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Material Properties

An introductory document on Material Properties in Unreal Engine.

Material Properties
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This document breaks down the properties available on a Material. These properties are displayed in the Details panel of the Material Editor when the Main Material Node is selected.

Material properties include:

All Material Properties
  • Physical Material
  • Material Properties
  • Physical Material Mask
  • Translucency and Translucency Self Shadowing
  • Usage Flags
  • Mobile
  • Forward Shading
  • Group Sorting
  • Post Process Material
  • Refraction
  • Lightmass Settings
  • Previewing
  • Import Settings

The properties listed above determine how what a Material can and cannot do, how it interacts with light and blends with the pixels behind it.. These properties are described below, presented in the order in which they appear in the Details panel.

Physical Material

Physical Material properties
Property Description
Phys Material The Physical Material associated with this Material. Physical Materials provide a definition of physics properties, such as how much energy is retained on collision (bounciness) and other physics-based aspects. A Physics Material has no influence over how a Material appears visually.
Phys Material Mask A physical Material mask used for this graphics Material. Used for sounds, effects, and more.

Material

Material Properties section
Property Description
Material Domain

Material Domain allows you to define how you will use the Material. Certain Material uses (such as decals) require additional instructions for the render engine to consider. Because of this, it is important to set the Material Domain accurately, particularly when the Material is intended for something other than a surface. Material Domain includes the following options:

Domain Description
Surface This setting defines the Material as something that will be used on an object's surface. Think metal, plastic, skin, or any physical surface. This is the default setting, and the one you will use most of the time.
Deferred Decal When making a Decal Material, you will use this setting.
Light Function Used when creating a Material for use with a Light Function.
Volume Used when describing the Material's attributes as a 3D volume.
Post Process Select this option when creating a Post Process Material.
User Interface Select this option when creating Materials for a UMG or Slate user interface.
Virtual Texture Used when making a Runtime Virtual Texture.
Blend Mode

Blend Modes describe how the output of the current Material will blend over what is already being drawn in the background. Put more technically, it allows you to control how the engine will combine this Material (Source color) with what is already in the frame buffer (Destination color) when rendered. The available blending modes are:

Mode Description
BLEND_Opaque Final color = Source color. This means that the Material will draw on top of the background. This blend mode is compatible with lighting.
BLEND_Masked Final color = Source color if OpacityMask > OpacityMaskClipValue, otherwise the pixel is discarded. This blend mode is compatible with lighting.
BLEND_Translucent Final color = Source color Opacity + Dest color (1 - Opacity). This blend mode is NOT compatible with dynamic lighting.
BLEND_Additive Final color = Source color + Dest color. This blend mode is NOT compatible with dynamic lighting.
BLEND_Modulate Final color = Source color x Dest color. This blend mode is NOT compatible with dynamic lighting, or fog, unless this is a decal material.
AlphaComposite Used for Materials with textures that have premultiplied alpha. That is, the color channel has already been multiplied by the alpha so when blending with the frame buffer, the GPU can skip the (SrcAlpha * SrcColor) arithmetic that is typically used with alpha blending. Can improve the visual appearance of additive blending.
AlphaHoldout Lets you "hold out" the alpha of a Material, punching a hole through Translucent objects directly behind it in view space.

For more information on these Blend Modes, read the Blend Modes documentation.
Shading Model

Shading Models determine how Material inputs (e.g. Emissive, Diffuse, Specular, Normal) are combined to make the final color.

Model Description
Unlit The Material is defined by the Emissive and Opacity inputs only. It does not respond to light.
Default Lit The default shading model. Perfect for most solid objects.
Subsurface Used for subsurface scattering Materials, such as wax and ice. Activates the Subsurface Color input.
Preintegrated Skin Used for Materials similar to human skin. Activates the Subsurface Color input.
Clear Coat Used for Materials that have a translucent coating on top like clear coat car paint or lacquer. Activates the Clear Coat and Clear Coat Roughness inputs.
Subsurface Profile Used for Materials similar to human skin. Requires the use of a Subsurface Profile in order to work correctly.
Two Sided Foliage Used for Materials that create natural looking foliage with accurate lighting and light transmission through surfaces, such as throug leaves on a tree.
Hair Used for Materials that create realistic looking hair that accurately lights the hair shafts and handles speular highlight.
Cloth Used for Materials that need to create realistic looking cloth and fuzz along its surface.
Eye Used for Materials that recreate the natural look of humanoid eyes.
Single Layer Water Eenables you to achieve the effect of a transparent water surface while using an Opaque Blend Mode. This reduces the cost and complexity of using Materials that require the Transparent Blend Mode.
Thin Translucent Used for Materials that create physically based glass, such as colored or tinted glass. It properly handles white specular from light sources and tinted background objects.
From Material Expression Used for handling multiple shading models in a single material.

For more information on these Shading Models, read the Shading Model documentation.
Two Sided When Two Sided is enabled, the normal is flipped on back faces, which means lighting is calculated for both the front faces and the back faces. This is commonly used on foliage to keep from having to double up the number of polygons. Two Sided does not work correctly with static lighting, since the mesh still uses only a single UV set for light mapping. As a result, two sided Materials with static lighting are shaded the same on both sides.
Use Material Attributes This checkbox causes the Material's primary node to be condensed down to a single input labeled "Material Attributes." This is useful when you need to blend multiple Materials using Layered Materials, or when defining multiple Material types using a Make Material Attributes expression node. See the Layered Materials[LINK NEEDED] documentation for more information.
Cast Ray Traced Shadows This checkbox enables this Material to cast ray traced shadows when Ray Tracing features are enabled in the Project Settings.
Subsurface Profile This allows you to change what Subsurface Profile is used in the Material.

Advanced Material Properties

Material Properties advanced
Property Description
Decal Response This defines how the Material reacts on DBuffer decals(Affects look, performance, and texture/sample usage). Non DBuffer Decals can be disabled on the primitive(e.g. static mesh)
Cast Dynamic Shadow as Masked Whether the Material should cast shadows as masked even though it has a translucent blend mode set.
Opacity Mask Clip Value This is the reference value which the OpacityMask input of masked Materials will clip against per-pixel. Any value higher than OpacityMaskClipValue will pass and the pixel will be drawn (opaque), any value lower will fail and the pixel will be discarded (transparent).
Dithered LOD Transition Whether meshes rendered with this material should support dithered LOD transitions.
Dither Opacity Mask When combined with Temporal Anti-Aliasing, this can provide a form of limited translucency which supports all lighting features.
Allow Negative Emissive Color Whether the Material should allow outputting negative emissive color values. This is only allowed on Unlit Materials.
Num Customized UVs This sets the number of Customized UV inputs to display. Unconnected customized UV inputs will pass through the vertex UVs.
Generate Spherical Particle Normals This produces surface normals that remain spherical as you rotate around a Particle System that uses this Material. This is useful for volumetric Particle Systems, since the sprites always rotate to face the camera. With this option, they will have a more spherical volume appearance.
Tangent Space Normal Tangent space normals are calculated from the surface of the object, with the Z-Axis (blue) always pointing directly away from the surface. World space normals use the world coordinate system to calculate pixel angle, ignoring the surface's original orientation. Tangent space calculations are slightly more costly in terms of performance, but are generally more convenient, as these are usually the types of normal maps you can create in 2D applications such as Photoshop. Visually, tangent-space normal maps tend to look primarily blue-ish, while world-space maps are more vividly rainbow-colored.
Emissive (Dynamic Area Light) If enabled, the Material's Emissive color is injected into the Light Propagation Volume.
Fully Rough Forces the material to be completely rough. This saves a number of material instructions and one sampler.
Normal Curvature to Roughness Reduces the roughness based on screen space normal changes.
Wire Frame Enables a wire frame view of the mesh the Material is applied to.
Shading Rate Select what shading rate to apply for platforms that have variable rate shading.
Is Sky Unlit and Opaque blend modes used in materials can be used as a Sky Material on a sky dome mesh. When enabled, these meshes will not recieve any contribution from the aerial perspective. Height and Volumetric Fog effects are still applied.
Asset User Data An array of user data stored with the asset.

Physical Material Mask

Physical Material Mask
Property Description
Physical Material Map An array of Physical Material Maps for use with this Material. The mask slots are used to apply sounds, effects, or some other type of Physical Material to a desired color channel.

Translucency

Translucency Properties
Property Description
Screen Space Reflections Enabling this supports screen space reflections (SSR) on translucent Materials.
Contact Shadows Enabling this supports contact shadows on translucent Materials.
Translucency Lighting Mode

This allows for control over the lighting mode used by Translucency within this Material. This is especially useful for Particle Systems that are making use of Translucency, such as self-shadowing smoke or steam.

Mode Description
Volumetric NonDirectional Lighting is calculated for a volume, without directionality. Use this on particle effects like smoke and dust. This is the cheapest lighting method, however, the material normal is not taken into account.
Volumetric Directional Lighting is calculated for a volume, with directionality so that the normal of the material is taken into account. Note that the default particle tangent space is facing the camera, so enable bGenerateSphericalParticleNormals to get a more useful tangent space.
Volumetric PerVertex NonDirectional Same as Volumetric NonDirectional, but lighting is only evaluated at vertices so the pixel shader cost is significantly less. Note that lighting still comes from a volume texture, so it is limited in range. Directional lights become unshadowed in the distance.
Volumetric PerVertex Directional Same as Volumetric Directional, but lighting is only evaluated at vertices so the pixel shader cost is significantly less. Note that lighting still comes from a volume texture, so it is limited in range. Directional lights become unshadowed in the distance.
Surface Translucency Volume Lighting is calculated for a surface. The light is accumulated in a volume so the result is blurry, limited distance but the per pixel cost is very low. Use this on translucent surfaces like glass and water. Only Diffuse lighting is supported.
Surface Forward Shading Lighting is calculated for a surface. Use this on translucent surfaces like glass and water. This is implemented with forward shading so Specular highlights from local lights are supported, however, many deferred-only features are not. This is the most expensive translucency lighting method as each light's contribution is computed per-pixel.
See Lit Translucency for more information on translucency usage in your Materials.
Directional Light Intensity Useful for artificially increasing the influence of the normal on the lighting result for translucency. A value lareger than 1 increases the influence of the normal, a value smaller than 1 makes the light more ambient.
Apply Fogging When enabled, translucent Materials are fogged.
Compute Fog Per Pixel When enabled, translucent Materials have fog computed for every pixel, which costs more but fixes artifacts due to low tessellation.
Output Velocity When enabled, translucent Materials will output motion vectors in the velocity pass.

Advanced Translucency Properties

Advanced translucency properties
Property Description
Render After DOF Indicates that the Material should be rendered in the Separate Translucency Pass (not affected by DOF, and requires "AllowSeparateTranslucency" to be set in the .ini file).
Responsive AA (anti-aliasing) Small moving objects, especially particles, can sometimes get obliterated by anti-aliasing. By setting this property to true, a different AA algorithm is used which provides more definition. Put another way, if you create a blizzard or similar particle system but cannot clearly see the snowflakes, this option should improve clarity. You should only use this option on small moving objects, because it creates aliasing artifacts on the background.
Mobile Separate Translucency Enable this option to render the Material in the Separate Translucency Pass. This means that the Material is not affected by DOF and also requires you to set bAllowSeparateTranslucency in the .INI files).
Disable Depth Test Allows the Material to disable depth tests, which is only meaningful with translucent blend modes. Disabling depth tests will make rendering significantly slower since no occluded pixels can get Z-culled.
Write Only Alpha Whether the translucency pass should write its alpha, and only the alpha, into the framebuffer.
Allow Custom Depth Writes Allows you to use a translucent Material with custom depth writing by compiling additional shaders.

Translucency Self Shadowing

Translucency self-shadowing properties

Translucent self shadowing is a nice way to create a volumetrically lit translucent object, such as a pillar of smoke or steam. The self shadowing is broken into two primary parts: Self Shadow Density and Second Self Shadow Density. The two parts exist to allow for variations. You can define the density of each independently and use the difference between the two to get interesting patterns throughout the self shadow.

Property Description
Shadow Density Scale Sets the density of the shadow cast onto other surfaces by this translucent Material. This acts a bit like a master scale for shadowing; if set to 0, there is no shadowing whatsoever. As you increase the value to 1 and beyond, both the cast shadow and the self shadow will get darker.
Self Shadow Density Scale Sets the density of the shadow this Material casts on itself. Consider shadows within a pillar of smoke.
Second Density Scale This is a second self shadow density that can be set for variation. An internal gradient is created between this value and the Translucent Self Shadow Density Scale.
Second Opacity This sets the opacity value for secondary self shadowing., serving as a way to scale the gradient effect between self shadow and second self shadow.
Backscattering Exponent This controls the backscattering that is used when employing the Subsurface shading model along with Translucency. Larger values give a smaller, brighter backscattering highlight. This value is only used within volumetric translucent shadows formed from a directional light.
Multiple Scattering Extinction This gives a colored extinction value for objects that have a volumetric translucent shadow, such as smoke or steam. This amounts to a tinited or colored shadow.
Start Offset This is a world-space offset for the self shadow created within a translucent volume. The higher the number, the farther the shadow moves away from the lighting source.

Usage

Usage flags

The Usage flags tell the Engine what sort of surface you intend to apply the Material on. These settings allow the Engine to compile special versions for each application. These are only valid when using the Surface Material Domain setting.

In the editor, these flags are set automatically for any objects that already exist within your maps. For instance, if you have a Particle System that uses your Material placed somewhere in a level, when you load that map in the editor, it will automatically set the Used with Particle System flag. You must save the Material asset to allow the game to use the Material on that specific mesh.

If you do not have the appropriate usage flag set, the default world grid material will be used in-game instead. This will have an appropriate message in the log of the game client.
Property Description
Used with Skeletal Mesh Set this if the Material will be placed on a Skeletal Mesh.
Used with Editor Compositing Set if the Material will be used with the Editor UI.
Used with Particle Sprites Used if this Material will be placed on a Particle System.
Used with Beam Trails Set if the Material will be used with Beam Trails.
Used with Mesh Particles Indicates that the Material and its instances can be used with mesh particles. This will result in the shaders required to support mesh particles being compiled which will increase shader compile time and memory usage.
Used with Niagara Sprites Set if the material will be used with Niagara Sprites.
Used with Niagara Ribbons Set if the material will be used with Niagara Ribbons.
Used with Niagara Mesh Particles Set if the material will be used with Niagara Mesh Particles.
Used with Geometry Cache Set if the material will be used with Geometry Cache.
Used with Morph Targets Set if this Material will be applied to a Skeletal Mesh that utilizes a Morph Target.
Used with Spline Meshes Set if the Material will be applied to Landscape Spline meshes.
Used with Instanced Static Meshes Set if the Material is intended to be applied to Instanced Static Meshes.
Used with Geometry Collections Set if the material is intended to be used with geometry collections.
Used with Clothing This should be set if the Material will be applied to Apex physically simulated clothing.
Used with Water Used with materials that are intended to be used with Water mesh surfaces.
Used with Hair Strands Used with materials that are intended to be used with hair grooms.
Used with Lidar Point Cloud Used with materials that are intended to be used with Lidar Point Clouds.
Used with Landscape Set if the Material will be used on a Landscape surface.
Used with UI This indicates that this Material and any Material Instances can be used with Slate UI and UMG.
Automatically Set Usage in Editor Whether to automatically set usage flags based on what the Material is applied to in the Editor. The default option for this is enabled.

Mobile

Mobile Material properties
Property Description
Use Full Precision Forces this Material to use full (highp) precision in the pixel shader. It is slower than the default (mediump) but provides a workaround for precision-related rendering errors. This setting has no effect on older mobile devices that do not support high precision.
Use Lightmap Directionality This will use lightmap directionality and per pixel normal's. If disabled, lighting from lightmaps is flat but cheaper.

Forward Shading

Forward shading properties
Property Description
Preintegrated For Simple IBL Forward (including mobile) renderer uses preintegrated GF LUT for simple IBL, but will use one more sampler.
High Quality Reflections The forward renderer enables multiple parallax-corrected reflection captures that blend together. The Mobile forward renderer blends between the nearest three reflection captures, but reduces the number of samplers available to the Material as two more samplers are used for reflection cubemaps.
Planar Reflections Enables planar reflection when using the forward renderer or on mobile. Enabling this setting reduces the number of samplers available to the Material as one additional sampler is used for planar reflection.

Post Process Material

Post-process Material setttings
Property Description
Blendable Location If this Material is used as a Post Process Material, this property allows you to control whether the Material is calculated before or after Tonemapping. This is important if your Material is used to modify the color of the Post Process.
Output Alpha If enabled, the blendable will output alpha.
Blendable Priority If multiple nodes with the same type are inserted at the same point, this defines the order and whether or not they get combined. Only used if Material domain is set to PostProcess.
Is Blendable Allows blendability to be turned off. It is only used if the Material Domain is set to Post Process.
Advanced Properties  
Enable Stencil Test Selectively executes post process Material only for pixels that pass the stencil test against the Custom Depth/Stencil buffer. Pixels that fail the stencil test are filled with the previous post process Material output or scene color.
Stencil Compare Use the dropdown to compare the stencil test.
Stencil Ref Value Set a stencil reference value.

Refraction

Refraction properties
Property Description
Refraction Mode

This controls the type of refraction that will be employed by your Material.

Mode Description
Index Of Refraction Refraction is computed based on the camera vector entering a medium whose index of refraction is defined by the Refraction material input. The new medium's surface is defined by the Material's normal. With this mode, a flat plane seen from the side will have a constant refraction offset. This is a physical model of refraction but causes reading outside the scene color texture. so is a poor fit for large refractive surfaces, like water.
Pixel Normal Offset The refraction offset into scene color is computed based on the difference between the per-pixel normal and the per-vertex nromal. With this mode, a material whose normal is the default (0,0,1) will never cause any refraction. This mode is only valid with tangent space normals. The refraction material input scales the offset, although a value of 1.0 maps to no refraction, and a value of 2 mapts to a scale of 1.0 on the offset. This is a non-physical model of refraction, but is useful on large refractive surfaces like water, since offsets have to stay small to avoid reading outside scene color.
Refraction Depth Bias This property offsets the depth of the refraction test. This is useful when refraction values are causing unwanted nearby objects (typically in front of the translucent object) to render into the Material surface. Higher values will offset distortion to separate refractions. However, this causes a visible break between the surface and the refracted objects. This property is not enabled unless you have connected some expression node into the Refraction input.

Lightmass

Lightmass settings properties
Property Description
Diffuse Boost A multiplier for the amount of influence the diffuse component of the Material has on static lighting.
Export Resolution Scale A multiplier for the resolution at which this Material's attributes are exported. This should be increased when details are needed.
Cast Shadow as Masked If true, lit translucent objects will cast shadows as if they were using Masked lighting mode. This can help get sharper shadows on translucent objects.

Previewing

Previewing properties
Property Description
Preview Mesh Sets a Static Mesh used to preview the Material in the Preview viewport.

Import Settings

Import settings properties
Property Description
Asset Import Data A selection of import data types and options relevant to the selection for use with this Material. For example, selecting Fbx Texture Import Data provides its own set of properties that affect this import type.

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