Thanks for the questions and voicing of interest. Please kindly refer to the PDF attached; there's some tests and results and a hint of an idea I hope is a possible approach.

I'm using SketchUp as a means to test the output; in all cases the vector-data is achieved via EPS then each sample is imported into Xara for composing and exporting it all in a single sheet (the PDF).

It seems to me a solution for a 2D vector-graphic that includes shaded output (like the EPS from SkecthUp, the PDF or SVG) has to combine some form of hybrid - vector plus raster data; the vector data defines and provides the borders of the colored and shaded areas or gradient fills.

I understand this is not 'magic' - "I wish for it and it's done!", but, at least it's a direction to look forward to; I do hope it helps in this regards.

Cheers,

. Diego .