Mayo is a basic 3D viewer inspired by FreeCad.

Current features are :

• Multi-documents support, user can open many parts in the session
• Support of STEP/IGES assemblies (colors and tree structure)
• Perspective/orthographic 3D view projection
• 3D clip planes with configurable capping
• 3D view cube providing intuitive camera manipulation
• Save image(snapshot) of the current 3D view
• Editable name of STEP/IGES entities
• Editable 3D properties of the imported items, eg. material, color, display mode, ...
• Area and volume properties for meshes and shapes

3D viewer operations :

• Rotate : mouse left + move
• Pan : mouse right + move
• Zoom : mouse wheel(scroll)
• Window zoom : mouse wheel + move
• Instant zoom : space bar

Mayo requires Qt5 and OpenCascade-7.3.0 Although only tested with VC++/Windows it should build fine on Linux and MacOS.
It uses the CSF_OCCTIncludePath and CSF_OCCTLibPath environment variables to locate OpenCascade include and lib paths. On Windows these two variables are set by the env.bat script which can be found within OpenCascade's base folder. You should run this batch before building mayo :
cd .../mayo
qmake
(n)make
In case you don't want to run this file you can use the CASCADE_INC_DIR and CASCADE_LIB_DIR qmake variables instead :
qmake "CASCADE_INC_DIR=occ_include_dir" "CASCADE_LIB_DIR=occ_library_dir"

To enable optional gmio library, add this option to the qmake command line:
"GMIO_ROOT=path_to_gmio"