How to load and render a 3D model? C++ SDL, OpenGL

Question

I have been learning C++ for long time (but only learning game development for eight days) and I have made a simple game using 2D textures.

I was thinking of starting on 3D game development. I wanted to begin by loading and rendering a 3D model on the program, but I dont know how.

Can anybody tell me if this function could be changed to output 3D model:

GLuint loadTexture( const string &fileName )
{
SDL_Surface *image = IMG_Load( fileName.c_str() );

SDL_DisplayFormatAlpha(image);

unsigned object(0);

glGenTextures(1, &object);

glBindTexture(GL_TEXTURE_2D, object);

glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image -> w, image -> h, 0, GL_RGBA,     
GL_UNSIGNED_BYTE, image -> pixels);

//Free surface
SDL_FreeSurface(image);

Also what format should I use for this? I am using Blender, and I have seen it can export to a variety of formats. I don't know which would be the best for this kind of stuff and for serious game development.

Answer 1

Be warned that the transition into 3D graphics from 2D is much more difficult than the transition into 2D graphics initially. It is much more important to understand the fundamental mathematics involved in 3D graphics, lest you end up breaking your code in ways that won't seem to obvious. I would recommend you familiarize yourself with basic linear algebra, matrices and vectors. If you have the resources, purchasing the books "A Geometry Toolbox" and/or "Fundamentals of Computer Graphics, 3rd Ed," would be great.

That said, it sounds like the crux of your specific question has to do with loading 3D models. You won't really be able to adapt your existing texture loading function for that purpose (although you will still find texture loading useful when you want to apply textures to your models).

Blender can indeed export a variety of formats -- there is no such thing as the "best" choice here, as all options have pros and cons. Some, however, have more of one or the other. Starting out, I would recommend you try to parse and load the .obj file format. It's very straightforward, and you should be able to find a variety of example code and tutorials online to help you load it if you get stuck.

There's also the .smd file format, which is only slightly more complex and supports animation.

If you prefer to avoid writing the loaders yourself, you can use a 3rd party library like the Open Asset Importer Library.

Answer 2

This function (loadTexture()) appears to be for loading textures, not rendering 3D models.
Here is a tutorial on C++ OpenGL, it starts out basic, but goes into 3D rendering farther on in the tutorial