2. Loading Scene Services

In the previous section, we’ve implemented to load a default scene. But it is not enough for the practical applications, where we need to load the actual data.

Data on the client mainly comes from the server, so in this section, we show the example about getting the needed scene from the server to explain how to load the scene and all the layers in the scene, in the next section we will show how to open a specified layer in the scene.

In the 3D system, a scene is equivalent to a map in the 2D system, and a layer in the scene is equivalent to a layer of a map in the 2D system. The main task of the 3D scene class (Scene) is to load the 2D and 3D map data. the 3D scene class (Scene) can be used to load the 3D layers (Layer3D) and terrain layers (TerrainLayer). A 3D scene object can contain multiple layers with Layer3D types and terrain layers TerrainLayer, which are managed by the 3D layer set and the terrain layer set TerrainLayers respectively.

In this section we describe how to use the 3D scene class (Scene) to load the scene services on the server.

Scene the 3D scene structure chart

Scene the common attributes

	Interface	Description
	camera	Gets or sets the camera object of the current scene, and a camera is equivalent to a view point.
	currentScale	Gets the scale of the current scene.
	flyingOperator	Obtains the fly operation object of the current scene. This attribute is primarily used to set the fly status of the scene, specify the fly direction to the next scene, control the fly pattern and animation.
	layer3Ds	Obtains the 3D layer set object.
	name	Gets or sets the name of the scene.
	sceneOption	Obtains the set of the visibility of the various interface elements in the scene, such as the longitude and latitude graticule, the atmosphere, etc.
	screenLayer3D	Obtains the screen layer in the scene.
	terrainExaggeration	Gets or sets the proportion of the terrain exaggeration which stretches the height of the terrain in a certain proportion.
	terrainLayers	Obtains the terrain layer set in the 3D scene.
	trackingLayer3D	Obtains the tracking layer in the scene.

Scene the common methods

	Interface	Description
	close	Closes all layers in the current scene which has been loaded in the 3D scene.
	findSelection3Ds	Finds the selection sets of the layers in the current 3D scene. This method returns the arrays of the Selection3D class objects, each Selection3D class object corresponds to all object sets which have been selected in a layer in the 3D scene, if no object is selected, the array is empty.
	getAverageFPS	Obtains the average number of frames to render the current scene.
	open	Opens a specified scene and all layers in the scene. when loading a specified scene, you need to load the environment variables at the same time, such as ambient light, background light, terrain exaggeration factor, camera, fog, sky, atmosphere, longitude and latitude lines, etc., and the layer data in the scene.
	refresh	Refreshes the 3D scene.
	resetTerrain	Resets the terrain layer. you need to call this function to refresh the terrain display when the terrain layers are added, deleted or set to be visible or invisible.
	save	Saves the current scene configuration as an XML file in GML standard, and uploads to the server.
	setRefreshRaster	Sets whether the real-time rasterization is refreshed. If there are display problems for the raster data in 3D system, this function can be called to refresh the display of raster data only.
	viewEntire	Zooms the 3D map scene to full extent.

SceneServicesList the structure chart of the scene service list information class

SceneServicesList the common attributes

	Interface	Description
	count	Obtains the total number of the scene services in the scene list.
	item	Obtains the scene service information with the specified scene index number (Nember type) or name (String type) in the scene list.
	serverAddress	Obtains the server addresses which provide the scene service list.

SceneServicesList the common methods

	Interface	Description
	load	Obtains all lists of the scenes services.
	removeAll	Removes all scene service information in the scene service list.

Obtain the scene services, and add all layers in the scene services

In the <body onLoad="onPageLoad()"> </body> of the "default.html" page, add the following code before the scene control, implement to add the server address input box and the scene service list which lists scene services provided by the specified server in the system interface:

JavaScript

JavaScript
<!--the information window-->`<div id="infoWindow" style=" left:0px; top:0px; width: 20%; visibility: visible; display: block; float: left; clear: both; cursor: auto; overflow: auto; position: relative; height: 100%; background-color:#B6D6EF; font-family: 仿宋_GB2312;">` <!--the server address input box-->`<p><label for="input">the server address: </label></p>` <!--the value after value is the requested server address in this line, this value needs to be modified according to the actual service by users-->`<p> <input id="ServerAddress" name="ServerAddress" type="text" value="http://localhost:8090/iserver/services/realspace-sample/rest/realspace" /> </p>` <!--the scene service list--> `<p><label for="sceneList" >the scene service list:</label></p> <p><select id="SceneList" name="SceneList" ></select></p> <p><input id="SceneLoad" type="button" value="load the scene" onClick="return SceneLoad_onclick()" /></p> <p><input id="SceneOpen" type="button" value="open all the layers" onClick="return SceneOpen_onclick()" /></p> </div>`

<!--the information window-->
<div id="infoWindow" style=" left:0px; top:0px; width: 20%; visibility: visible; display: block; float: left;
clear: both; cursor: auto; overflow: auto; position: relative; height: 100%; background-color:#B6D6EF; 
font-family: 仿宋_GB2312;">
<!--the server address input box-->
<p><label for="input">the server address: </label></p>
<!--the value after value is the requested server address in this line, this value needs to be modified according to the actual service by users-->
<p>
<input id="ServerAddress" name="ServerAddress" type="text"
               value="http://localhost:8090/iserver/services/realspace-sample/rest/realspace" />
</p>
<!--the scene service list--> 
<p><label for="sceneList" >the scene service list:</label></p> 
<p><select id="SceneList" name="SceneList" ></select></p>
<p><input id="SceneLoad" type="button" value="load the scene" onClick="return SceneLoad_onclick()" /></p>
<p><input  id="SceneOpen" type="button" value="open all the layers" onClick="return SceneOpen_onclick()" /></p>
</div>

Add the following code in the header of the "GettingStarted.js" file to declare global variables:

JavaScript
`var sceneAddress = null; var sceneName = null;`

Add the following code after the existed code, which is in the function body of the callback function initCallback after the controls in the "GettingStarted.js" file are initialized successfully, to obtain scene lists from the specified server:

JavaScript

JavaScript
`sceneAddress = document.getElementById("ServerAddress").value; var sceneServicesList = sceneControl.get_sceneServicesList();` //obtain the server address from the input box, and load the scene list on the server`var bLoad = sceneServicesList.load(sceneAddress);` //if the scene services are loaded successfully, then obtain the name of each scene `if (bLoad){var sceneList = document.getElementById("SceneList"); if (sceneList.length > 0){sceneList.length = 0;}` //obtain how many records in the scene list, indicating how many scene services provided by the server`var count = sceneServicesList.get_count();` //set out all the scene services provided by the server in the drop-down box of the scene service list`for(var i=0; i<count; i++){var oPtion = document.createElement("option");oPtion.value = sceneServicesList.get_item(i).get_name();oPtion.text = oPtion.value;` //the first scene service is selected by default `if (i == 0){oPtion.selected = true;}sceneList.options.add(oPtion);}}`

    sceneAddress = document.getElementById("ServerAddress").value;
    var sceneServicesList = sceneControl.get_sceneServicesList();
    //obtain the server address from the input box, and load the scene list on the server
    var bLoad = sceneServicesList.load(sceneAddress);
    //if the scene services are loaded successfully, then obtain the name of each scene                        
    if (bLoad)
    {
         var sceneList = document.getElementById("SceneList");
         if (sceneList.length > 0)
         {
              sceneList.length = 0;
         }
         //obtain how many records in the scene list, indicating how many scene services provided by the server
         var count = sceneServicesList.get_count();
         //set out all the scene services provided by the server in the drop-down box of the scene service list
         for(var i=0; i<count; i++)
         {
              var oPtion = document.createElement("option");
              oPtion.value = sceneServicesList.get_item(i).get_name();
              oPtion.text = oPtion.value;
              //the first scene service is selected by default 
              if (i == 0)
              {
                   oPtion.selected = true;
              }
              sceneList.options.add(oPtion);
         }
    }

When the users select a certain scene service in the interface, click the "Load Scene" button to load a specified scene. Add the following code at the end of the "GettingStarted.js":

JavaScript

JavaScript
`function SceneLoad_onclick() {` //obtain the server address in the input box `sceneNames = document.getElementById("SceneList");` //traverse all names of the scene services, and determine the name of the selected scene currently, then open the specified scene`for(var i=0; i<sceneNames.length; i++) { if(sceneNames.options[i].selected == true) { sceneName = sceneNames.options[i].value; alert("The "+sceneName+" on the "+sceneAddress+" is loaded!"); } } }`

function SceneLoad_onclick()
{ 
        //obtain the server address in the input box   
        sceneNames = document.getElementById("SceneList");       
        //traverse all names of the scene services, and determine the name of the selected scene currently, then open the specified scene
  for(var i=0; i<sceneNames.length; i++)
        {       
                if(sceneNames.options[i].selected == true)
                {
                        sceneName = sceneNames.options[i].value;
                        alert("The "+sceneName+" on the "+sceneAddress+" is loaded!");
                }
        }
}

After opening the specified scene service, click the "Open All Layers" button to open all layers in the specified scene. Add the following code at the end of "GettingStarted.js":

JavaScript
`function SceneOpen_onclick() { scene.open(sceneAddress,sceneName); }`

The following picture shows the visualization after opening the scene "Scene" which contains layers of vector, image, terrain, KML, etc.:
Figure 1 Open the scene

Figure 2 the various layers in the scene

2. Loading Scene Services

Overview

Scene the 3D scene structure chart

Scene the common attributes

Scene the common methods

SceneServicesList the structure chart of the scene service list information class

SceneServicesList the common attributes

SceneServicesList the common methods

Obtain the scene services, and add all layers in the scene services