I am an iOS developer currently making use of SceneKit to display a COLLADA model on the screen. I am being asked to make the model look like a wireframe. It seems like I can use OpenGL shaders for this, but I have no idea how to write GLSL and had thought that something as common as a stencil/toon/edge shader would be easy to find. I haven't had much luck just Googling around unfortunately.
I am currently making use of this technique for applying shaders, but his edge shader isn't working for me. https://www.youtube.com/watch?v=yaS_BbRY0gU
Is there a common source that game developers will acquire/purchase their shaders from?
Perhaps the only thing like what you want is used by web designers/devs playing with WebGL.
http://codeflow.org/entries/2012/aug/02/easy-wireframe-display-with-barycentric-coordinates/