Quote - > Quote - so the mathematical pure sphere is in the code?

and the code tells Lux if the sphere is bigger or smaller? 

Yes in the LuxRender engine. Hit-testing a ray against a sphere (a point and a radius) is mathematically the 2nd simplest thing to execute in ray tracing. The simplest is hit-testing against an infinite plane.

Even one triangle is more complicated than a sphere. A low-poly spherical mesh is about 100 times more expensive than a sphere.

Thanks! This is an important information. Does this mean all Lux "build-in" shapes () are mathematical solutions? If yes. wouldn't it make sens to replace spotlights with a disk-shape to make the lightsource visible in the scene if checked in the GUI?

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