UE5 - Materials

PBR

• Base Color
  • Real world materials are not darker than 20 srgb or brighter than 240 srgb
  • Rough surfaces have a higher minimun, around 50 srgb
  • Out of range values will not light correctly, so staying in range is critical
  • On a non-metallic material this controls the diffuse
    • On a metallic material this controls the specular
    • On a metallic material the diffuse is black
• Specular
  • A multiplier for the direct and indirect specular lighting
  • Defining the reflectivity when looking straight at the surface
  • Non-metal surfaces reflects about 4% of the light
  • Specular value:
    • 0.5 represents 4% reflection
    • 1.0 represents 8% reflection (to high for most materials)
  • At glancing angles all surfaces are 100 % reflective
    • The fresnell term is built into the engine
  • Specular maps should mostly be at 0.5
  • Only use lower values to mask areas that should not be reflective like crevices
    • A crevice map multiplied with 0.5 makes a good specular map.
• Roughness
  • Represents the roughness of the surface at a microscopic scale.
  • White is rough and black is smooth
  • Controls the focus of reflections
    • Smooth = tight, sharp reflections
    • Rough = blurry, diffuse reflections
  • No technical constraints - completely artistic choice
    • A roughness map can be used to define the “character” of the surface and show its history
• Metallic
  • Switches the shader to metallic mode
  • When the metallic is set to 1 (a metallic material)
    • Now the base color controls the specular of the material
    • Now the specular range is up to 100%
    • Most metals are between 60-100% reflective
    • Be sure to use real-world measurements for metal “base color”
      • Metals have colored reflections
      • The values should be around 180 srgb or brighter
      • The base color controls the specular
    • The specular parameter is ignored (since it is controlled by the base color)
    • The diffuse is always black
  • Values of either 0 or 1 should be used.
    • Values in between should be avoided since that will produce a weird mix of non-metal / metal behaviour
    • A few pixles of “inbetween values” where a map transitions from 0 to 1 are ok, but generally the map should be 0 or 1
• Ambient Occlusion
  • Only used if we use a baked gloabl illumination solution.

Landscape

• Material Attributes
  • on the result node of the material click Details > Material > Use material Attributes : On

Nodes

Math / Misc

• Mask - [math] componentMask
  • Selects a specific subset of channels (R, G, B, and/or A)
• Split Components - [Misc] splitComponents
  • Can split out components of a vec3. (Can not output alpha vec4)
• Append - [Math] appendVector
  • Construct a vector with more channels than the original. You can appen to floats to create a vec2 or one float and a vec2 to cfreate a vec3.
• AppenMany - [Misc] appendMany
  • Allows you to append up to 4 scalars in one function
• Swizzle - [Misc] swizzle
  • Can rearrange the components of a vector

Textures

• Dropping one resolution step reduces memory 4 times.
• Using 4k textures is very expensive
• Uncompressed textures need to be at a low resolution, otherwise they will require alot of memory.
• Using a alpha channel doubles memory usage, since the alpha channel are stored at a higher quality
  • Therefore if you pack channels you should pack the channel that needs the best quality in the alpha.

Compression

• Optimization
  • Reduce in game texture size
    • texture editor > details tab > compression > advanced
    • Set the maximum texture size to the size you want
    • Note that a value of 0 will use the original size
  • Compress without Alpha
    • If your texture has an alpha channel but you do not need it you can make the editor skip the alpha
    • This will reduce the size by half
    • texture editor > details tab > compression
    • enable Compress without alpha

Samples

Material Functions