I added a few more 3d drawings to https://github.com/cecashon/OrderedSetVelociRaptor/blob/master/Misc/cairo_drawings/spring1.c There is a warpy perspective checkerboard, wire spheres, funnel, transparent gem with gradients, etc. The 3d eventually gets mapped to the 2d screen so you can draw 3d with cairo but there is the problem of depth testing where a background is drawn over a foreground. The funnel drawing shows this effect well. Sometimes by checking the z-values you can just draw the foreground like in the cube or ball and you might want the background and foreground both drawn like in the gem. Being able to draw 3d gives a little more flexibility with what you can draw with cairo. Makes drawing a little more fun also. I think that being able to get bezier points from a set of points along with quaternion rotation expands on what you can draw in cairo without making any internal changes. Eric