title: how to draw a set of coordinates in OpenGL?
body: <p>I'm trying to make Conway's Game of Life in C++, and am using OpenGL (However I'm pretty new to OpenGL) because it supports negative coordinates and therefore an infinite world.<br>
  I have a class called  GameOfLife``  which handles the entire world, and has the alive cells as [x, y] coordinates in an vector. Therefore I'm going to use a for loop throughout the alive cells coordinate and render a single pixel for each coordinate.<br>
  However whatever I have tried nothing appears on the screen no matter what I do. Below is the code with an empty <code>glBegin</code> and <code>glEnd</code> function. What should I put between these in order for it to render.</p>
  
  <p>I have tried :<br>
  dividing each coordinate by 400 to get <code>float</code> for 1 pixel .<br>
  adding 1/400 to both x and y for the third and fourth side.</p>
  
  <pre class="lang-cpp prettyprint-override"><code>#include "gol.h"
  #include &lt;GL/glew.h&gt;
  #include &lt;GLFW/glfw3.h&gt;
  int main()
  {
    std::vector&lt;std::vector&lt;int&gt;&gt; dupl;
    std::ifstream infile { "test.rle" };
    std::string file_contents { std::istreambuf_iterator&lt;char&gt;(infile), std::istreambuf_iterator&lt;char&gt;() };
    parse_rle(file_contents, 0, dupl);
    GameOfLife gol;
    gol.place_cells(dupl);
    //gol.update();
    GLFWwindow* window;
    if (!glfwInit())
      return 1;
    int width  = 400;
    window = glfwCreateWindow(width, width, "Window", NULL, NULL);
    if (!window) {
      glfwTerminate();
      return 1;
    }
    glfwMakeContextCurrent(window);
    if(glewInit()!=GLEW_OK)
      std::cout&lt;&lt;"Error"&lt;&lt;std::endl;
    glEnable(GL_DEPTH_TEST);
    while(!glfwWindowShouldClose(window)) {
      glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
      for(std::vector&lt;int&gt; i : gol.alive)
      {
          glBegin(GL_QUADS);
  
          glEnd();
      }
      glfwSwapBuffers(window);
      glfwPollEvents();
    }
    glfwTerminate();
  }
  </code></pre>