In this chapter we'll talk about the Wrapper material functionality (MtlWrapper). The MtlWrapper can be used to specify additional surface properties per material.
Parameters
All parameters related to Wrapper material are located in VRayScene plugin.
- material_override – this is the actual surface material.
- mw_use - Use MtlWrapper
Additional Surface Properties
- mw_generate_gi – controls the GI generated by the material.
- mw_receive_gi – controls the GI received by the material.
- mw_generate_caustics – turn this off if the material should not generate caustics.
- mw_receive_caustics – turn this off if the material should not receive caustics.
Matte Properties
- mw_matte_surface – makes the material appear as a matte material, which shows the background, instead of the base material, when viewed directly. Note that the base material is still used for things like GI, caustics, reflections, etc.
- mw_alpha_contribution – determines the appearance of the object in the alpha channel of the rendered image. A value of 1.0 means the alpha channel will be derived from the transparency of the base material. A value of 0.0 means the object will not appear in the alpha channel at all and will show the alpha of the objects behind it. A value of -1.0 means that the transparency of the base material will cut out from the alpha of the objects behind. Matte objects are typically given an alpha contribution of -1.0. Note that this option is independent of the Matte surface option (i.e. a surface can have an alpha contribution of -1.0 without being a matte surface).
- mw_matte_for_secondary_rays – makes the material appear as a matte material, which shows the background instead of the base material when viewed through reflections and/or refractions.
- mw_shadows – turn this on to make shadows visible on the matte surface.
- mw_affect_alpha – turn this on to make shadows affect the alpha contribution of the matte surface. Areas in perfect shadow will produce white alpha, while completely unoccluded areas will produce black alpha. Note that GI shadows (from skylight) are also computed, however GI shadows on matte objects are not supported by the photon map and the light map GI engines, when used as primary engines. You can safely use those with matte surfaces as secondary engines.
- mw_shadow_tint_color – an optional tint for the shadows on the matte surface.
- mw_shadow_brightness – an optional brightness parameter for the shadows on the matte surface. A value of 0.0 will make the shadows completely invisible, while a value of 1.0 will show the full shadows.
- mw_reflection_amount – shows the reflections from the base material. This only works if the base material is directly a V-Ray Material | BRDFVRayMtl.
- mw_refraction_amount – shows the refractions from the base material. This only works if the base material is directly a V-Ray Material | BRDFVRayMtl.
- mw_gi_amount – determines the amount of GI shadows.
- mw_no_gi_on_other_mattes – this will cause the object to appear as a matte object in reflections, refractions, GI, etc. for other matte objects. Note that if this is on, refractions for the matte object might not be calculated (the object will appear as a matte object to itself and will not be able to "see" the refractions on the other side).
Misc
- mw_gi_surface_id - If two objects have different GI surface ids, the light cache samples of the two objects will not be blended
- mw_gi_quality_multiplier - A multiplier for GI quality
- mw_maya_background_shader_compatibility - Setting this to true will make the matte alpha opaque so that the alpha of objects behind the matte won't be seen.
- mw_trace_depth - The maximum reflection depth (-1 is controlled by the global options)
- mw_channels - Render channels the result of this BRDF will be written to
- mw_generate_render_elements - Setting this to false makes objects to not affect the render elements.
- mw_reflection_exclude - A list of plugins that will be excluded from reflections.
- mw_reflection_list_is_inclusive - Setting this to true will turn the reflection exclude list into inclusive (inverted).
- mw_refraction_exclude - A list of plugins that will be excluded from refractions.
- mw_refraction_list_is_inclusive - Setting this to true will turn the refraction exclude list into inclusive (inverted).
Example
The following picture is rendered using this scene. Take a look at the comments inside the included "wrapper.vrscene".
