OpenGL ES Highlighting Algorithm for the iPhone

I am trying to do a highlighting action on the iPhone. I can draw lines an such with the finger but now I want to be able to highlight over that. Any algorithms开发者_如何学Go out there you can point me to that does that? Using OpenGL ES off course.

Thanks

---

This should produce a pink highlight around your geometry:

render_model();
glDisable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
glColor3f(1.0f, 0.0f, 1.0f);
glLineWidth(2);
glCullFace(GL_FRONT);
render_model_using_GL_LINES();
glCullFace(GL_BACK);
glEnable(GL_TEXTURE_2D);