I've just finished the next major update of the SM64 Editor, it includes many new additions such as transparent texture support. See the video description for download links.
Changes in 2.0:
[Model Conversion]
*Transparency is fully functional, use the sliders in Sketchup
*Refractive surfaces can be enabled by adding "_ref" to a material name
*Custom backgrounds are automatically resized and imported seamlessly
*Improved efficiency and speed of display list conversion
*Support for a large range of texture sizes (16x16, 8x32, 64x4, etc)
*Added automatic resizing of all incompatible texture dimensions
*Support for faces with no texture image, only a color
*Drawing layer in custom importer is chosen automatically
*Enabled death floors for custom importer
*Fixed importing of indexed textures
*Fixed some models not being centered correctly
*Fixed importing models which contain no opaque textures
[Music]
*Added ability to open Mario Kart 64 (U) ROM files and import music
*Added support for note velocity, MuseScore 2 recommended
*Added reverb setting for channels in XML converter
*Extracted sequences are also converted to a MIDI, incomplete
*Fixed low-pitch notes in XML converter
*Added option for sequences to play while the game is paused
*Fixed a bug with duplicate track names
[Interface]
*Imported level names are stored in the ROM
*Added Windows 10 support
*Various improvements to error-handling and interface
*Fixed reopening the same ROM/obj not re-reading the file
*Fixed mislabeled level/song names throughout the importer
*Fixed log files not displaying correctly in notepad
[Misc]
*Replaced M64 ROM Extender and rom_expand_64.exe with queueRAM's sm64extend.exe
*Enabled negatives for floats in the tweak editor
*Format of "Offset Polygon" property of scrolling textures starts at 0 instead of 1
Changes in 2.0:
[Model Conversion]
*Transparency is fully functional, use the sliders in Sketchup
*Refractive surfaces can be enabled by adding "_ref" to a material name
*Custom backgrounds are automatically resized and imported seamlessly
*Improved efficiency and speed of display list conversion
*Support for a large range of texture sizes (16x16, 8x32, 64x4, etc)
*Added automatic resizing of all incompatible texture dimensions
*Support for faces with no texture image, only a color
*Drawing layer in custom importer is chosen automatically
*Enabled death floors for custom importer
*Fixed importing of indexed textures
*Fixed some models not being centered correctly
*Fixed importing models which contain no opaque textures
[Music]
*Added ability to open Mario Kart 64 (U) ROM files and import music
*Added support for note velocity, MuseScore 2 recommended
*Added reverb setting for channels in XML converter
*Extracted sequences are also converted to a MIDI, incomplete
*Fixed low-pitch notes in XML converter
*Added option for sequences to play while the game is paused
*Fixed a bug with duplicate track names
[Interface]
*Imported level names are stored in the ROM
*Added Windows 10 support
*Various improvements to error-handling and interface
*Fixed reopening the same ROM/obj not re-reading the file
*Fixed mislabeled level/song names throughout the importer
*Fixed log files not displaying correctly in notepad
[Misc]
*Replaced M64 ROM Extender and rom_expand_64.exe with queueRAM's sm64extend.exe
*Enabled negatives for floats in the tweak editor
*Format of "Offset Polygon" property of scrolling textures starts at 0 instead of 1