title: Getting scan lines of arbitrary 2d triangle
body: <p>How would one go about retrieving scan lines for all the lines in a 2D triangle?</p>
  
  <p>I'm attempting to implement the most basic feature of a 2D software renderer, that of texture mapping triangles. I've done this more times than i can count using OpenGL, but i find myself limping when trying to do it myself.</p>
  
  <p>I see a number of articles saying that in order to fill a triangle (whose three vertices each have texture coordinates clamped to [0, 1]), i need to linearly interpolate between the three points. What? I thought interpolation was between two n-dimensional values.</p>
  
  <p>NOTE; This is not for 3D, it's strictly 2D, all the triangles are arbitrary (not axis-aligned in any way). I just need to fill the screen with their textures the way OpenGL would. I cannot use OpenGL as a solution.</p>