Reading in a .obj file

OpenGL OpenGL: Basic Coding
1

I’m using Microsoft Visual Studio with OpenGL/C++.
I’ve been searching the web for days on tutorials, but there doesn’t seem to be any that still work / that I can follow and get working.

I’m just trying to display a Cube for now, but can’t seem to read in the correct values T_T.

I’m currently reading in Colours, Vertices, and Indices from my own created file, and drawing Polygons to make a cube, but I can’t seem to expand this to the format of a .obj file.

Here’s what I currently have:

int read_file (const string fileName)
{
	ifstream inFile;
	inFile.open(fileName.c_str());

	inFile >> NUM_VERTS;
	vertices = new point3D[NUM_VERTS];

	for (int i=0; i < NUM_VERTS; i++)
	{	
		inFile >> vertices[i].x;
		inFile >> vertices[i].y;
		inFile >> vertices[i].z;
	}

	inFile >> NUM_COL;
	colours = new colour[NUM_COL];

	for (int i=0; i < NUM_COL; i++)
	{
		inFile >> colours[i].r;
		inFile >> colours[i].g;
		inFile >> colours[i].b;
	}

	inFile >> NUM_POLY;
	indices = new polygon[NUM_POLY];

	for (int i=0; i < NUM_POLY; i++)
	{
		inFile >> indices[i].a;
		inFile >> indices[i].b;
		inFile >> indices[i].c;
	}

	inFile.close();
	return 0;
}

void drawCube()
{
	for (int i = 0; i < NUM_POLY; i++)
	{ 
		glColor3f(colours[i].r, colours[i].g, colours[i].b); 
		drawPolygon(indices[i].a, indices[i].b, indices[i].c); 
  	} 
}


void drawPolygon(int a, int b, int c)
{
glBegin(GL_TRIANGLES);
	glVertex3fv(&vertices[a].x);                 //Top
    glVertex3fv(&vertices[b].x);                 //Bottom left
	glVertex3fv(&vertices[c].x);                 //Bottomg right

	glEnd();  
}

Any help would be massively appreciated, as I’m really confused.

2

Irrelevant to the above code:
I hate to recommend another file format, but it does offer a much wider range implementation, and is extremely simple to parse.

The Collada file format uses the XML schema, and once you understand Collada, or XML, you can use a parser such as TinyXML to write and read other data files, such as config files, and other user-defined variables including models.

Relevant to your code:
As for your code, tell it to print everything it’s getting.
Then reference the outputted data with the file’s data.
Make sure everything is getting read right.
(may use cout, I prefer printf("%s
",Data); )

Debugging is a very nice thing to have.

Also, is your OpenGl version set below 3.2?
If not, glVertex3f may not work, as it has been removed from 3.2 forward.

3

I have GL 3.3 and every old program works fine.
All the old GL functions are still there and will be there forever.