Visualization Classes

These are classes used to present images of the model. These include the abstract classes Renderer and ColorMap. There are two steps in the creation of any graphical image: (1) create a model of the object to be displayed; and (2) render the model to an image that is viewed on the screen. The creation and rendering can be part of the same application, or can be split into two separate applications, where a 3d description of the model using a scene description language is o/p by the modeler and i/p by the renderer.

In our finite element work we have the model, the domain. Though the model we have is not typical, as it requires the displaying of scalar and vector quantities and not just rgb values. We need to develop an interface for the renderer. To do this we will introduce an abstract class Renderer which defines this interface. Doing this will allow full extensibility as it will allow concrete subclasses to be provided which may render the model to the screen, or generate an SDL file which can be read in by a rendering application or printed on a printer at a later stage.

The interface for the Renderer class we introduce will be very simple. It will only accept very simple primitive objects to be displayed (line and polygon). As such, the Renderer will not be required to render the components of the model, rather the components of the model will be required to display themselves. This will allow both the introduction of new component types, for example new element types, without existing Renderer classes being required to be rewritten and also new Renderer classes will be able to be introduced with the only requirement that they be able to display the primitive object types. The drawback of course is that the present design has to be modified to allow the components to display themselves. On the otherhand, as the objects can display themselves, it will allow complex images to be displayed, e.g. 3d beam elements with proper geometry and deformation along the length or beam with plastic hinges at ends could indicate amount of rotation at ends.