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7.2.1 Rendering quality

Rendering quality depends on such factors as geometry description, low−level graphics language, rendering hardware, and display hardware. Typically the only factor under the developer’s direct control is geometry description. The following will influence the visual appearance of rendered geometry:

Complexity of model description. Such complexity is usually defined in terms of the number of vertices or surfaces.

Application of different lighting and shading models. Lighting and shading models can be used to

influence perceived surface characteristics, such as smoothness of the model (Gauraud shading), or to add specular highlights to the model (Phong shading),

Complexity of texture images applied to the model. High−resolution texture images are less likely to

suffer from becoming pixelated when magnified.

Java 3D rendering settings. Java 3D and the lower−level graphics language compromise internally between speed and accuracy of rendering. There are settings to tell Java 3D to err on the side of speed or accuracy for everything from perspective calculation through to lighting and fog calculations.

Rendering quality is a difficult balancing act, and a compromise must typically be struck between the complexity of model description plus texture images on the one hand and rendering time on the other. It may be necessary to dynamically change the model description based on the distance of the object from the viewer using a level of detail approach.

Unfortunately, not all software and hardware renderers are created equal, and noticeable differences will be perceived between DirectX and OpenGL rendering as well as between different makes (and versions) of 3D accelerator cards and drivers. To compound matters, certain makes of 3D cards will incorrectly render certain configurations of geometric primitives. The only advice that can be given is to ensure applications are tested on as wide a variety of hardware and software platforms as possible.