Material

The Material menu cell in the Matter module allows you to define surface material attributes for objects, polygons, or hierarchical branches of objects.

For information about applying material, see the Materials chapter in the Defining Materials and Textures User's Guide.

When you choose this menu cell, the Material Editor dialogue box is displayed.

Parameters

Select Material

Allows you to access and load previously saved material files using the Database browser. The browser opens to the current MATERIALS chapter.

When you select a file from the chapter, its name appears in the Material text box beside the Select button. You can change the name of the file in this text box if you like, such as for making edits to the parameters and saving it with a new name.

Shading Model

Defines how an object reacts to the light sources in terms of shading. There are five shading models: Blinn, Phong, Lambert, Constant, and Shadow Object.

Blinn

The Blinn shading model uses four characteristics: diffusion, specularity, eccentricity, and refractive index. This produces virtually identical results to the Phong shading model except that the shape of the specular highlight reflects the actual lighting more accurately when there is a high angle of incidence between the camera and the light, which is useful for rough or sharp edges. The specular highlight also appears brighter.

Phong

Phong is the default shading model. It uses three areas of illumination: ambient, diffuse, and specular. The result is a smoothly shaded object with diffuse and ambient areas of illumination on its surface, and a specular highlight so that the object appears shiny like a billiard ball. Reflectivity, transparency, refraction, and texture can be applied to an object shaded with Phong.

Lambert

The Lambert shading model deals with the intensity of reflected light. Two illumination areas are defined on the object's surface: ambient and diffuse. The result is a smoothly shaded object using a minimum of polygons. The object's surface appears as a dull matte finish with diffuse and ambient illumination, like an egg or a ping-pong ball. Reflectivity, transparency, refraction, and texture can be applied to an object shaded with Lambert.

Constant

The Constant shading model considers the object as being evenly lit. Only the diffuse shading area is used to colour the object. Reflectivity, transparency, refraction, and texture can be applied to an object shaded with Constant. The result is an object whose surface appears to have no shading at all, like a paper cut-out.

Shadow Object

The object is not visible in the rendered image. Instead, it is used as a support for a transparency map to cast coloured light and shadows on other objects. This shadow model can be used on numerous objects to create complex shadow patterns.

Note:
With the mental ray renderer, the shadow object property is decided by the model's global material, not the local material.

Specular

Allows you to define colour values for the specular highlight on a Phong or Blinn-shaded object. Colour values, ranging from 0 to 1, can be set numerically with the Colour sliders or with the Palette. Values can exceed 1, going as far as 10,000 in certain situations (such as when reflectivity or transparency are applied).

Ambient

Allows you to define colour values on the object surface area that is shaded with ambient light, an indirect overall illumination. Colour values, ranging from 0 to 1, can be set numerically with the Colour sliders or with the Palette. This parameter is active on objects shaded with Lambert, Blinn, or Phong.

Diffuse

Allows you to define colour on the surface area of the object that is diffusely illuminated by the light sources. Colour values, ranging from 0 to 1, can be set numerically with the Colour sliders or with the Palette. Diffuse colour must be defined for all shading models.

Colour Sliders

The Colour sliders provide a fast and accurate way of entering numerical values for colour components in the colour mixing triangle.

They allow you to define the colour values, ranging from 0 to 1 for the selected area of illumination (specular, ambient, and diffuse). The RGB button above the sliders toggles between the RGB, HLS, and HSV colour models. For more information on these colour models, see Palette.

Palette

Displays the Palette dialogue box which allows you to use the system palettes for selecting and mixing colours. For more information on using the palette, see Palette.

Incoming Colour

Select a colour in the appropriate dialogue box, then click Palette. The edited colour appears in the Incoming Colour box. You can now add this colour to your palette.

Choose an entry in the palette to be replaced by the incoming colour and click on this entry.

The Set fg and Set bg buttons allow you to transfer the edited colour to the foreground or background entry.

Display Box

This box shows the effect of all material parameters you set on a spherical object.

mental ray

If you're rendering with mental ray, you can select one or all of the mental ray shader types (Volume, Material, or Shadow). These options display a Shader dialogue box in which you can choose and activate material surface, volume, or shadow shaders for a given material.

For a description shaders, see the Using Shaders section of the Rendering User's Guide.

Since there are three shader types available, you must select the shader option you want before you click Edit.

• Material Shader gives you access to matter surface shaders, which are used to define the effect of light and colour on an object's surface.
• Volume Shader gives you access to volume shaders, which are used to modify rays as they pass through an object. Volume shaders allow you to easily simulate effects such as cloud, smoke, and fire.
• Shadow Shader lets you define the way in which an object's shadow is cast, such as its opacity and colour. The shader determines how the light coming from a light source is altered when it hits an object.
• Select: After a shader has been selected, click Select, below the shader options, to open the Load browser for the selected type of shader.

Select the shader from the database and click Load. The shader name appears in the text box below the appropriate Shader option.

If you need to search for a shader, double-click the .. (two dots) at the top of the browser and select the appropriate chapter.

• Edit: If you want to save the shader by another name and then edit the parameters, you can modify its name in the text box in which it appears. This creates a new shader with the new name, but with the current parameters. To edit the shader's parameters, click Edit, which displays the dialogue box containing the shader's parameters which you can edit.

For more information on material shaders, see the Using Material Shaders section of the Defining Materials and Textures User's Guide.

Custom Shader Ball

If you would like to preview the texture or material that you have chosen before accepting it, you can do so with the Custom Shader Ball.

To access the Custom Shader Ball dialogue box, select a texture or material, and click Edit in the mental ray area.

To access the shader ball, the following two buttons must be available: Auto and Preview.

Click Auto and then click Preview. A small dialogue box with the Custom Shader Ball appears with the texture or material that you have chosen.

You can also change parameters in the dialogue box.

To remove the Custom Shader Ball, click Ok.

Note:
If you don't want to preview the Custom Shader Ball, just click Refresh to one see the Custom Shader Ball; it is not previewed.

The new shader can then be saved and recalled by name in other scenes.

Specular Decay

Allows you to control the spread of the specular decay over the object surface (Phong and Blinn-shaded objects only). Values range from 0 to 300.

Reflectivity

Controls the reflectivity of the object. Values range from 0 to 1, with 0 being non-reflective and 1 being completely reflective (mirror). If reflectivity is assigned, it is necessary to overcompensate the specular values by drastically raising their values. For example, a specular highlight that was 1 on a non-reflective object could be reset to 1000. If an object's material is fully reflective, its other material attributes are not visible at all, so reflectivity should always be set to a value less than 1.

Transparency

Controls the transparency of the object. Values range from 0 to 1, with 1 being completely transparent. For a transparent material such as glass, a value of 0.9 is more convincing. If transparency is assigned, it may be necessary to overcompensate specular values.

Refractive Index

Controls the bending of light rays through a transparent material. The refractive index varies according to the nature of the transparent material desired (the refractive index of glass is around 1.33). The default is 1, which is the refractive index of air, allowing light rays to pass straight through a transparent material without distortion.

Static Blur

Blurs a spherical object to make it appear fuzzy or glowing. Select the Blur option to activate static blur.

Static blur is particularly well suited for spherical objects or objects with relatively continuous surface normals. If static blur is to be used on an object with non-continuous surface normals, such as a cube, it is recommended that the cube be bevelled to reduce the discontinuity of the surface normals.

• Width enlarges the object.
• Decay controls the rate at which an object becomes transparent. As the decay value increases, the object becomes transparent from its centre more quickly. Blur decay causes the object to become smaller as the decay is increased. To offset this effect, you can increase the Width parameter, which enlarges the object.

Preview

Allows you to render the selected object without exiting the Material Editor dialogue box. Make sure to select the appropriate renderer in the Preview Setup dialogue box (choose Preview->Setup).

Key

Allows you to save the current parameter settings as a keyframe for material animation. Parameters that can be keyframed are displayed with a double border. Without exiting this dialogue box, you can use the time line pointer to change the current frame to set other keyframes.

Save

Saves the current material setup into a material file using the Save Materials dialogue box.

Delete

Deletes the current material from the selected object and resets it to the default. If the object is part of a hierarchy, it inherits the materials of the parent.

Cancel

Cancels modifications made to a material since the dialogue box was opened, and exits the dialogue box.

Ok

Assigns the current material settings to the selected object. You must save the object to keep the new material assignment.

Tip:
You can also access the material editor from the Schematic window in the Matter mode by selecting the OPEN/CLOSE option from its title bar and then picking a displayed material symbol.

For more information about the Schematic window, see the Schematic Window section.

Last updated 02-apr-1998