import processing.opengl.*;

int iY = 0;            // also fails if type is float

void setup()
{
  size(200, 200, P3D); // works w OPENGL, fails w P3D, leaving superfluous white lines, probably numerical prob.
  stroke(0, 0, 255);
}

void draw()
{
  line(0, iY, width, iY);
  iY++;
}