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Texture Creation

The SpeedTree® Compiler handles a lot of texture information in the course of compiling an atlas full of trees. Settings for any output textures, such as a final scalar or a maximum size allowed, can be specified on the Textures object in the Settings bar.

Texture Formats

The Compiler can convert output textures to a number of different formats, such as DDS, TGA, PNG, etc. While formats such as JPG and BMP are available, note that they will not include alpha channels.

Both compressed and uncompressed DDS textures are available. For compressed, DXT1 is used when no alpha channel is necessary, and DXT5 is used when it is. GTF (for the PS3) and GXT (for the PSP VITA) are first compressed as DDS and then converted to the output format.

Texture Atlasing

Clicking on any texture in the Atlas View will present properties for that Atlas Texture object. Textures can be scaled in X, Y, or uniform (this is prior to any rotation done for atlas layout). A border can also be added to a texture by using the “Inner scale” or “Outer margin” properties. The actual on-disk texture files used for the different layers of this Atlas Texture object are displayed in the “Texture Maps” group.

Similar to other textures, billboards can also be selected in the Atlas View. They have a subset of the properties for a regular texture, and selecting one billboard will select all of the billboards for that tree since they all need to be identical.

Texture Bleed

At runtime, textures that have been atlased can sometimes bleed through to adjacent textures on that atlas. This usually manifests itself as lines around some textures in areas that should be transparent, as seen in the following image.

To correct this, adjust the “Inner scale” or “Outer margin” properties on the offending texture to give it a border of empty space. The textures bleeding through are usually opaque (high alpha values) to the very edge of the texture, such as branch cap textures, not the textures that you see the effect on (such as leaves in the example picture).