Texture MipMaps

The AVEVA™ XR engine can generate MipMaps for all types of textures, except DDS textures.

DDS textures

The AVEVA™ XR engine treats DDS texture files as definitive. It does not generate mipmaps or change their format.

Automatic generation

The automatic generation works only for generic Textures and NormalMaps. It does not work for CubeMaps or Animated Textures (FBX).

To enable automatic generation of MipMaps

• Enable the parameter mipmaps à generate in the configuration file.

Optimizing MipMap performance

Generating MipMaps can be slow, so the engine caches these results when the parameter mipmaps à enableCache is enabled.

A texture with a full chain of MipMaps occupies 33% more memory.

Possible issues with Normal Maps

• Take care when generating MipMaps from a NormalMap, because the image shrink process modifies the direction and the lengths of the Normals.

  For example, by using any kind of resample filter instead of a plain point filter we would get very different results.

  • The resample filter will "blend" the Normals giving a smoother look at the rendered pixel, but it would also remove finer details when the pixel is lit.

  • The point filter would give a raw/noisy appearance at the rendered pixel.

• Any resampling can also shorten the Normals, thus giving different results from the lighting equations; so a pixel could look less lit when the MipMap kicks in.

• The engine renormalizes Normals when the error would be very noticeable, such as during specular calculations.

• In other cases, the Normal is used as it is, such as in simple lit calculations. However, this is not a problem because the engine shaders are not created with realtime lighting in mind. At worst, a MipMapped Normal would attenuate the lighting of the pixel at distance.

Support in portable platforms

Not all pixel formats are supported in portable version. For example, single channeled textures are not currently supported in mipmap generation in portable version (such as pixel format - R8_UNORM).

Supported pixel formats in portable version for mipmap generation are as follows:

• R8G8B8A8_UNORM

• B8G8R8A8_UNORM

• B8G8R8X8_UNORM

• R8G8B8_UNORM

• B5G5R5A1_UNOR.