Wavefront .obj File - Material Template Library - Introduction - Basic Materials

Basic Materials

A single .mtl file may define multiple materials. Materials are defined one after another in the file, each starting with the newmtl command:

# define a material named 'Colored' newmtl Colored

The ambient color of the material is declared using Ka. Color definitions are in RGB where each channel's value is between 0 and 1.

Ka 1.000 1.000 1.000 # white

Similarly, the diffuse color is declared using Kd.

Kd 1.000 1.000 1.000 # white

The specular color is declared using Ks, and weighted using the specular coefficient Ns.

Ks 0.000 0.000 0.000 # black (off) Ns 10.000 # ranges between 0 and 1000

Materials can be transparent. This is referred to as being dissolved. Unlike real transparency, the result does not depend upon the thickness of the object.

d 0.9 # some implementations use 'd' Tr 0.9 # others use 'Tr'

Multiple illumination models are available, per material. These are enumerated as follows:

0. Color on and Ambient off 1. Color on and Ambient on 2. Highlight on 3. Reflection on and Ray trace on 4. Transparency: Glass on, Reflection: Ray trace on 5. Reflection: Fresnel on and Ray trace on 6. Transparency: Refraction on, Reflection: Fresnel off and Ray trace on 7. Transparency: Refraction on, Reflection: Fresnel on and Ray trace on 8. Reflection on and Ray trace off 9. Transparency: Glass on, Reflection: Ray trace off 10. Casts shadows onto invisible surfaces illum 2