Using the OpenInventor Renderer

Introduction

After having read this chapter you will be familiar with:

Renderer modules in general
the user interface of the Renderer
Mouse interaction modes

In the previous chapter you have read about some basic steps in working with COVISE. You have already learned how to load a prepared module network. In this chapter we introduce some functionalities of the OpenInventor Renderer and their main usages. COVISE comprises other render modules as well but the OpenInventor Renderer can be seen as the default desktop renderer. OpenInventor is a high level object oriented graphics toolkit developed by Silicon Graphics. It uses OpenGL, the 3D graphics standard, as its rendering interface.

You can regard the Renderer as a movable window to a virtual world. The displayed scenario contains objects which are typically visual representations of simulation data. Depending on the selected visualization method you can have different visual representations for the same dataset. This allows to explore the various aspects and characteristics of a dataset and detect features otherwise not seen. In addition to the mapping of data to visual representations supportive geometries, such as bounding surfaces or reference geometries of machineries provided via CAD models can also be included in combination with the data visualizations. A typical example would be the visualization of a pressure distribution in a combustion chamber of a car engine. Such scenarios can be further examined with all the possibilities that the Renderer provides.

The Render Module

**Figure:** The Renderer Module Icon

Figure 2.1 : The Renderer Module Icon

At the end of a module network processing chain there is an output module, which in most cases will be a render module to visualize resulting data. Other output modules are write modules for saving results to disk or a special plot module for xy- charting. In the MapEditor working area those output modules are typically placed at the bottom of the map. Output modules normally have input ports only (blue rectangle on the left top of the render module in Figure 2.1).

The module selection and the usage of ports to build module networks will be described in the following chapters

The User Interface

In Figure 2.2 you can see the OpenInventor Renderer as it will appear on your desktop after you have inserted the Renderer module in the module placing area.

The renderer window consists of three major parts:

the menubar
the information area
the viewer area.

The menubar will only be explained shortly. It provides functionalities such as saving the current scene to a file or printing the scene. You can also adjust viewing parameters or set material and light properties using the menus. The information area provides information about the current state of the renderer. Beside some text fields for collaboration status there are two list boxes. The ColorMaps list box contains all the colormaps used in the visualization pipeline. The GeometryObjects list box contains all the geometry objects currently displayed. The viewer area holds the main viewer widget where the objects are displayed. The viewer area contains also other user interface elements.

**Figure:** The Renderer User Interface

Figure 2.2: The Renderer User Interface

Figure 2.3 shows the toolbar at the right side of the viewer area in greater detail. One feature of the toolbar is the home position. It represents the special camera position and orientation of an initial view. By pressing the home position button in the toolbar the camera will switch to the position and orientation of the viewers home position. With the set home position button you can set these values at any time.

**Figure:** The Toolbar

Figure 2.3: The Toolbar

Another feature of the toolbar is the view all button. Pressing this button causes the Renderer to adjust the camera position and orientation to view all objects.

Pressing the seek mode button changes the cursor to the seek mode symbol. Within this mode you can click on any part of your geometry. This will set the camera position in a way, that the selected point will be in the center of the window with a view orientation orthogonal to the object.

The button on the bottom of the toolbar selects a projection mode. By pressing this button you can switch between a perspective and an orthogonal projection. The default projection mode is the perspective one.

Arranged at the bottom of the viewer area are some user interface elements for rotating and zooming the camera. On the left side are two thumb wheels to rotate the camera about the x (Rotx) and the y (Roty) axis.

On the right side is a slider (Zoom) and a thumb wheel (Dolly) to zoom the camera.

Mouse Interaction Mode

The OpenInventor Renderer knows two fundamental interaction modes of the mouse:

The view mode transforms mouse interactions in viewpoint changes and the pick mode is used to change the properties of geometric objects. An active view mode is indicated by an active view mode button in the toolbar on the right side of the window. Also the cursor changes to a hand symbol. Within this mode you can rotate the whole scene about its center using the left mouse button. Move the mouse pointer over the geometry, press the button and move the mouse in that direction you want to rotate to. By releasing the button without moving the mouse simultaneously, the scene will be rendered from the new viewpoint. When you drag the mouse and release the button while you are moving, the scene will spin permanently until you click into to the viewer area. This continuation of the last transformation operation after mouse button release only works with rotations. Using the middle mouse button you can pan the scene. Using the combined left and middle button you can zoom the viewpoint in the same manner. Thus, dragging the mouse to the bottom of the window with the left and middle mouse button pressed, you will zoom into the scene. Dragging to the top will zoom out.

The pick mode is indicated by an active pick button in the toolbar and the cursor changes to an arrow. In this mode you can select individual geometries for further manipulations. By clicking with the left mouse button on a geometry object you select the geometry. The selection will be indicated by a bounding box (a red wireframed box) around that object. For the selection of multiple objects hold down the shift key while selecting the different objects. To remove the selection of the object just select the object again. To remove the whole selection click on any free part of the viewer widget. This working method is just the same you already know from popular drawing programs.

By clicking with the right mouse button into the viewer area in any of the two interaction modes a popup menu appears. This popup menu will not be further explained here. It provides many functionalities you find on the menubar too.

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Authors: Martin Aumüller, Ruth Lang, Daniela Rainer, Jürgen Schulze-Döbold, Andreas Werner, Peter Wolf, Uwe Wössner

COVISE Version 2021.12