spline surface demo missing half of the models

[benderscruffy]

PPSSPP v1.5.4-993-gab65c5210 Windows 64 bit
during the demo only half of the models are shown
splinesurface.zip

[LunaMoo]

Spline/Bezier curves emulation isn't perfect yet(and even worse when using hardware tesselation), so yeah, good demo for testing future improvements.;]

[unknownbrackets]

It almost seems like culling based on cw/ccw, but I double checked the flag is off. It seems to work correctly in the software renderer, and #11078 confirms that it is seeing all the points.

-[Unknown]

[unknownbrackets]

Just noting here: after #11425, this is mostly working, but there's a smallish glitch that's only visible with a hardware backend + software tessellation (which is the default setting.)

-[Unknown]