C++ OpenGL Rendering Simple OBJ From File - c++

Question

I am currently following a basic OpenGL tutorial where the goal is to read data from an .OBJ file and then render the model. The tutorial is located here - http://www.opengl-tutorial.org/beginners-tutorials/tutorial-7-model-loading/.
Currently, my program opens the OBJ file specified and parses it using the parsing engine discussed in the tutorial here - http://www.opengl-tutorial.org/beginners-tutorials/tutorial-7-model-loading/#Reading_the_file.
The object I am trying to render is the Cube located on the same tutorial page URL.
I believe my problem lies in my display(void) function. After I execute glutDisplayFunc(display); in my main(), I am presented with a black window, rather than my rendered model.
This is my current display(void) function:
void display(void)
{
GLuint vbo;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_TRIANGLES);
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(glm::vec3) * 3, &vertices[0], GL_STATIC_DRAW);
glDrawElements(GL_TRIANGLES, vertices.size() * sizeof(glm::vec3) * 3, GL_UNSIGNED_INT, &vertices[0]);
// check OpenGL error
GLenum err;
while ((err = glGetError()) != GL_NO_ERROR)
{
printf("OpenGL error: %u", err);
}
glEnd();
glutSwapBuffers();
}
And here is the data my parser reads in, perhaps it is a parsing issue:
Success: GLEW_OK
Success: Opened OBJ File cube.obj
Read in Vertices: 1.000000, -1.000000, -1.000000
Read in Vertices: 1.000000, -1.000000, 1.000000
Read in Vertices: -1.000000, -1.000000, 1.000000
Read in Vertices: -1.000000, -1.000000, -1.000000
Read in Vertices: 1.000000, 1.000000, -1.000000
Read in Vertices: 0.999999, 1.000000, 1.000001
Read in Vertices: -1.000000, 1.000000, 1.000000
Read in Vertices: -1.000000, 1.000000, -1.000000
Read in texture coordinate: 0.748573, 0.750412
Read in texture coordinate: 0.749279, 0.501284
Read in texture coordinate: 0.999110, 0.501077
Read in texture coordinate: 0.999455, 0.750380
Read in texture coordinate: 0.250471, 0.500702
Read in texture coordinate: 0.249682, 0.749677
Read in texture coordinate: 0.001085, 0.750380
Read in texture coordinate: 0.001517, 0.499994
Read in texture coordinate: 0.499422, 0.500239
Read in texture coordinate: 0.500149, 0.750166
Read in texture coordinate: 0.748355, 0.998230
Read in texture coordinate: 0.500193, 0.998728
Read in texture coordinate: 0.498993, 0.250415
Read in texture coordinate: 0.748953, 0.250920
Read in Normals: 0.000000, 0.000000, -1.000000
Read in Normals: -1.000000, -0.000000, -0.000000
Read in Normals: -0.000000, -0.000000, 1.000000
Read in Normals: -0.000001, 0.000000, 1.000000
Read in Normals: 1.000000, -0.000000, 0.000000
Read in Normals: 1.000000, 0.000000, 0.000001
Read in Normals: 0.000000, 1.000000, -0.000000
Read in Normals: -0.000000, -1.000000, 0.000000
Reached end of file
Out Vertices Size: 234
glGetError() has not produced an error for me once, so I was not able to debug the issue that way.
Any suggestions / input?

Answer 1

None of those commands (including glGetError (...)) are valid between glBegin (...) and glEnd (...). If you move the calls to glGetError to come after glEnd, you should get GL_INVALID_OPERATION one or more times.
Remove glBegin and glEnd, they serve no purpose in this code, and only render the rest of your commands invalid.
Name
glBegin — delimit the vertices of a primitive or a group of like primitives
C Specification
void glBegin( GLenum mode);
Description
[...]
Only a subset of GL commands can be used between glBegin and glEnd. The commands are glVertex, glColor, glSecondaryColor, glIndex, glNormal, glFogCoord, glTexCoord, glMultiTexCoord, glVertexAttrib, glEvalCoord, glEvalPoint, glArrayElement, glMaterial, and glEdgeFlag. Also, it is acceptable to use glCallList or glCallLists to execute display lists that include only the preceding commands. If any other GL command is executed between glBegin and glEnd, the error flag is set and the command is ignored.
Regarding the rest of your code, you should not be generating a new buffer every frame. Do that once during initialization, add a vertex pointer, and change your draw command to glDrawArrays (...):
glDrawArrays (GL_TRIANGLES, 0, vertices.size());
glDrawElements (...) is only to be used if you have an index buffer. Unless I completely misunderstood the structure of your data, vertices is your vertex data, and does not store a list of indices.
Update 1:
After reading the tutorial your question is based on, the following changes are necessary when you load your .obj model:
GLuint buffers [3];
glGenBuffers(3, buffers);
// Position Buffer = 0
glBindBuffer(GL_ARRAY_BUFFER, buffers [0]);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(glm::vec3), &vertices[0], GL_STATIC_DRAW);
glVertexPointer (3, GL_FLOAT, 0, NULL);
// ^^^^^^^^^^^^ Sources data from VBO bound to `GL_ARRAY_BUFFER`, so a NULL pointer is OK
glEnableClientState (GL_VERTEX_ARRAY); // Use this array for drawing
// Tex Coords = 1
glBindBuffer (GL_ARRAY_BUFFER, buffers [1]);
glBufferData (GL_ARRAY_BUFFER, uvs.size () * sizeof (glm::vec2), &uvs [0], GL_STATIC_DRAW);
glTexCoordPointer (2, GL_FLOAT, 0, NULL);
glEnableClientState (GL_TEXTURE_COORD_ARRAY);
// Normals = 2
glBindBuffer (GL_ARRAY_BUFFER, buffers [2]);
glBufferData (GL_ARRAY_BUFFER, normals.size () * sizeof (glm::vec3), &normals [0], GL_STATIC_DRAW);
glNormalPointer (GL_FLOAT, 0, NULL);
glEnableClientState (GL_NORMAL_ARRAY);
Keep in mind, once you learn to use shaders, you should stop using functions such as glVertexPointer (...) and glEnableClientState (...). You will be expected to use glVertexAttribPointer (...) and glEnableVertexAttribArray (...) instead.
I wrote the code this way so you can get something up and running immediately, but it's not the modern way of writing GL software.