Foo

#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#define STB_TRUETYPE_IMPLEMENTATION
#include <stb_truetype.h>

unsigned char ttf_buffer[1 << 20];
unsigned char temp_bitmap[512 * 512];

stbtt_bakedchar cdata[96]; // ASCII 32..126 is 95 glyphs
GLuint ftex;

void my_stbtt_initfont() {
    fread(ttf_buffer, 1, 1 << 20, fopen("/System/Library/Fonts/Supplemental/Arial Unicode.ttf", "rb"));
    stbtt_BakeFontBitmap(ttf_buffer,0, 32.0, temp_bitmap,512,512, 32,96, cdata); // no guarantee this fits!
    // can free ttf_buffer at this point
    glGenTextures(1, &ftex);
    glBindTexture(GL_TEXTURE_2D, ftex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, 512,512, 0, GL_ALPHA, GL_UNSIGNED_BYTE, temp_bitmap);
    // can free temp_bitmap at this point
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
}

void my_stbtt_print(float x, float y, char *text) {
    // assume orthographic projection with units = screen pixels, origin at top left
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, ftex);
    glBegin(GL_TRIANGLE_FAN);
    while (*text) {
        if (*text >= 32 && *text < 127) {
            stbtt_aligned_quad q;
            stbtt_GetBakedQuad(cdata, 512,512, *text - 32, &x, &y, &q,1);//1=opengl & d3d10+,0=d3d9
            glTexCoord2f(q.s0,q.t1); glVertex2f(q.x0,q.y0);
            glTexCoord2f(q.s1,q.t1); glVertex2f(q.x1,q.y0);
            glTexCoord2f(q.s1,q.t0); glVertex2f(q.x1,q.y1);
            glTexCoord2f(q.s0,q.t0); glVertex2f(q.x0,q.y1);
            glTexCoord2f(q.s0,q.t1); glVertex2f(q.x0,q.y0);
        }
        ++text;
    }
    glEnd();
}

void drawQuad(float const& x, float const& y, float const& w, float const& h) {
    glBegin(GL_TRIANGLE_FAN); {
        glVertex2f(x, y);
        glVertex2f(x + w, y);
        glVertex2f(x + w, y + h);
        glVertex2f(x, y + h);
        glVertex2f(x, y);
    } glEnd();
}

int main() {
    if (!glfwInit()) {
        std::cerr << "unable to init glfw" << std::endl;
        return 1;
    }
    glfwSetErrorCallback([](int e, char const* msg) {
        std::cerr << "[ERROR] (" << e << "): " << msg << std::endl;
    });
    glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
    auto window = glfwCreateWindow(400, 400, "Foo", nullptr, nullptr);
    glfwMakeContextCurrent(window);
    if (glewInit() != GLEW_OK) {
        std::cerr << "unable to init glew" << std::endl;
        glfwTerminate();
        return 1;
    }
    glfwSwapInterval(1);
    glViewport(0, 0, 400, 400);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    my_stbtt_initfont();
    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0.0f, 400, 0, 400, 0.0f, 1.0f);
        glColor3f(1, 0, 0);
        drawQuad(300, 300, 100, 100);
        my_stbtt_print(100, 100, (char*) "Foo Bar Foo Bar");
        glfwPollEvents();
        glfwSwapBuffers(window);
    }
    glfwTerminate();
    return 0;
}