i was wondering how the 3D models are actually developed? Say for example, a Rifle in a game or say an Army tank. Well, in the case of regular geometric objects, we can use equations to model (say a sphere).

But, what method is used to model such shapes?

Can anyone please throw some light on this?
Thanks.

CAD (Computer Aided Design), Modeling, and Animation software packages all have powerful facilities for generating 3D models. The trick is to somehow get them into your OpenGL code. It’s done by converting the models into a simple, format, where all surfaces are expressed as lots of tiny polygons - usually quads, and triangles. One such ‘simple’ format is Wavefront OBJ. It’s fairly straightforward to write OpenGL code that will read an OBJ file and display it as a set of polygons. You can probably find libraries that will do it. Modeling software to look at include Solidworks (CAD), Rhino (pure modeling), Maya (animation, modeling, effects), 3D Studio Max (modeling, animation), Lightwave (modeling, animation), modo (modeling), Blender (modeling, animation, it’s FREE!), and many others. Google em.