The keywords here are 'orthogonal' and 'orthographic'. Also found this: http://www.gamedev.net/topic/104791-last-post-about-2d-in-opengl-so-please-stop/. Hope it helps!

2D in OpenGL is just the same as 3D execpt everything has the same Z, so work on the 3D stuff (it will be useful to you in the future when you move beyond your current objective) and you're there.

Hi Kurt.
I am a hobbiest using OpenGL.

What you have to do:
First, let me tell you that most OpenGL Tutorials on the Web are outdated. Unfortunately. You should not use glVertex3f etc anymore, meaning Immediate Mode. Also, Fixed Function Pipeline, meaning OpenGL2 is outdated and should not be used anymore.
Actually, people should learn and use OpenGL3. Best way to learn OpenGL is to read the "OpenGL Superbible, 5th Edition". It covers most techniques.
To get you going, I can show you the basic things needed:

Window Manager Library, I recommend GLUT for you as Beginner or SDL 1.3 or even SFML.
While SFML cannot create a core context (which denies you using deprecated functions).

GLew or GLee. This is a library for loading extensions from the Drivers and you don't have to go through this pain.

glm. This is a math library for OpenGL, written against the Shaderspec 3.0 of OpenGL.

Now I show you in a rough overview how someone renders:
You push your data into a Vertex Buffer Object. This gets uploaded to the Videocard.
Then you tell OpenGL whats in it by defining Attribute Sets.
You can use those Attribute sets in shaders.
You should have Vertices, and TextureCoords there.
The Vertices are multiplied in the Shader with the ViewMatrix which you have to send to the Shader using OpenGL.
The matrix should be a orthographic one, if you want 2D.
This can be achieved with OpenGL and glm like this:


glm::mat4 viewmatrix = glm::ortho<float>(0.0f, x, y, 0, -1.0f, 1.0f);
int position = glGetAttribLocation(shaderID, "myProjectionMatrix");
glUniformMatrix4fv(position, 1, false, glm::value_ptr(viewmatrix ));

Note, that you need a bound shader while doing this.

Here is a basic Shader:


// Vertex Shader:

#version 330

//----------------------------------------------
// Layout Vars
//----------------------------------------------
layout(location = 0) in vec3 NL_Vertex;
layout(location = 1) in vec4 NL_Color;
layout(location = 2) in vec2 NL_TextureCoord;

//----------------------------------------------
// Uniforms from NightLight
//----------------------------------------------
uniform mat4 NL_ProjectionMatrix;

//----------------------------------------------
// Output to fragment shader
//----------------------------------------------
smooth out vec4 theColor;

void main()
{
//----------------------------------------------
// Applying position
//----------------------------------------------
gl_Position = NL_ProjectionMatrix*vec4(NL_Vertex, 1.0);

//----------------------------------------------
// Output
//----------------------------------------------
theColor = NL_Color;
}

// Fragment Shader:

#version 330

smooth in vec4 theColor;

out vec4 outputColor;

void main()
{
outputColor = theColor;
}



All it does is to apply the Viewmatrix to each Vertex and uses the colors defined in the VBO to display the object.

I hope you got a rough overview, but best thing to start learning is here:
Learning Modern 3D Graphics Programming Through OpenGL

You can also have a look into the sourcecode of my project, it uses OpenGL3 Core and is heavily documented, maybe it helps you getting an idea:
http://code.google.com/p/nightlight2d/source/browse/trunk/NightLightDLL/

I've posted video tutorials on my website that show how to get 2D and 3D working.