Your idea with the VertexController is something i came up with too, but it would require a complete construction of a transformation matrix for EVERY VERTEX if the method to do the projection would be as simple as project3D2D(SimpleVector...). Another option would be to transform a whole bunch of vertices with one call but this isn't cheap nor very elegant either. That, and the VertexController doesn't give you information about how the vertices are connected. So you are ending up with a soup of projected vertices but you wouldn't know how to connect them to form triangles.
To make you understand why there is no wireframe support in jPCT: There is no line-algorithm in jPCT...simply because you don't need one for the things jPCT is doing. However, there is one in Java, but i can't use it because it can't be used on a MemoryImageSource and therefor i would break 1.1 compatibility if i would use it. Another point is, that the OpenGL wireframe mode draws something like textured and lit outlines of the polygons and not just simple "white lines". To emulate this behaviour in software, i would have to use the texturemapper with a kind of degenerated triangles...i tried this once, but it didn't work too well on flat edges.
As you can see, there are some problems with wireframe... :wink:
How important is wireframe mode for your project :?:
Edit: Would it be sufficient to draw the whole scene in wireframe or are you talking about "wireframing" certain objects only?