Picking - Harder Than It Seems

Picking isn't as easy as I thought it'd be. After further discussion and thinking about it, I've realize how big a project this. There is actually a lot more to it than just simple coordinate retrieving and coordinate conversions.

Now that I've done more reading and researching into this, there is a lot more work to do before I can complete this project. For example, from reading, I found out about the mathematics involved and the stages involved in 3D programming. The picture below shows the stages a 3D object needs to go through before it can appear as 2D object on our screen.

(Source from www.glprogramming.com)

With the vertices of a 3D object, it needs to go through the following transformation in order:
1) Viewing Transformation
2 & 3) Projection and Viewport (Any order)
4) Modeling Transformation

From understanding this, I would most likely need to go back to my 0.2 and fix some of the work. Because now that I understand these stages, I realize that what I have done, was just turned the windows coordinate of the mouse, and converted to perspective view (projection) but not 3D (modeling).

Now that I've understand theoretically what needs to be done, I need to go back, fix my mistakes, and put the rest to work.