Procedural Textures

This section introduces a second form of material definition, that of procedural textures.

Material definitions

A common problem that occurs with standard materials is that of inconsistencies when the material “wraps around” a solid. Take, for example, a wood material, applied to a sphere, slab and cylinder:

• The sphere looks like a beach ball, with the woodgrains “bunched up” unnaturally at the “poles.”

• Grains displayed on the slab and cylinder don't align at the edges where surfaces meet.

While rotating the pattern 90° may reduce the problems (particularly with the sphere), making them less noticeable, that is a work-around and not a solution. These mismatches are inherent with the method used to apply the material. It is similar to applying a laminate or wallpaper to a surface. That is, the same pattern (material definition) is applied separately to each surface of each solid. Additionally, on a large area, tiling occurs where the image used for the material is repeated.

These problems can be overcome with procedural textures, which produce natural looking materials.

Advantages of procedural textures

Each procedural texture is a self-contained MDL application that computes and applies the material definition to the selected solid or surface. As well as the standard user defined parameters that appear in the Material Editor dialog box, and the Mapping paramters in the Map Editor, further parameters are available when you open the Map Editor dialog box for the pattern map, or bump map. These additional parameters are specific to each procedural texture.

Map Editor with pattern map (left) and procedural texture (right).

Thus, procedural textures have major advantages over standard material definitions:

• They look more natural because there are no seams caused by texture wrapping.

• They have virtually infinite resolution.

• They have editable settings allowing greater control over the material definition.

• A single procedural texture can be used to create a range of similar materials.

3D procedural textures

When applied to a solid or surface, a 3D procedural texture produces a different pattern for each axis. The effect is that the solid or surface appears to have been carved out of a single block of the material.

When a 3D procedural texture is used, there is no need to specify different materials for the top and sides of a model, as may be required with standard pattern maps. Variations of the material can be created by changing the Size X, Y, and Z values for the material in the Map Editor dialog box. This lets you change the appearance of the material along any of the axes.

Consider the previous sample model with the sample 3D procedural texture “wood” applied. As shown in the following image, with a procedural texture, the sphere looks as though it was cut from a single material. On the slab, different patterns are applied to each face. Furthermore, the grains on each face of the slab and the grains on the cylinder render correctly. They run in the correct direction relative to each other and meet correctly at the edges. These differences in the top and sides were generated from the one 3D procedural texture.

2D procedural textures

Like their 3D counterparts, you can change the appearance of 2D procedural textures using the Size X, and Y values in the Map Editor dialog box. Each 2D procedural texture has its own specific settings as well, to control various aspects of its appearance. For example, you can change the thickness of the mortar in the brick texture, as well as the color of the bricks or mortar.

While 2D procedural textures work similarly to normal pattern maps, they are calculated for each surface. This may result in them not matching at edges, but on the other hand, there is none of the tiling that can occur with a normal pattern map (when a pattern is repeated).

2D procedural textures “brick” and “boards” applied to surfaces.

Sample procedural textures

The material palette, “proctext.pal,” which is installed in the "Workspace\system\material" directory, contains each sample procedural texture that is installed in MicroStation's "mdlsys\textures" directory.

Sample of 3D procedural textures

Wood	Wood (another one)	Marble	Marble (another one)
Black/white noise	Color noise	Turbulence
Checker (3D)	RGB color cubes	Waves

Sample of 2D procedural textures

Boards	Brick	Checker (2D)
Sand	Turf

Special online help is supplied for each sample procedural texture. This includes information on the procedural texture's specific parameters and how they affect its appearance.