Can anyone shed some light on the patent status of rendering convex polygons? Last I checked, pretty much every method seemed to be patented in the US. Here, the stencil buffer method is used, which also seems to be patented, although the method was described in "OpenGL Programming Guide, 3rd Edition" from 1999, possibly earlier.
Please don't; often commercial/corporate developers are directed to never look for or reference patents in the course of their work. Especially here, it could make the difference between knowing and unknowing infringement - often a damages multiplier if it comes to a dispute. Seriously, if you have a concern I highly suggest you leave that to your legal advisors.
I am not a lawyer, and I'm certainly not your lawyer.
For example https://patents.google.com/patent/US9311738 or https://patents.google.com/patent/US7432937. The second patent mentions an alpha buffer which has stencil buffer operations instead of a stencil buffer, not sure if it matters how the thing is called. Although the second patent could maybe be worked around by incrementing the alpha buffer instead of toggling it. This would fail with polygons with a winding number higher than 256 (or 2^23 with 32 bit floating point), so good enough for almost all applications.
Several other patents can be found when searching for "patent stencil polygon", but I don't know if they are relevant or not.
