IBL Terrain Legacy Shader

The terrain legacy shader offers an easy route into upgrading old assets to PBR shaders. However it should be noted that these shaders offer more or less direct conversions to the blending logic, the newer full IBL Terrain Shader is recommended for use wherever possible.

The shader uses exactly the same calculations as the old shaders to blend between maps. It replaces the Albedo alpha channels with roughness masks. And makes use of the new formats for mix spec maps and offers normal map blending functions. 

This page gives technical definitions.  For usage guide see: PBR - Using Terrain Shader

Shader Name



Please note UV_A, UV_B, UV_C or UV_D refers to as specified in the gTexture slot in 3ds Max. There is a full explanation of this here.

Blend Mode

Drop down options as follows:

  • Legacy_Layered: Upgrade Path for L2MultiGrass or "Multi layer grass / dirt" shader
  • Legacy_LayeredSat: Upgrade Path for L2MultiSatGrass or "Multi layer grass / dirt with Sat Map"
  • Legacy_Blended: Upgrade Path for variants of L2BumpSpecularMapT0lerpT1xT2VertexAlphaMaskT0T1 or "Bump Specular Map T1 lerp T2 mul T3 Vertex Alpha Mask T1T2"

Shadow Map

Enable the use of a Baked Shadow Map.

  • Baked Shadow Map: Choose which channel of the map to use, or disable the feature.
  • Shadow UV: Which UVW channel to use.

Translucency (Experimental)

  • Translucency: Enable or Disable Translucency on this material.
  • Invert Alb.R Mask: Use an inversion of the Albedo Red channel as a mask for the translucency. This will naturally make greener areas slightly more translucent than dry dirt.

General Configuration

  • Debug Blending: Enables blending with block colours to help debugging with blending patterns.
  • Receive Shadows: Enable or Disable receiving shadows.



This dialogue allows the scaling of the selected UV for any maps present.


This section allows the adjustment of final output of the material. 

  • AlbedoTint
  • ReflectionAt0Angle
  • Specular: 1.0 is recommend default for most materials. For natural materials this may need reducing to around 0.5 depending on the nature of your specular maps.
  • Roughness: Adjust overall Roughness, lower than 0.5 makes surfaces smoother. Above 0.5 makes surfaces rougher.
  • NormalShadowInflunce: Adjust the amount of influnce the normal map has on shadows cast onto this surface.


This allows you to set the intensity of the normal map on a per albedo basis.


Here you can configure what blend of Normal A and Normal B is used for each albedo map when using Layer modes.


Allows you to scale the strength of pattern map effect.

Legacy Blended

On the old Blended shader albedo alpha maps were used as a mask for the pattern effect. With the new shader we have a single per albedo constant only. The pattern map has two alternative channels, and this allows you to use a blend of the two on a per albedo basis.


Configure the Power (how broad or refined the effect is) and Strength of the Translucency effect as well as setup scalars on a per albedo map basis.

Debug Blending

Configure the colours used when debug blending is enabled.





Default File Types


albedoRoughAUV_ASRGB (Alpha linear)albaThe first albedo map with a roughness mask in the alpha channel.

Blended: UV_B

Layered: UV_B

Layered_Sat: UV_A

SRGB (Alpha linear)alba

The second albedo map with a roughness mask in the alpha channel.

This is blended in by Red Vertex Colour on Layer modes.

This is blended in by Vertex Alpha on the Blended mode.


Blended: UV_C

Layered: UV_D

LayeredSat: UV_C & UV_D

Linearpt or mua

With Blend Mode Legacy_Layered or Legacy_Blended

  • This is a linear BC5 map with two overlay patterns.
  • The first in the r channel and the second in the g channel.
  • The two are blended by blue vertex colour

With Blend Mode Legacy_Sat

  • This is a linear rgba BC7 map.
  • There is a multiplication map in rgb, and an overlay pattern in alpha.
  • There are seperate UV options for the RGB (UV_D) and Alpha (UV_C) channels.
  • The multiplication map is always used, and the pattern is blended in by blue vertex colour

Blended: UV_A

Layered & LayeredSat: Mix of UV_A and UV_C


This is a linear map with a mixmap or height map in the red channel, this is used to blend between albedo maps.

There is also also a specular mask in the green channel.

The map is sampled at the two sets of UV resolutions and blended with a 60% bias towards the higher scaling.


Layered: UV_C

LayeredSat: UV_B

SRGB (Alpha linear)alba

The third albedo map with a roughness mask in the alpha channel. This is blended in by Green Vertex Colour.

This is not used on the Blended mode.


NormalMapA and NormalMapB are blended based on the calculated overall value from the weights set in Normal_Blends

normalBUV_BLinearnmNot used in Legacy Blended mode.
shadowMapConfigureable, UV_D by default.Linearaos/splThis is added support to bake shadows into the terrain via a texture map.