Unexpected results drawing ellipse using Python Turtle Module -


i'm trying draw ellipse using turtle module in python, plan follow:

  1. let starting point focal point of ellipse
  2. set initial theta value 0
  3. let turtle forward, let distance of forwarding a*(1-ee)/(1-emath.cos(theta))
  4. let turn around , original spot
  5. make small turn, update theta value
  6. repeat above process

here's actual code:

import turtle import math wn = turtle.getscreen() wn.bgcolor("red") my_turtle = turtle.turtle() my_turtle.penup() my_turtle.speed(9) i=0 j=0 a=200 e=0.5 x_0 = 20 theta = 0 while(i<5000):     #plotting squares     my_turtle.penup()     ellipse = a*(1-e*e)/(1-e*math.cos(theta))     my_turtle.forward(ellipse)     my_turtle.pendown()     my_turtle.forward(1)      my_turtle.left(180)     my_turtle.penup()     my_turtle.forward(ellipse+1)

however, results off this:(not complete image can see it's off)

enter image description here

can explain me wrong ? thank much!

i'm used drawing ellipses center, not 1 focal point read on ellipse math head around this. key formula appears correct:

ellipse = a*(1-e*e)/(1-e*math.cos(theta))

the issue how drawing. first need add setheading() point turtle in correct direction. (remember default it's in degrees need either convert or change turtle's default). second, how bridge between steps in drawing isn't sufficient.

i've reworked code below, , have compared center-based solution confirm generates same ellipse:

import math turtle import turtle, screen  my_screen = screen()  my_turtle = turtle(visible=false) my_turtle.speed('fastest') my_turtle.radians() my_turtle.penup()  e = 0.5  # linear eccentricity = 200  # semi major axis c = e *  # distance center focal point  my_turtle.goto(-c, 0)  # starting @ focal point there = (2 * c, 0)  # initialize previous point visited  step = 0.1  theta = step  # @ starting point, calculate next point  while theta < math.pi * 2 + step:  # overshoot close curve      # draw ellipse 1 focus point     my_turtle.setheading(theta)      distance = * (1 - e * e) / (1 - e * math.cos(theta))      my_turtle.forward(distance)     here = my_turtle.position()     my_turtle.pendown()     my_turtle.goto(there)  # draw line last position 1     my_turtle.penup()  # comment out demonstrate algorithm     my_turtle.goto(-c, 0)  # return focal point     there = here      theta += step  my_screen.exitonclick()

output

enter image description here

i left pen down illustrution it's obvious it's forming ellipse 1 focal point.


Comments

Post a Comment

Popular posts from this blog

node.js - Node js - Trying to send POST request, but it is not loading javascript content -

i have been trying send post request website, , has not been loading full site. i guessing problem node js not loading javascript content, executing it. can see javascript in response, though never loads content javascript files producing in html. what mean is, doesn't execute javascript. how make node js code overcome this, , wait the full website load? have tried native code, , "request' module, both producing same errors. if helps, don't need native javascript. modules fine. some code have tried (request module): var options = { method: 'post', uri: 'https://url', formdata: { 'email': 'email', 'prize': '0', 'transactional': 'on' }, headers: { /* 'content-type': 'application/x-www-form-urlencoded' */ // set automatically } }; rp(options) .then(function (body) { console.log(body) }) .catch(function (err) { console.log(err) }); when fetch content...
Read more

javascript - Replicate keyboard event with html button -

i have tried few ways make happen. have javascript pinball game uses keyboard keys controls. converting application touch screen display. workaround, hoping overlay buttons when clicked simulate keyboard strokes. have done research , sounds should work. using jquery v3.2.1 here things have tried far... html element: <input type="button" class="coil"></input> $('.coil').trigger({type: 'keydown', which: 40, keycode: 40}); with this, not errors, nothing happens. var coilkey = $('body').keydown(function(e) { switch (e.keycode) { case 40: break;} }) $('.coil').click(coilkey); this 1 returns error in console... ((jquery.event.special[handleobj.origtype] || (intermediate value)).handle || handleobj.handler).apply not function below javascript game engine handles key listeners... addkeylistener: function (keyandlistener) { this.keylisteners.push(keyandlistener); }, // gi...
Read more

javascript - Web audio api 5.1 surround example not working in firefox -

i've been playing lott lately web audio api on both firefox , chrome. few days ago started experiment surround set. when trying surround audio in web audio api came notice example works fine in chrome v59 not in firefox v54. // create web audio api context var audioctx = new (window.audiocontext || window.webkitaudiocontext)(); audioctx.destination.channelinterpretation = 'discrete'; audioctx.destination.channelcountmode = 'explicit'; audioctx.destination.channelcount = 6; var oscillators = []; var merger = audioctx.createchannelmerger(6); console.log(audioctx.destination, merger); //merger.channelinterpretation = 'discrete'; //merger.channelcountmode = 'explicit'; //merger.channelcount = 6; var addoscilator = function(channel, frequency) { var oscillator = audioctx.createoscillator(); oscillator.frequency.value = frequency; // value in hertz oscillator.connect(merger,0,channel); oscillator.start(); oscillators.push(o...
Read more