<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:small"><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jun 19, 2018 at 11:20 AM, Andre Roberge <span dir="ltr"><<a href="mailto:andre.roberge@gmail.com" target="_blank">andre.roberge@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div style="font-family:arial,helvetica,sans-serif;font-size:small">

<div style="text-decoration-style:initial;text-decoration-color:initial">Is this Python's edu-sig or Monty Python's philosophers club?  ;-) ;-) ;-) </div><div style="text-decoration-style:initial;text-decoration-color:initial"><br></div></div></div></blockquote><div><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">​I do think we're branching out to discuss coordinate systems more generally, as a perennial feature of pedagogy.</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">These more general concerns are distinct from turtle.py in particular.  <br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">I hope contributors are not shy about continuing the higher level discussions.<br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">​</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div style="font-family:arial,helvetica,sans-serif;font-size:small"><div style="text-decoration-style:initial;text-decoration-color:initial">Anyone on this list could probably do the following in less than one minute...</div><div style="text-decoration-style:initial;text-decoration-color:initial"><br></div></div></div></blockquote><div><br></div><div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">​Yes, I just ran the following:</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">>>> turtle.setworldcoordinates(0, -200, 400, 0)<br>>>> turtle.forward(100)<br>>>> turtle.right(90)<br>>>> turtle.forward(100)<br>>>> turtle.left(90)<br>>>> turtle.forward(100)<br>>>> <br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">Here's the resulting graphic output:</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><a href="https://flic.kr/p/28i3cDY">https://flic.kr/p/28i3cDY</a><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">However in this test, I did not isolate the problem.  The turtle turns to its own right and then its own left.</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">I'm assuming lower left is (0, -200) and upper right is (400, 0) i.e. Y still increases as we go vertically towards the top.</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">I should change that...</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">Lets make Y increasingly positive as we go down the screen.<br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">>>> turtle.setworldcoordinates(0,200,400,0)<br>>>> turtle.forward(100)<br>>>> turtle.left(90)<br>>>> turtle.forward(100)<br>>>> turtle.right(90)<br>>>> turtle.forward(100)<br>>>> turtle.right(90)<br><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">Indeed, now I see the problem.  The turtle no longer obeys it's own viewpoint but turns oppositely to what I command.</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">Here's the graphic output this time:</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><a href="https://flic.kr/p/26ZJmQ2">https://flic.kr/p/26ZJmQ2</a><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">Kirby</div><div style="font-family:arial,helvetica,sans-serif;font-size:small" class="gmail_default">​</div><br></div></div></div></div>