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This page provides information on the Mtl2Sided material node.

Overview

V-Ray Mtl2Sided material node is a utility provided with the V-Ray renderer. The material allows seeing the light on the backside of objects.

Use this material to simulate thin translucent surfaces like paper, cloth curtains, tree leaves, etc.

V-Ray for Houdini > V-Ray Two Sided > 2_Translucency_grey.png

Node

The Mtl2Sided node provides inputs for controlling various material properties. Some correspond to parameters in the section below.

front – Specifies the material which is going to be used for front-side faces as defined by the object normals.

back – Specifies the material V-Ray uses for back-side faces as defined by the object normals.

V-Ray for Houdini > V-Ray Two Sided > Hou19_VRay6_TwoSided_node.png

Parameters

Translucency – Determines which side (front or back) relative to the camera is more visible in the rendering process. By default this value is 0.5, which means that both the side facing the camera, and the one facing away from it, are visible to the same degree. When this parameter is closer to 0.0, more of the material facing the camera is going to be seen. When it is closer to 1.0, more of the back material is seen. See the Translucency example below.

Multiply by Front Diffuse – When enabled, multiplies the back side color by the cached diffuse color of the front BRDF. See the Multiply by Front Diffuse example below.

Force Single-sided Sub-materials – When enabled (the default), the sub-materials render as one-sided materials. Turning this option off is not recommended.

V-Ray for Houdini > V-Ray Two Sided > Hou19_VRay6_VRay2Sided_parameters.png

Example: Translucency

This example shows the effect of the Translucency parameter. We use a V-Ray Two Sided material with two different V-Ray Materials for the front and back sides. Note that the Multiply by Front Diffuse option is enabled.

V-Ray for Houdini > V-Ray Two Sided > 2_Translucency _black.png

Translucency is set to black.

No light is passing through and the back material is not visible.

V-Ray for Houdini > V-Ray Two Sided > 2_Translucency_grey.png

Translucency is set to grey.

This allows light from the back to pass through and makes both materials visible.

V-Ray for Houdini > V-Ray Two Sided > 2_Translucency_white.png

Translucency is set to white.

This allows all the light to pass through. Only the back material is visible in the render.

Example: Multiply by Front Diffuse

This example shows the effect of the Multiply by Front Diffuse parameter.

V-Ray for Houdini > V-Ray Two Sided > 1_Multiply_off.png

V-Ray for Houdini > V-Ray Two Sided > 1_Multiply_on.png

Notes

This material gives best results when assigned to singleside objects (non-shelled) objects like planes, extruded splines, etc. Otherwise, it can lead to extremely longer render times.