redspark posted at 9:45PM Mon, 22 June 2020 - #4392732

Well, that would be a lot easier.

Do not mix up two things: The order of the vertices determines which side of the facet is considered 'outside' and which side is 'inside'. The normal vectors just gives the direction of the normal to the surface. If you simply invert the normal vectors by multiplying the ter s with -1, you have not changed what is outside and inside. You will probably just get weird shading. You must rebuild the polygon, or the complete geometry, with reversed vertex order.

Setting normal can serve to introduce ripples and dents in the surface, not to change orientation.