Normal maps

Intermediate Artist Programmer

Normal maps are textures that add the appearance of surface detail, such as cracks and bumps, without changing the actual geometry of a model. This saves lots of processing power.

No normal map With a normal map
media/material-attributes-15.png media/material-attributes-16.png

Normal map example

(Image courtesy of Paolo Cignoni, shared under Attribution-ShareAlike 1.0 Generic (CC BY-SA 1.0)

The left image shows a complex mesh of several million polygons. The right image shows a drastically simplified version of the same mesh, but with a normal map applied. The normal map contains information about how the mesh should reflect light, creating the illusion of much more complex geometry.

media/material-attributes-13.png

Normal maps usually represent small changes of the normal vector (the vector which points away from the surface). Xenko uses the most common convention: the X and Y components follow the tangent and the bitangent of the surface, and the Z component follows the normal vector of the surface. This means that a value of (0, 0, 1) coincides with the normal vector and represents no change, while a value of (-1, 0, 0) tilts to the "left" (ie negative X value in the tangent (local) space).

Use a normal map texture

  1. In the asset view, select the texture you want to use as a normal map.

    Select normal map texture

  2. In the property grid, make sure the type is set to normal map.

    Normal map

    This means Xenko assumes the texture is in linear color space and converts it to a format suited for normal maps.

  3. In the asset view, select the material you want to use the normal map.

    Select material

  4. In the property grid, under the material Geometry properties, expand Surface.

    Use normal maps

  5. Next to Normal map, click Blue arrow button (Create an instance with the selected type) and make sure Texture is selected.

  6. Next to Normal map, click Hand icon (Pick an asset up).

    Select asset

  7. Select the normal map texture and click OK.

For more information about materials, see Materials.

Texture properties

Normal map textures have two properties in addition to the common texture properties.

Normal map textures

Property Description
Invert Y Have positive Y components (green pixels) face up in tangent space. This option depends on the tools you use to create normal maps.

For information about normal map properties in materials, see Materials - Geometry attributes.

See also