2012

checkered background. Though not interactive, the preview will show
how the material will look when rendered photorealistically.
■ Click Active Preview
to get an OpenGL interactive preview of
the material on the standard ball against checkered background. This
is updated interactively while you change the parameters. The preview
will resemble the quality of material shown in Autodesk Navisworks
during navigation, but the quality will not be as high as the
photorealistic render.
■ Click Main Window Preview
to close the preview window in
the Material Editor and instead preview the material on the item
in the Scene View. This is updated interactively while you change
the parameters. The preview will be represent the material shown in
Autodesk Navisworks during navigation, but the quality will not be
as high as the photorealistic render.
4 For a simple material, there is only a single Material tab on the
Material Editor, whereas for a texture material, whether procedural
(generated from an algorithm) or bitmap (generated from an image),
there is an extra tab called Texture.
■ The Material tab contains simple parameters that affect the
material’s color, scale, shininess and so on. In the case of the Breeze
Block, there are parameters for the overall scale of the material, as
well as a block’s width and height, the block’s color and mortar color,
its roughness and reflectivity. For bitmap textures, you need to define
the location of the image in the Image File Name box. On a glassy
material, other factors would affect the transparency and refraction
properties of the glass. Some of these factors will not be apparent in
the interactive OpenGL window and will have to be rendered with
the Render to be seen.
■ The Texture tab contains parameters that specifically affect a texture
material’s texture mapping properties, such as its rotation, offset
(origin) and S- and T- (sometimes called U- and V-) scales. These
parameter values are applied in relation to an origin point (see
Ad-
vanced Materials
(page 561) for more information). There are S- and
T- Reflect check boxes, which will show the reflection of the image
in either (or both) of these axis. Finally there is an Offset Center
check box, that repositions the origin to the center of the image
(again, see Advanced Materials (page 561) for more information).
When using the Main Window Preview, texture changes can be
made instantly allowing interactive positioning of materials on an
object.
Use Presenter Materials | 559