using win32 drawing functions be a no no ? (it does work btw). There is no h & w drawing routines other than marker, text & polyline that actually work stuff like wTriStrip, wPolygon are just empty functions that return immediately. You can convert 2d screen coords to world coords and draw there but this has issues when a scene is excessively zoomed for example.
using the GDI can work but has issues, I found a solution in the end to not having working w & h routines and issues in perspective when zoomed out. you dupe the system by setting the gw camera to an orthographic draw your stuff then return it to a persective.