SpeedTree Engine works primarily with a new file type called STE (SpeedTree Engine), introduced in SpeedTree Cinema 8.2. STE is a special variant of SPM, designed specifically for use with SpeedTree Engine. When STE files are exported, all possible textures the tree model might use are included, which is a different set than the SPM file uses. This different (and often much larger) texture set adds:
All of these can result in a good number of additional textures, but it’s necessary in order to capture the Cinema material definitions accurately. It ensures Cinema will work correctly with external applications and renderers.
SpeedTree Engine will also load traditional SPM (SpeedTree Procedural Models) files which are the type primarily loaded and saved by SpeedTree Cinema. However, SPM files will not contain the same accurate material information that STEs do and should be avoided in cases where materials are important. Use SPM files only when geometry or hierarchy information is needed or for quick prototyping/testing.
STE files are exported from SpeedTree Cinema 8 just like the common mesh formats (e.g. FBX or Alembic) via “Export Mesh…” from the File pulldown menu entry. They will export with every texture used as well as a companion STMAT file.
Engine will also process STMAT (SpeedTree Material) files, which are straightforward XML files that contain SpeedTree material definitions. STE files always have companion STMAT files because of the extra materials created during the STE export process (e.g. material variations). SPM files, however, do not have companion STMAT files.
Engine also contains functions for reading STMAT files directly that will return an array of the materials they contain.
Note: Always prefer STE files to SPM when materials matter.