Problem:
Celestia v1.6 (and v1.5.1) assumes that dxt3 and dxt5 textures are transparent
even if they are opaque. This causes depth sorting problems.
Suggestion:
Celestia should examine dxt5 and dxt3 files to see if they
should be treated as opaque or transparent.
This problem is demonstrated at the URL below. It shows the hub of a toroidal space station being drawn in front of the torus. The hub should be partially obscured by the torus.
When a png texture with no alpha channel is used, the space station is drawn correctly.
The model specifies a surface texture named metallic96.*, so any image type can be used with it.
/textures/medres includes the script make_dds.sh which can used to convert jpg to png to dxt5 for testing. The files metallic96_mine.jpg and .png could be renamed to be metallic96.jpg or .png to see the model drawn correctly.
The script requires Cygwin, imagemagick and Nvidia's legacy DDS utilities.