Missile weapons are an important weapon system for combating the enemy’s depth and depth. They are indispensable weapons and equipment for modern warfare. The operation and training on real equipment is too costly and affected by the site and climate, and some special conditions (such as disaster consequences, emergency self-destruction, etc.) are difficult to achieve. Visual simulation [1] is the advanced stage of simulation animation, and it is also the most important form of virtual reality technology. It produces an immersive interactive simulation environment and enables users to directly interact with the virtual environment. Applying visual simulation technology to missile weapon equipment training, developing virtual training [2] and demonstration system, can give good real-time display of combat equipment training operations, giving people a strong visual impact, while the virtual operation has repeatable The advantages of operation, economy, efficiency, and safety make it easy to operate the trumpeter to understand missiles, quickly grasp the names and roles of various equipment agencies, and familiarize them with the operating methods and operating procedures, so that the training of weapons and equipment does not require a lot of manpower, material resources, and financial resources. Resources, in turn, can overcome the deficiencies of physical training due to time, space, and weather conditions. The visual simulation system of the missile weapon launch environment has a very significant role in strengthening the quality of operational trumpeters and improving the combat effectiveness of troops. In today's world, the field of solar energy appliacaiton is very important for human being. Belttt's solar power generation system can help people to use the solar energy better. Belttt has divide inverters into AC system and DC system. We are concentrate on off-grid Solar Power System, it makes us more professional. It's build-in inverter and Solar Controller, one piece of device is whole generation system. Solar Power Generator,Solar Generation System,Off Grid Solar Power System,Solar Lighting System Guangzhou City Poojin Electronic Technology Co., Ltd. , https://www.inverter-belttt.com
1 The composition of the simulation system
The missile launching environment is the process of launching guided missiles and their backgrounds. Different types of missiles are used to launch missiles of different types. In this paper, the visual simulation system is designed to simulate the guided missile missions and the launch command. After a certain type of ground-based mobile vertical launch missiles occupy the launch position and ground equipment from the launch vehicle, the missile launches the entire process from the scheduled launch. The user operates the computer mouse and keyboard, and the monitor displays the output firing process in real time, and the audio device outputs sound effects. According to the missile launch reality, the system needs to build the launch site environment, missile weapon system and missile model, vehicle model movement characteristics, missile upright and launch effects, sound output, etc., with the function of automatic roaming and multi-view observation along with the launch vehicle. Good real-time interaction. Therefore, it is necessary to implement the technology from two aspects: scene generation and function effect. Its system structure block diagram is shown as in Fig. 1.
Scene generation refers to the use of virtual reality technology to generate a simulated background environment, in which sky and terrain are necessary background elements. The model control includes the establishment, introduction, conversion, and display of weapon equipment entity models; in terms of the realization of functional effects, three-dimensional animation It refers to the vehicle's running and stopping in the virtual scene, the deployment of the ground equipment, the vertical launch of the missile, and the lateral push of the tailgate. The viewpoint transformation realizes the observation of the entire training process from multiple viewpoints and multiple angles. The special effects mainly include the simulation of the effects of explosion, flame, and smoke. The acoustic technology is the reproduction technology of various sounds in the scene. The human-computer interaction technology is used with the mouse and The keyboard controls the operation simulation software for playing and stopping, picking up and feedback.
2 key technologies for implementing sub-module functions [3]
On the Windows platform, the visualization system is based on Visual C++ 6.0 and OpenGL [4-5], combined with 3DS MAX modeling software and DirectSound programming design. Among them, Visual C + +6.0 as a powerful software development tool, MFC provides a logical structure for system development; as an application programming interface, OpenGL provides a function library, it is easy to achieve model control, viewpoint conversion, coloring, lighting, texture mapping, Interactive operation and animation; 3DS MAX modeling software is easy to use, easy to render, especially demonstrated by its ability to build models (mainly including subdivision surface technology, flexible selection, surface tools and NURBS technology, etc.); DirectSound is DirectX. The device used to control the sound and the components of the sound processing are fast and controllable. The DirectX sound processing function can be used to generate real-time sound effects when designing the visual system.
2.1 Scenario Generation The launch environment of a vehicle-launched guided missile is an outdoor open-air environment. The sky and terrain are necessary background elements for the missile weapon launch simulation system. The model construction is to call OpenGL library modeling; for missiles and launch vehicles and other entities, 3DS is used. MAX establishes its basic model and OpenGL loading entity model 3DS file, which has high modeling efficiency and can realize human-computer interaction.
2.1.1 Sky Background Using OpenGL to generate a sky background, there are usually three methods: (1) clear the background with a light blue that is close to the sky, and (2) a “sky box†that draws a cube and textures it ( SkyBox) method; (3) hemispherical sky model. For the outdoor sky background, the simple sky model and the “sky box†model with a blue clear background are simple and realistic. The earth is spherical, and the hemispherical sky model's effect matches the real world's sky and can simulate the sky effect that matches the real world. Therefore, this paper uses the hemispherical sky model. Use the spherical equation in math: 
In the formula, K is an arbitrary point on the sphere, x, y, and z are the coordinates of the point, and r is the radius of the sphere. Turn into a parametric equation F(r, φ, θ): 
After obtaining the coordinates of each point on the sphere from equation (2), the sky frame is drawn using the triangle strip (GL_TRIANGLE_STRIP) in OpenGL technology. Then apply the texture mapping technology to map the 3D sky cloud image with real effects.
2.1.2 Terrain Background Completion of terrain generation and generation of different geomorphological features (such as mountains, plains, highways, field terraces, etc.). There are mainly two ways to draw the terrain model: First, simulate the terrain according to the precise description of the terrain graphics data; Second, simulate the terrain in the natural scene. Simulation terrain can not only meet the needs of the design of this article, but also apply the fractal point theory to the midpoint displacement method, and achieve realistic virtual terrain with as little data as possible, which is both economical and practical. Therefore, the vision system adopts the latter and DS algorithm is selected. The algorithm is simple in calculation and fast in calculation. It can recursively generate a refined grid with arbitrary resolution, and it can also retain existing terrain measurement data. Based on the terrain model, 2D texture graphics are mapped to enhance the veracity of the terrain and obtain the effects such as mountains, plains, highways, and field floors required for the launch environment. Billboard technology enables fast and efficient simulation of trees.
2.1.3 Model Control Missile weapon systems and missiles are essential basic physical models for the visual simulation system. It is an ideal method to control the model which is generated by 3DS MAX and then import it into OpenGL program. The 3DS file is composed of many chunks (nested sub-blocks in large chunks), and one chunk consists of chunk information and chunk data. The block information, in turn, consists of the ID of the block and the length of the block. To read the solid model 3DS file completely, we must read the model vertex information, triangle surface information, texture information, and triangle surface texture information contained in these blocks. Create a virtual model class in the MFC project, use the OpenGL command to call the nested block structure of the 3DS file recursively, and return to the previous level (after reading the child block, return the parent block) is the condition of the currently read block byte The number is equal to the block length. Switching from the parent block to reading its child block can be done using the switch( ) statement.
2.2 Implementation of functional effects The realization of functional effects mainly completes the generation of static scenes, such as system roaming, different viewing angles, missile launch vehicle driving, missile erection and take-off, tail shroud push, and tail flame generation.
(1) Three-dimensional animation In the system scene, three-dimensional animation mainly includes the launch and stop of vehicles along the road surface, the deployment of ground equipment, the erection and vertical alignment of the missile along a fixed point, and the ejection of a missile at a given height at a given initial speed. Missile ignition. First call glutInitDisplayMode (... | GLUT_DOUBLE) function to enable double buffering, allocate two color buffers, foreground buffer for graphic display, background buffer to execute drawing commands. The drawing commands of the scene are first called in the background. When the complete picture is drawn in the background video, the SwapBuffers( ) function is executed to become the visible video buffer. The animation effect is obtained by setting the translation command glTranslate( ) and rotation command glRotate( ) in OpenGL. In this way, through the matrix transformation, the background drawing is completed and the foreground is displayed. The two buffer areas continuously reciprocate and finally obtain continuous images.
(2) Change of viewpoint In the missile launch process, a single point of view does not meet the requirements of the observer. The point of view has two meanings: First, as the vehicle travels and roams automatically, it observes the process of occupying the position. Second, it observes the ground equipment deployment and the missile launches from a different angle. First, call the OpenGL function gluViewport( ) to set the viewport to determine the position and size of the viewport; then use the gluPerspective( ) function to define the size and distance of the visible cone in the model's coordinate system. The gluPerspective() function has a crop function, in which objects inside the viewport cone are projected, and not inside the viewport cone are cropped by the six faces of their viewports. Then use the gluLookAt() function to set the viewpoint transformation in the view transform. Two relative viewpoints were designed for the vertical launch and the system was switched to observe the side view (right side of the launch vehicle) and tail view (back side of the launch vehicle) when the missile was launched vertically.
(3) Sound Simulation A complete simulation system requires not only images, but also sound, so as to produce audiovisual effects and reach the immersive feeling. Acoustic simulation provides auditory information. Using computer multimedia technology, simulation produces the realistic sound effects of missiles during transportation, erection, and launch. These sound effects include the sound of the transmitting vehicle (such as the roar of the engine, the horn sound), the sound of the missile upright, The sound of the generator and the sound effects of the firing. The acoustic simulation process includes digital sound acquisition, quality processing and effect playback. Through the on-site recording, the sounds of various situations in the missile weapon launch process are obtained. After sampling and filtering, a wave file that vividly reflects the system sound effects is formed. Invokes the powerful sound processing API functions provided by DirectSound to load the sound file in the application and release the sound at different times during program execution.
(4) Interaction Technology The interactive technology of the missile weapon launch environment visual simulation system designed in this paper includes keyboard interaction and mouse interaction. Keyboard interaction refers to the use of the message processing functions provided by the MFC program framework to receive keyboard actions, modify control variables to start, reset, pause, resume, terminate, and other controls. In the defined TimeFunction( ) function, the keyboard variables are set to achieve animation control. The mouse interaction includes two processes of picking and feedback (FeedBack). The left mouse button clicks on some important functional devices of the weapon system on the screen. The text on the screen shows the name, function, and operation mode of the instrument. Interaction technology provides a good platform for software operators. It shows the details of missile launches more intuitively and improves the interactive program code. It also provides a reference for the next development of the missile weapon virtual training system.
(5) Special Effects Special effects include the smoke and tail-flame effects produced when the missile is launched. The simulation of smoke effects consists of a series of images that are transparently processed and then blended with the background. By controlling the position and fusion parameters of the images, the effect of smoke drift and desalination can be achieved. The simulation of the tail flame effect uses a particle system, which is realized by generating elementary particles with independent life cycles and attributes and having the same or similar behavioral rules inside. A number of tiny particles with simple shapes and life are used as the basic elements, and objects are defined as many irregular, randomly distributed particles. With the passage of time, each particle has an independent life cycle and is randomized by particle parameters. With the control of the process, old particles are constantly disappearing, new particles appear constantly, and the effect of simulating the tail flame is achieved by imparting texture to the particles. The use of particle systems to achieve a high degree of fidelity.
3 Optimization Measures After the entire visual simulation system is set up, OpenGL illumination, material, texture mapping, and special effects technologies are applied to generate a realistic missile launch environment. However, the entire system needs to process more data and has a large amount of calculations. It is necessary to ensure that the software runs smoothly on ordinary PCs and that it can truly achieve cross-platform use and take optimization measures to solve the problems of image realism and real-time performance. The specific optimization measures are as follows:
(1) Double-buffering is enabled, the foreground manages the graphical display, and the drawing commands are executed in the background.
(2) Open OpenGL blanking function, do not draw back and occluded parts.
(3) Calling the display list The function statements listed in the list are executed in sequence. The display list is preprocessed and stored in the memory of some OpenGL composite operations. During the execution of the program, the composite operation that has been preprocessed in the memory is directly invoked to optimize program performance.
(4) After using the level of detail (LOD) technology, the distant scenes are relatively blurred, the nearness is clear and natural, and it is in line with the actual situation. It also reduces the amount of calculation and improves the rendering speed.
4 simulation results in the 3DS MAX to establish a basic solid model, in the VC++ and OpenGL development environment to achieve the simulation control of the event flow, the development cycle is short, high efficiency, and can achieve better simulation results. The virtual missile launch environment visual system of the above method of generating realized in a virtual environment missiles to the onboard transport means launch position, from missile vertical projectile shot, tail cover thruster and ignition process simulation, scenarios true matches the missile launches actual. At the same time, the effect is smooth, human-computer interaction is natural, and real-time sound effects are generated by matching acoustics. There is an immersive feeling and intuitive effects are added. The visual simulation system of the launching environment of guided missiles makes it easy and practical to implement, train, and observe missiles.
In this paper, the virtual simulation technology is applied to the computer software and hardware platform to construct the missile launch environment visual simulation system. The virtual vision system has the characteristics of high efficiency, controllability, non-destructiveness, flexibility of use, and low operating cost of the system. It can overcome the limitations of traditional training methods, and it not only performs missile operation simulation training for trumpeters, but also replaces live missile training. Some subjects and contents have changed the traditional methods of teaching people, teachers and followers to improve the quality of training. At the same time, they have a good reference for the development of the next missile virtual training system. The development and application of the virtual missile training system provides a new method for the missile force to improve and master the operation of the missile weapon system and quickly form combat capabilities.
references
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[2] Liu Yuhai, Li Rui, Zhang Xien. Design and Implementation of Missile Virtual Operation Training System. Aircraft Missiles, 2002, (8).
[3] Peace Dove Studio. OpenGL Advanced Programming and Visual Development System Development (2nd Edition). Beijing: China Water Conservancy and Hydropower Press. 2007.
[4] Wu Bin, Bi Liyun. OpenGL programming examples and techniques. Beijing: People's Posts and Telecommunications Press, 1999.
[5] WrightR S, Lipchak J B. OpenGL Super Collection (2nd Edition). Xu Bo, translated. Beijing: People's Posts and Telecommunications Press, 2005.