Enable diffuse reflections.

The proportion of incoming light reflected back as the diffuse component, from 0 (no diffuse reflection) to 1 (all incoming light is reflected). Non-attenuated lights such as point lights and spot lights may produce brighter pixel values than this value.

(Old shaders such as the VEX Plastic shader implicitly have a reflectivity of 0.5 when the shader’s diffuse coefficient is set to 1.)

A floating point value used to control the size or spread of the diffuse component. Higher values make the surface look less glossy with flatter color.

When Fresnel Blending is on, controls the minimum amount of reflection that will not be blended with the Fresnel factor. Diffuse components are blended with the transmissive Fresnel component.

Fresnel blending of the diffuse component only makes sense when one or both specular reflection layers are on. If there is no specular reflection, you should turn off Fresnel Blending.

Use the base color below to color the surface. If Use point colors and/or Use color map are also on, the base color will be multiplied with them.

The base color to use for surface shading when Use base color is on.

Use values stored in the object geometry’s Cd point attributes to color the surface. If Use base color and/or Use color map are also on, the point color will be multiplied with them.

Use color attributes on packed primitives. This is multiplied against the existing diffuse color values.

Use a texture map to color the surface. If Use base color and/or Use point colors are also on, the texture color will be multiplied with them.

The texture map to use for surface shading when Use color map is on.

The blending factor between the base color and the color map, from 0 (base color only) to 1 (fully blend the color map with the base color).

Determines what the texture looks like when the texture coordinates are outside of the [0,1] range.

See texture for more information.

Type of anti-aliasing filter used.

See texture for more information.

Filter Width is the number of pixels, in both u and v directions, to use in filtering.

See texture for more information.

Turns on simulation of light refracting through the object.

Light sources (including environment lights) will appear in refractions.

Show refractions of objects. You should normally leave this option on (otherwise no refractions will appear) unless you are simulating a single sheet of reflective material, and you still want light to filter through the object.

The mathematical model used to simulate glossy refractions. For each viewing angle and surface normal, the model defines from which directions and at what intensity light is refracted. This is what shapes highlights and refractions in general.

The overall glossiness, and with it the size of highlights, is controlled by Refraction Roughness.

The chosen model has no effect when Refraction Roughness is 0, since this causes light to be refracted from a single direction at full intensity, making the model irrelevant.

Treat the surface of the shaded object as a thin refractive film rather than the boundary between the outside of the object and a solid interior. Turn this on to simulate hollow and/or thin refractive objects such as bubbles or windows. The node still uses the refractive index to calculate the proportion of reflection and refraction for fresnel blending, but the transmitted ray will not change direction.

The shaded surface’s place in an order of precedence for overlapping transparent materials. A value of 0 means the surface priority should be ignored. Surfaces with lower numbers (higher priority) “override” surfaces with higher numbers (lower priority). Mantra will only calculate the shaders for the highest priority object in a given area, creating the effect of higher priority objects overriding and removing lower priority objects in the same overlapping space.

In this render, the red sphere and the blue box have the same surface priority. This causes problems with refraction and absorption, because it’s not clear to Mantra which surface is inside or outside.

In this example, the red sphere has a higher priority than the blue box (lower numbers mena higher priority) so it “carves out” its volume from the box (Mantra simply ignores whichever parts of the box have overlapped the sphere). The absorption and refraction is now correct for the red sphere being embedded in the blue box. This setup would work well for something like ice cubes floating in water.

In this example, the surface priority values are switched so the blue box has higher priority. This has the effect of removing any parts of the red sphere which overlapped the blue box. This setup would work for something like water droplets resting on the surface of a glass.

This parameter only takes effect when Enable Absorption and Nested Dielectrics is turned on in the Mantra render node.

The proportion of light refracted by the surface, from 0 (no light refracted) to 1 (all incoming light is refracted).

When Fresnel Blending is on, controls the proportion of refraction that will not be blended with the Fresnel factor. Increasing this parameter will cause a minimum amount of refraction to appear even for rays that graze the surface (and so would normally not refract).

A tint for the refracted light (technically, the refraction amount for different color components). For example, setting the refraction color to 1, 0, 0 will cause the surface to refract only red light.

Roughness is a measure of how bumpy a surface is at the microscopic level. The most obvious effect is that refractions become glossier as roughness increases.

At a value of 0, the surface is perfectly smooth and produces perfect refractions like glass. A value of 1 simulates a very rough surface, which results in very blurry refractions, like milky glass.

The visual change when transitioning from 0 to 1 should be close to linear.

The direction and amount of anisotropy in the refraction. Values less than 0 will sharpen the refraction in the U direction while values larger than 0 will sharpen the refraction in the V direction. When the Refraction Anisotropy is -1 or 1, refractions will have a width of 0 in the other direction.

Spreads and colors refraction rays to simulate the effect of a spectrum of wavelengths within the refracted light. The larger this value, the larger the spectral separation.

When this parameter is set to a non-zero value, refracted rays are tagged with a single wavelength in the visible spectrum. Each of these wavelengths modify the underlying index of refraction (IOR) causing the rays to separate as they travel through the refractive material.

Tint rays with this color as they pass through an object. The amount of tinting depends on the distance a light ray travels within the object. You can scale the tinting using At distance.

A ray must travel this distance within the object before it is completely colored by the Transmission color. Shorter distances give less tinting, longer distances give a darker and more saturated version of the Transmission Color.

Simulate subsurface scattering of light through the object.

The overall proportion of light that is scattered, from 0 (no scattering) to 1 (all light is scattered). Higher subsurface albedo values will produce more multiple scattering and a greater scattering distance.

The minimum scattering intensity.

Controls the nature of the scattering. Positive values give forward scattering, 0 gives isotropic scattering, and negative values give backscattering. Range is -1 (full backscattering) to 1 (full forward scattering).

The value depends on the type of material you are trying to model. For example, skin is highly forward scattering, while marble is backscattering.

Enable/disable contribution from light that scatters exactly once in the surface. Certain types of surfaces (such as skin) gain little contribution from single scattering and so disabling this option will reduce computation time with little impact on accuracy.

A scaling factor for the contribution of single scattering to the surface color, from 0 (no contribution) to 1 (full contribution).

The number of samples for single scattering. Increase this option to decrease noise at the expense of slower shading.

Enable contribution from light that scatters more than once in the surface. For low albedo materials (low Subsurface Albedo), multiple scattering contributes little to the image and can be disabled to reduce computation time.

Controls the way in which multiple scattering is computed. Normally you should use the Local And Global mode if you are planning to use a point cloud, and Ray Tracing to compute multiple scattering without a point cloud. Using a point cloud can produce smoother and faster results, but it requires precomputation of a point cloud and computation of irradiance for each point in the cloud (once per render).

Controls how the shader generates a point cloud. The simplest option is to select Generate At Render Time. This will create a new point cloud for every render. To reduce computation time, you can first use Write To File mode and then re-use the point cloud using Read From File mode on subsequent renders. This is also the recommended approach when rendering animations because the shader will smoothly interpolate the point cloud across frames. The exception to this is when the model’s topology changes (two joined polygons are separated, for example). In this case, a new point cloud must be generated. Note that in Write To File mode, the file will be overwritten if it already exists. Cancelling a render before it completes in Write To File mode may result in an unusable point cloud file.

See managing point clouds for more information.

Controls the file the point cloud is written to/read from when Point Cloud Mode is Write To File or Read From File. The point cloud is based on surface UVs, so it is not necessary to write a new point cloud file for each frame unless the topology of the model is changes.

A scaling factor for the contribution of multiple scattering to the surface color, from 0 (no contribution) to 1 (full contribution).

Controls the number of samples in the point cloud. Low values give fast renders but a sharper, less accurate look. High values give slower renders but a blurrier, more accurate look.

The dominant color in lit areas of the surface.

Use a texture map to tint the rays entering the surface.

The texture map to use when Use subsurface map is on.

The blending factor between the original color of the rays and the subsurface map, from 0 (original color only) to 1 (fully blend the subsurface map with the ray color).

Determines what the texture looks like when the texture coordinates are outside of the [0,1] range.

See texture for more information.

Type of anti-aliasing filter used.

See texture for more information.

Filter Width is the number of pixels, in both u and v directions, to use in filtering.

See texture for more information.

How quickly the light intensity decreases as it scatters. Higher values make the lighting level decrease faster. Available when Parameter mode is Artist.

Use a texture map for the attenuation color.

The texture map to use when Use Map is on.

The blending factor between the Attenuation color and the Attenuation map, from 0 (attenuation color only) to 1 (fully blend the attenuation map with the attenuation color).

Determines what the texture looks like when the texture coordinates are outside of the [0,1] range.

See texture for more information.

Type of anti-aliasing filter used.

See texture for more information.

Filter Width is the number of pixels, in both u and v directions, to use in filtering.

See texture for more information.

Add a constant amount of diffuse light emitted from the surface. For example, with emission on, the object would be visible in the render even if none of the light objects were shining on it. This may be useful in some circumstances, but normally you should simply use an Area Light to add light to the scene more efficiently and controllably, especially if you need to add a lot of light.

The light emitted by this object will brighten the surfaces of other objects. When this option is off, the emitted light will be visible in the camera, but will not fall on other objects in the scene.

The amount of emission.

The color of the emitted light.

Use a texture map for the emission color.

The texture map to use when Use Map is on.

The amount of influence the map has on the final color.

Scales the value of the Opacity parameter. This is useful as a single number to manipulate rather than having to change all three components of the Opacity parameter together.

The opacity of the red, green, and blue channels of the shaded surface color.

Use a texture map to control the opacity of the shaded surface color.

The texture to use for surface color opacity when Use Map is on.

The blending factor between the Opacity color and the Opacity map, from 0 (opacity color only) to 1 (fully blend the opacity map with the opacity color).

Determines what the texture looks like when the texture coordinates are outside of the [0,1] range.

See texture for more information.

Type of anti-aliasing filter used.

See texture for more information.

Filter Width is the number of pixels, in both u and v directions, to use in filtering.

See texture for more information.

Blend between different opacities for parts of the surface that are perpendicular (head-on) to the camera and parts that are parallel (edge-on).

The opacity to use for rays that are parallel to the surface normal, when Enable opacity falloff is on.

The opacity to use for rays that are perpendicular to the surface normal (rays that graze the surface), when Enable opacity falloff is on.

Controls the blending point between parallel and perpendicular opacity. Values larger than 1 give more parallel opacity, values smaller than 1 give more perpendicular opacity.

Transmissive objects produce semi-transparent shadows that attempt to approximate the amount of light that would be transmitted if real caustics were rendered. If you're rendering real caustics using an Indirect Light, turn this parameter off.

The minimum shadow intensity to use for fake caustics. Increase this to darken the lightest part of the shadow.

The maximum shadow intensity to use for fake caustics. Decrease this to lighten the darkest part of the shadow.

Automatically flip normals if necessary so planal surfaces are diffuse shaded the same way regardless of normal direction. This setting does not apply to refractions and Fresnel reflections since they rely on the normal direction to define inside and outside for Fresnel blending.

Ensures that the surface reflects no more light than it receives. This is important in physically based rendering and raytracing to ensure the illumination in the scene does not increase as the number of raytracing bounces increases. For example, a surface that reflects twice as much light as it receives (by turning off Conserve Energy and setting the Specular Intensity to 2) would produce a unnaturally bright render as you increase the Reflect Limit.

This setting conserves energy by scaling the BSDF by the inverse of its reflectivity when the node detects the reflectivity is greather than 1. This reduces all components of the surface model by the same factor, linearly darkening of the surface.

You can calculate the total reflectivity of a surface (assuming Fresnel Blending is off) by summing the Diffuse Intensity, Specular Intensity (for each layer) and Refraction Intensity. For predictable results, you should try to conserve energy manually by limiting the intensity or reflectivity parameters.

The interior index of refraction for use in physical Fresnel computations. Water has an index of refraction around 1.33.

The exterior index of refraction for use in physical Fresnel computations. Air has an index of refraction near 1.

Turns on Fresnel blending, where the reflection and/or refraction amount varies based on the viewing angle to the surface. This allows you to simulate materials such as glass and water. You can control the proportion of Fresnel blending for each component through the “minimum” parameters on the different tabs (for example, Diffuse Minimum on the Diffuse tab).

Diffuse and Refract components use the transmissive component for Fresnel blending, while Reflect components use the reflective component.

Choose whether to output normals that have been modified by the shader, or output a difference between a high res and low res geometry.

The coordinate system in which to output the normals. Use tangent space for deforming objects, so the normals stay relative to the moving surface.

Some target applications might require a certain space for tangent maps. Commonly, game engines and other real time systems use tangent space maps.

Map the normal data into specific range. Either -1 to 1 or 0 to 1.