Material Editor > Type button > Material/Map Browser > Glass (physics_phen)
Note: The Glass material appears in the Browser only if the mental ray renderer is the currently active renderer.
The Glass material simulates both the surface properties and the light-transmitting (photon) properties of glass. It is a mental ray phenomenon (a scripted shader tree) that is equivalent to a mental ray material with a Dielectric Material shader assigned to both its Surface and Photon components, with the parameter settings identical for both. A dielectric material, such as glass, is a material whose surface transmits most light that strikes it at angles close to perpendicular (90 degrees), but reflects most light that strikes at glancing angles (close to zero degrees).
Note: This material does not use a shadow shader, so shadows will always be opaque unless you generate caustics.
Two controls, Outside Light Persistence and Index Of Refraction (Out), are for situations where you are modeling two adjacent refractive materials. Consider a drink in a martini glass. The glass has an index of refraction (IOR) of 1.5, while the alcohol in the glass has an IOR of about 1.3. To create a physically accurate model of this situation, use three glass materials: one for the glass itself, one for the alcohol, and a third material for the surfaces where they touch each other. For this third material, set the “inside” IOR to 1.3, and the outside IOR to 1.5.
Light Persistence—In conjunction with the Persistence Distance, controls the percentage of light that the volume transmits. For example, if the color is set to R=G=B=0.5 and the Persistence Distance is set to 2.0, then objects with a thickness of 2.0 units will appear 50 per cent transparent. Default=white (R=G=B=1.0).
Because transparency depends on the thickness of the object, objects with varying thickness show different transparency depending on the angle from which they are viewed.
Index Of Refraction—Specifies the Index Of Refraction (IOR). In the physical world, the IOR results from the relative speeds of light through the transparent material and the medium the eye or the camera is in. Typically this is related to the object's density. The higher the IOR, the denser the object. Default=1.5.
See Extended Parameters Rollout (Standard Material) for a list of IOR values for commonly encountered materials.
Outside Light Persistence—In conjunction with the Persistence Distance, controls the percentage of light transmitted on the other side of a surface. When set to the default of black, this control has no effect. See the section “Adjacent Refractive Materials,” above. Default=black (R=G=B=0.0).
Index Of Refraction (out)—Sets the IOR on the other side of a surface. When set to the default of zero, this control has no effect. See the section “Adjacent Refractive Materials,” above. Default=0.0.
Persistence Distance—In conjunction with the Light Persistence color, controls the percentage of light that the volume transmits. It is the distance at which light transmission is reduced to the percentage specified by the Light Persistence RGB values. Default=1.0.
If you specify an Outside Light Persistence color, that setting also uses the Persistence Distance.
Ignore Normals—When on, the renderer does not use normals to decide whether a light ray is entering or leaving the object. Normally, the material uses normals to decide whether a ray is entering or leaving an object. (It is entering if the normal points toward the ray, leaving if the normal points away from the ray.) This can present a problem for rendering objects whose normals are not unified. hen Ignore Normals is on, the material decides whether a ray is entering or leaving the object by counting the number of times the ray has intersected the object. Default=off.
Opaque Alpha—When on, refracted rays that touch the environment don't generate a transparent alpha value. (This is how 3ds Max usually treats the environment.) When off, refracted rays that touch the environment render a transparent alpha value, which can help if you plan to use the rendering as part of a composite. Default=off.
Phong Coefficient—When greater than zero, generates Phong highlights on the material. The highlights appear in the sample slot. In general this value must be greater than 10 for highlights to be apparent. Default=0.0.