Hello again!
So I looked into your suggestion and found that you were correct! You can easily build MasterPlan with OpenGL 2 support by adding
-tags opengl21
to the `go` command. This means the run command would be:
go run -tags opengl21 ./
and the build command:
go build -tags opengl21 -ldflags -H=windowsgui -o MasterPlan.exe ./
Unfortunately, while I tried to modify the official builds to be built off of OpenGL 2.1, that caused black screens on Mac, so I can't adopt that change permanently. Sorry! I'll update the recommended system requirements for MasterPlan and see if I can update the build script to make this easier.