OpenGL ES2 black screen (C++, OSX, SDL2) - c++

Question

Hate to make a "find my bug" post, but the internet seems to be severely lacking any examples for ultra-straightforward OpenGL ES2 triangle-drawing.
And technically, this is using OpenGL 2.1, but OpenGL ES2 is just a subset of that... right?
Anyways, here's my code (I stripped logging/error checking where I know it passes)
#include <SDL.h>
#include <SDL_opengl.h>
int main(int argc, char* argv[])
{
SDL_Init( SDL_INIT_VIDEO | SDL_INIT_EVENTS);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION,2);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION,1);
SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL,1);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);
SDL_Window* window = SDL_CreateWindow("Test", 0,0,100,100, SDL_WINDOW_OPENGL);
SDL_GLContext gl = SDL_GL_CreateContext(window);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
GLuint gl_program_id;
GLuint gl_vs_id;
GLuint gl_fs_id;
GLuint gl_pos_attrib_id;
GLuint gl_pos_buff_id;
char vs_file[2048]; //assume I successfully loaded vertex shader code into this array
char *vs_file_p = &vs_file[0];
char fs_file[2048]; //assume I successfully loaded fragment shader code into this array
char *fs_file_p = &fs_file[0];
gl_vs_id = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(gl_vs_id, 1, &vs_file_p, NULL);
glCompileShader(gl_vs_id);
gl_fs_id = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(gl_fs_id, 1, &fs_file_p, NULL);
glCompileShader(gl_fs_id);
gl_program_id = glCreateProgram();
glAttachShader(gl_program_id, gl_vs_id);
glAttachShader(gl_program_id, gl_fs_id);
glLinkProgram(gl_program_id);
glDeleteShader(gl_vs_id);
glDeleteShader(gl_fs_id);
glUseProgram(gl_program_id);
gl_pos_attrib_id = glGetAttribLocation(gl_program_id, "position");
float verts[] = {0.0,0.0,0.5,1.0,1.0,0.0};
glGenBuffers(1, &gl_pos_buff_id);
glBindBuffer(GL_ARRAY_BUFFER, gl_pos_buff_id);
glBufferData(GL_ARRAY_BUFFER, sizeof(float)*2*3, verts, GL_STATIC_DRAW);
glVertexAttribPointer(gl_pos_attrib_id, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(gl_pos_attrib_id);
glViewport(0,0,100,100);
glClearColor(0.,0.,0.,1.);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(gl_program_id);
glBindBuffer(GL_ARRAY_BUFFER, gl_pos_buff_id);
glBufferData(GL_ARRAY_BUFFER, sizeof(float)*2*3, verts, GL_STATIC_DRAW);
glVertexAttribPointer(gl_pos_attrib_id, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(gl_pos_attrib_id);
glDrawArrays(GL_TRIANGLES,0,3*3);
SDL_GL_SwapWindow(window);
//while loop waiting on input to quit goes here...
SDL_GL_DeleteContext(gl);
SDL_Quit();
exit(0);
return 0;
}
And my shaders are as follows:
Vertex:
#version 110
attribute vec2 position;
void main()
{
gl_Position = vec4(position,1.,1.);
}
Fragment:
#version 110
void main()
{
gl_FragColor = vec4(1.);
}
Just another note that all the shaders compile, the program compiles, the context and window creation all work without a hitch. It just ends up with a black 100x100px window. Any help would be greatly appreciated!
(also, if anyone can recommend decent, consistent, straightforward documentation sources on opengl es2 that would be awesome. So much inconsistency with docs between versions/platforms/whatever. thanks!)