True 3D visualization simulation and its implementation technology for remote applications

2 True 3D Visual Simulation Technology Based on J2EE
2.1 J2EE Technology for Platform Construction
J2EE is a system platform based on component-container model. It has become the mainstream of system construction and development with its advantages of flexibility, scalability, modularity, cross-platform and cross-database.
In this study, components mainly include Applet components running on the client and Web components and EJB components running on the server; containers mainly provide operating environment for these three types of components, such as JRE, JVM and Web Server.
(1) System flow based on J2EE. According to the specification of J2EE platform, the main steps of J2EE system flow are as follows: ① After the user starts the browser on the client, the user downloads the HTML page dynamically generated by JSP from the Web server, and realizes the browsing and query functions of the system by interacting with the Applet program embedded in the page; ② After receiving the user request from the client, the Web Server container of the Web layer parses the corresponding JSP or Servlet component to generate HTML page for the client to use; ③ After receiving the business request in the Web layer, the business layer container provides the information to the EJB component and the database adapter component, and completes the support for the Web layer components through the business domain code constructed by these two components; ④ The database server in the data layer provides the required data support for the components in the business layer, and also provides management and maintenance for various engineering data of the geological and mining engineering system.
(2) System design based on J2EE. In the client layer, the system uses JRE as a Java plug-in embedded in the browser as the Applet client running environment, uses Applet to realize the interaction between people and the system, and uses JOGL to realize the three-dimensional visualization of the engineering system based on Web. In the Web layer, Struts is used to realize the business logic control function, JSP components are used to dynamically generate pages, and the Web server Tomcat is used to provide services for the Web layer components. In the business layer, EJB technology and JavaBean are used to construct implementation classes and establish engineering system models.
In actual research, considering the fact that the engineering system has a large amount of numerical calculations such as sampling data processing and data normalization processing, and massive data throughput such as graphic data processing, driver interface technology is used for database operations to cope with the high database access speed requirements.
2.2 User interaction Applet technology
Applet is an application written in Java language, which can be embedded in the browser to obtain peripheral information such as mouse and keyboard, and respond to events. The life cycle of Applet includes four stages: initialization, start, run and end. During this process, the support of Java runtime environment is always required.
(1) Applet technology features. In the Web browser environment, HTML files load Applet programs and related resources through Web services. When the file is created, the embedded Applet program starts to run, and when the file is closed, the Applet program also ends. Applet programs can not only use window environment development tools to establish standard graphical interfaces to realize human-computer interaction, system query and other functions, but also support JOGL and other technologies for displaying and transforming three-dimensional graphics. Since Applet programs are accessed based on the network, they have potential security risks.
(2) Applet system design. In the actual design process, the subclass of the Applet class, JApplet, is used to complete the functions of the Applet, so that users can communicate with the system by clicking the mouse, tapping the keyboard, and other activities. The GLCanvas class in the JOGL class library is used to set the JOGL graphics display parameters and process the user events obtained by JApplet to realize the combination of JOGL and JApplet. The CG, GL and other classes in the JOGL class library are used to draw the three-dimensional graphics of the engineering system, and the rotation, translation, cropping and lighting setting of the graphics are realized through the interface program. In terms of security, the digital signature tool of JDK1.2 is used to set the security of the Applet program, and the security of the program is realized by comparing the digital signature loaded on the network with the digital certificate held by the client.
2.3 JOGL technology for three-dimensional drawing
At present, the more popular three-dimensional visualization tools based on Web browsers include VRML, X3D, Java3D and JOGL based on Java language. Although VRML and X3D can both generate interactive virtual reality scenes, they are still data files in essence and lack direct support for visualization algorithms. Java3D and JOGL based on Java can not only support scene graphics processing like VRML and X3D, but also support higher-level graphics processing.
(1) JOGL graphics rendering technology. JOGL is a technology based on the OpenGL public graphics interface. It is a recognized Java binding to OpenGL and is jointly supported by Java creator SUN and OpenGL creator SGI [2]. This enables the three-dimensional simulation model of the engineering system developed using Java to integrate window interfaces such as AWT and Swing, while obtaining powerful 3D graphics rendering capabilities with direct hardware support.
(2) System design based on JOGL. This study selected JOGL as the implementation method of 3D visualization simulation technology for engineering systems based on B/S structure. Its core working process includes: calling GLDrawablefactory class to create GLDrawable object; using createGLCanvas() method in GLDrawable class to create GLCanvas object; calling GLCanvas corresponding method to generate GL object; calling GL corresponding method and setting properties to set and draw 3D display, etc.; adding event listening interface to GLCanvas to realize user response to GLCanvas object action, and overloading corresponding methods to realize mouse and keyboard control, so as to realize human-computer interaction.
3 Implementation of true 3D visualization simulation based on J2EE
Taking the engineering data of an underground mine as an example, this study uses the above system framework and technical methods to realize the true 3D visualization simulation system of geological and mining engineering based on B/S structure and J2EE platform, including 3D visualization simulation of surface terrain, ore body, shaft and tunnel engineering, as shown in Figure 2.