title: 3D object from vertices array
body: <p>I have recently started working in Kivy, and am trying to familiarize myself with it's capabilities. I have been looking through Kivy's API Reference, but found it not so useful.
  The only useful example of 3D rendering I found is the one that already comes with Kivy and my lack of understanding it makes it good only for .obj files. What I'm trying to accomplish is a 3D object whose vertices are generated on the fly and stored into <code>self.field.vertices</code> array.</p>
  
  <p>I attempted to modify the code, but I don't know what to do here. The code in <code>main.py</code> is almost identical to the example provided with installation, so this is only the relevant part - the one I'm having trouble with.</p>
  
  <pre><code>def setup_scene(self):
      Color(1, 1, 1, 1)
      PushMatrix()
      Translate(0, 0, -3)
      self.rot = Rotate(1, 0, 1, 0)
      UpdateNormalMatrix()
      self.mesh = Mesh(
          vertices = self.field.vertices,
          indices = range(len(self.field.vertices)//8), #no idea why this is so
          fmt = [(b"v_pos", 3, "float"), (b"v_normal", 3, "float"), (b"v_tc0", 2, "float")],
          #fmt value was copy-pasted from example's value. No idea what this is.
          mode = "triangles",
      )
      PopMatrix()
  </code></pre>
  
  <p>Can somebody please explain what value should be in <code>fmt</code>, and what is happening here in general? Thank you very much.</p>