer 的外部編碼（Extenal Id），所以只要在 model A 及 model B 里比對(duì)兩者間有沒(méi)有不存在的 Extenal Id，以及比對(duì)同一個(gè) External Id 的構(gòu)件屬性里有沒(méi)有被新增、修改及刪除的參數(shù)，根據(jù)這個(gè)思路我們可以將沒(méi)有修改的構(gòu)件隱藏起來(lái)，有異動(dòng)的構(gòu)件以綠色（新增的）、紅色（刪除的）及橘色（有修改的）來(lái)上色，就可以在 Forge Viewer 上做出簡(jiǎn)單的模型比較功能，原代碼可以參考這里，示例可造訪這里。

示例執(zhí)行結(jié)果如下：

這邊是這個(gè)比較模型的括展代碼：

function VersionChanges(viewer, options) {
  Autodesk.Viewing.Extension.call(this, viewer, options);
}

VersionChanges.prototype = Object.create(Autodesk.Viewing.Extension.prototype);
VersionChanges.prototype.constructor = VersionChanges;

VersionChanges.prototype.load = function () {
  var modelA = this.options.modelA;
  var modelB = this.options.modelB;

  var removed = {};
  var added = {};
  var modified = {};

  var red = new THREE.Vector4(1, 0, 0, 1);
  var green = new THREE.Vector4(0, 0.5, 0, 1);
  var orange = new THREE.Vector4(1, 0.6, 0.2, 1);

  viewer.addEventListener(Autodesk.Viewing.OBJECT_TREE_CREATED_EVENT, function () {
    listElements(function (listA, listB) {
      // make all elements as ghost
      viewer.isolate(-1);
      viewer.clearThemingColors(modelA);
      viewer.clearThemingColors(modelB);

      for (var extIdA in listA) {
        if (listB[extIdA] != null) continue;
        var dbIdA = listA[extIdA].dbId;
        removed[extIdA] = dbIdA;
        console.log("Removed dbId: " + dbIdA);
        viewer.impl.visibilityManager.show(dbIdA, modelA);
        viewer.setThemingColor(dbIdA, red, modelA);
      }

      for (var extIdB in listB) {
        if (listA[extIdB] != null) continue;
        var dbIdB = listB[extIdB].dbId
        added[extIdB] = dbIdB;
        console.log("Added dbId: " + dbIdB);
        viewer.impl.visibilityManager.show(dbIdB, modelB);
        viewer.setThemingColor(dbIdB, green, modelB);
      }

      for (var extId in listA) {
        if (typeof listB[extId] === "undefined") continue; // removed dbId

        var dbId = listA[extId].dbId; // should be the same as listB[extId]
        var propsA = listA[extId].properties;
        var propsB = listB[extId].properties;

        for (var i = 0; i < propsA.length; i++) {
          if (propsB[i] == null) continue;
          if (propsA[i].displayCategory.indexOf("__")==0) continue; // internal properties
          if (propsA[i].displayValue != propsB[i].displayValue) {
            console.log("Property " + dbId + ": " + propsA[i].displayName + " changed from "
              + propsA[i].displayValue + " to " + propsB[i].displayValue);
            modified[extId] = dbId;
          }
        }

        if (typeof modified[extId] != "undefined") {
          console.log("Modified dbId: " + dbId);
          // color on both models
          //viewer.impl.visibilityManager.show(dbId, modelA);
          //viewer.impl.visibilityManager.show(dbId, modelB);
          viewer.setThemingColor(dbId, orange, modelA);
          viewer.setThemingColor(dbId, orange, modelB);
        }
      }
    });
  });

  function listElements(callback) {
    getAllLeafComponents(modelA, function (modelAdbIds) {
      getAllLeafComponents(modelB, function (modelBdbIds) {
        // this count will help wait until getProperties end all callbacks
        var count = modelAdbIds.length + modelBdbIds.length;

        var modelAExtIds = {};
        modelAdbIds.forEach(function (modelAdbId) {
          modelA.getProperties(modelAdbId, function (modelAProperty) {
            modelAExtIds[modelAProperty.externalId] = {"dbId": modelAdbId, "properties": modelAProperty.properties};
            count--;
            if (count == 0) callback(modelAExtIds, modelBExtIds);
          });
        });

        var modelBExtIds = {};
        modelBdbIds.forEach(function (modelBdbId) {
          modelB.getProperties(modelBdbId, function (modelBProperty) {
            modelBExtIds[modelBProperty.externalId] = {"dbId": modelBdbId, "properties": modelBProperty.properties};
            count--;
            if (count == 0) callback(modelAExtIds, modelBExtIds);
          });
        });
      });
    });
  }


  function getAllLeafComponents(model, callback) {
    var components = [];

    function getLeafComponentsRec(tree, parentId) {
      if (tree.getChildCount(parentId) > 0) {
        tree.enumNodeChildren(parentId, function (childId) {
          getLeafComponentsRec(tree, childId);
        });
      }
      else
        components.push(parentId);
      return components;
    }

    var instanceTree = model.getInstanceTree();
    var allLeafComponents = getLeafComponentsRec(instanceTree, instanceTree.nodeAccess.rootId);
    callback(allLeafComponents);
  }

  return true;
};

VersionChanges.prototype.unload = function () {
  return true;
};

Autodesk.Viewing.theExtensionManager.registerExtension("Autodesk.Forge.Samples.VersionChanges", VersionChanges);

英文原文：https://forge.autodesk.com/bl...