From e8b3db76b2a01d2eb9b65cf6323377de90b165c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9a=20Saviot?= <lea.saviot@numworks.com>
Date: Mon, 8 Apr 2019 14:53:36 +0200
Subject: [PATCH] [python/turtle] Fix rounding errors

Some horizontal/vertical lines were not properly drawn
Example script:
from math import *
from turtle import *
def a():
  def carre(n):
    fd(n)
    right(90)
    fd(n)
    right(90)
    fd(n)
    right(90)
    fd(n)
    right(90)
  penup()
  goto(-158,109)
  pendown()
  carre(100)
  for j in range(10):
    for i in range(26):
      penup()
      fd(2)
      pendown()
      carre(10)
      penup()
      fd(10)
      pendown()
    penup()
    goto(-158,109-10*(j+1))
    pendown()
---
 python/port/mod/turtle/turtle.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/python/port/mod/turtle/turtle.cpp b/python/port/mod/turtle/turtle.cpp
index 0b7dcad89..7a66d4240 100644
--- a/python/port/mod/turtle/turtle.cpp
+++ b/python/port/mod/turtle/turtle.cpp
@@ -118,8 +118,8 @@ bool Turtle::goTo(mp_float_t x, mp_float_t y) {
        * the computation of the position on the principal coordinate is done
        * using a barycenter, roundings might skip some pixels, which results in
        * a dotted line. */
-      mp_float_t currentX = principalDirection == PrincipalDirection::Y ? x * progress + oldx * (1 - progress) : oldx + (x > oldx ? i : -i);
-      mp_float_t currentY = principalDirection == PrincipalDirection::X ? y * progress + oldy * (1 - progress) : oldy + (y > oldy ? i : -i);
+      mp_float_t currentX = xLength == 0 ? x : (principalDirection == PrincipalDirection::Y ? x * progress + oldx * (1 - progress) : oldx + (x > oldx ? i : -i));
+      mp_float_t currentY = yLength == 0 ? y : (principalDirection == PrincipalDirection::X ? y * progress + oldy * (1 - progress) : oldy + (y > oldy ? i : -i));
       if (dot(currentX, currentY) || draw(false)) {
         // Keyboard interruption. Return now to let MicroPython process it.
         return true;