SDL & Glew - Draw tringle, rectangle

#include "SDL/SDL.h"
#include "GL/glew.h"

#include <iostream>

bool processInput();
void draw(SDL_Window *window);
void draw_square_over(float x, float y, float size);
void draw_square(float x, float y, float size);
void draw_background();

int main(int argc, char* argv[])
{
    SDL_Init(SDL_INIT_EVERYTHING);

    SDL_Window *window = SDL_CreateWindow("My Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1024, 768, SDL_WINDOW_OPENGL);
    if (!window)
        return 1;
    SDL_GLContext glContext = SDL_GL_CreateContext(window);
    if (!glContext)
        return 2;
    GLenum error = glewInit();
    if (error != GLEW_OK)
        return 3;

    glClearDepth(1.0);
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

    bool run = true;
    while (run)
    {
        run = processInput();
        draw(window);
    }

    SDL_GL_DeleteContext(glContext);
    SDL_DestroyWindow(window);

    return 0;
}

bool processInput()
{
    SDL_Event event;
    while (SDL_PollEvent(&event))
    {
        switch (event.type)
        {
        case SDL_QUIT: return false;
        case SDL_MOUSEMOTION:
            std::cout << "Mouse moved to: " << event.motion.x << " " << event.motion.y << std::endl; return true;
        }
    }

    return true;
}

inline void draw_triangle()
{
    glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

    glBegin(GL_TRIANGLES);
    glColor3f(1.0f, 0.0f, 0.0f);    // red
    glVertex2f(-1.f, -1.f);
    glColor3f(0.0f, 1.0f, 0.0f);    // blue
    glVertex2f(1.f, -1.f);
    glColor3f(0.0f, 0.0f, 1.0f);    // green
    glVertex2f(1.f, 1.f);
    glEnd();
}

inline void draw_background() {
    draw_square_over(0.f, 0.f, 2.f);
}

void draw_square(float x, float y, float size) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    draw_square_over(x, y, size);
}

void draw_square_over(float x, float y, float size) {
    struct {
        float x, y;
    } BL; // bottom-left

    BL.x = x - size/2;
    BL.y = y - size/2;

    glBegin(GL_QUADS);
    glColor3d(1, 0, 0);
    glVertex3f(BL.x, BL.y, 0.0f);  // bottom-left
    glColor3d(1, 1, 0);
    glVertex3f(BL.x + size, BL.y, 0.0f);  // bottom-right
    glColor3d(1, 1, 1);
    glVertex3f(BL.x + size, BL.y + size, 0.0f);  // top-right
    glColor3d(0, 1, 1);
    glVertex3f(BL.x, BL.y + size, 0.0f);   // top-left
    glEnd();
}

void draw(SDL_Window *window)
{
    draw_background();
    draw_square_over(0.f, 0.f, 0.2f);
    SDL_GL_SwapWindow(window);
}