Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.albasani.net!news2.arglkargh.de!feeder.erje.net!eu.feeder.erje.net!xlned.com!feeder3.xlned.com!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.017 X-Spam-Evidence: '*H*': 0.97; '*S*': 0.00; 'skip:[ 20': 0.04; 'class,': 0.07; 'assuming': 0.09; 'english,': 0.09; 'linear': 0.09; 'translate': 0.10; 'cc:addr:python-list': 0.11; 'python': 0.11; 'def': 0.12; 'windows': 0.15; '23,': 0.16; 'biology': 0.16; 'brackets,': 0.16; 'code?': 0.16; 'coordinates': 0.16; 'false:': 0.16; 'left,': 0.16; 'pygame': 0.16; 'pygame,': 0.16; 'rotation': 0.16; 'skip:[ 30': 0.16; 'weird': 0.16; 'student': 0.16; 'wrote:': 0.18; 'bit': 0.19; 'trying': 0.19; 'result.': 0.19; 'skip:p 40': 0.19; 'import': 0.22; 'cc:addr:python.org': 0.22; 'math': 0.24; "haven't": 0.24; 'cc:2**0': 0.24; 'right.': 0.26; 'excel': 0.26; 'header:In-Reply-To:1': 0.27; 'point': 0.28; 'am,': 0.29; 'points': 0.29; "doesn't": 0.30; 'skip:g 30': 0.30; 'message- id:@mail.gmail.com': 0.30; 'url:mailman': 0.30; 'program,': 0.31; '255,': 0.31; 'clock': 0.31; 'pos': 0.31; 'class': 0.32; 'probably': 0.32; 'url:python': 0.33; 'skip:# 10': 0.33; 'screen': 0.34; 'problem.': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'false': 0.36; 'done': 0.36; 'url:listinfo': 0.36; 'method': 0.36; 'url:org': 0.36; 'wrong': 0.37; 'planning': 0.38; 'skip:p 20': 0.39; 'url:mail': 0.40; 'even': 0.60; 'eventually': 0.60; 'black': 0.61; 'lower': 0.61; 'new': 0.61; 'simple': 0.61; 'first': 0.61; 'back': 0.62; 'complete': 0.62; 'p.s.': 0.66; 'subject:. ': 0.67; 'sample': 0.67; 'department.': 0.68; 'jul': 0.74; 'square': 0.74; 'upper': 0.74; 'increase': 0.74; '100': 0.79; 'center.': 0.81; 'all!': 0.84; 'calculations': 0.84; 'much,': 0.84; 'results,': 0.84; 'russia,': 0.91; '2013': 0.98 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=pOaFVgwg/8M3GpRix96xri5HlzdKOD3g3tKn+mJU19o=; b=jn/Oe+Fo3WRn6WALAwGt8OrOnzk0w7RgahT6+ZDiNZ+0MNQkmWKMeK3FsA7lrEquEl hbPffIGzegG/cY10AcuqO9A97QylhZz7VuIKwqKpBZE0Y+Bq8/IFTletJfhJ+LmPez5W bcTNxGdbR1dAzO5OOhXW+HRs547k2vwWRZB8ZK6Il0534YJE2mkWO4B8no/yVKEKG2Tf qe4N1EVonH3XyxOEG6bGt3eSdYitUmXgYZW315sL+sTMHbjY15peABUaQg+12dbBtrzo DOJUo8KHp7ijOeQja0btCk8HlPHmSECvZWYnMdykZjU8Kay9nU5a/z9t2LBjj8EgifrV VDKw== MIME-Version: 1.0 X-Received: by 10.224.135.138 with SMTP id n10mr12026310qat.96.1374584667888; Tue, 23 Jul 2013 06:04:27 -0700 (PDT) In-Reply-To: <0a905ff1-199c-4900-81e6-d9b7bb63bb44@googlegroups.com> References: <0a905ff1-199c-4900-81e6-d9b7bb63bb44@googlegroups.com> Date: Tue, 23 Jul 2013 09:04:27 -0400 Subject: Re: Beginner. 2d rotation gives unexpected results. From: David Hutto To: enmce@yandex.ru Content-Type: multipart/alternative; boundary=001a11c29762d7ec5a04e22d6ed1 Cc: python-list X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 238 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1374585070 news.xs4all.nl 15891 [2001:888:2000:d::a6]:53484 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:51085 --001a11c29762d7ec5a04e22d6ed1 Content-Type: text/plain; charset=ISO-8859-1 haven't used pygame that much, but it sounds like you drew Z. You have [0,0],[0,100],[100,0],[100, 100] 0,0 is the top left, if I recall 0, 100 would be the lower left, then you move to100, 0 which would go diagonal to the top right, and then 100,100 to the lower right, this is assuming 0,0 is the upper left. for a square you would go,[0,0],[0,100],[100,100],[100,0]then back to [0,0] to complete the square. This is assuming that 0,0 is the upper left, the coords are x,y in the brackets, and the increase in x takes you the right, and the increase in y takes you down. If that doesn't work,I'll download it later, and try it out. On Tue, Jul 23, 2013 at 8:34 AM, wrote: > Hello! > This is my first post, nice to meet you all! > I`m biology student from Russia, trying to learn python to perform some > > simple simulations. > > Here`s my first problem. > I`m trying to perform some simple 2d vector rotations in pygame, in order > > to learn the basics of linear algebra and 2d transformations. So far i > > understand matrix multiplication pretty well, and probably all my math is > > right. Eventually i`m planning to write Poly class, and use it to rotate > > and translate some simple shapes. But when i try and write it in the > > program, i get very weird results, like all points of rectangle with > > coordinates [0,0],[0,100],[100,0],[100,100] start to go spiral and > > eventually shrink to the center. Although even Excel calculations with > > this formulas give me right result. > I use Python 3.3 on Windows Xp. > What is wrong with my code? > > [code]import pygame > import math as m > > black = ( 0, 0, 0) > white = ( 255, 255, 255) > green = ( 0, 255, 0) > red = ( 255, 0, 0) > > class Poly(): > pos = [100,100] #x and y coordinates of a point > rot = m.radians(1) #rotation in degrees > def draw(self): #draw point > pygame.draw.circle(screen,white,self.pos,10,0) > def rotate(self): # rotation method > sin = m.sin(self.rot) #calculationg sin and cos > cos = m.cos(self.rot) > x_rot = int(self.pos[0]*cos-self.pos[1]*sin) #mulpitplicating > > vector to rotation matrix > y_rot = int(self.pos[0]*sin+self.pos[1]*cos) > > self.pos[0] = x_rot #set new coordinates to a point > self.pos[1] = y_rot > > a = Poly() #Some simple sample points giving rectangle > b = Poly() > c = Poly() > d = Poly() > > b.pos = [0,100] > c.pos = [100,0] > d.pos = [0,0] > > pygame.init() > size = [700,500] > screen = pygame.display.set_mode(size) > done = False > clock = pygame.time.Clock() > while done == False: > for event in pygame.event.get(): > if event.type == pygame.QUIT: > done = True > > a.rotate() #perform rotation > b.rotate() > c.rotate() > d.rotate() > > screen.fill(black) > > a.draw() #draw point > b.draw() > c.draw() > d.draw() > pygame.display.flip() > clock.tick(30) > > pygame.quit()[/code] > > P.S. Sorry for my english, bit rusty in that department. > -- > http://mail.python.org/mailman/listinfo/python-list > -- Best Regards, David Hutto *CEO:* *http://www.hitwebdevelopment.com* --001a11c29762d7ec5a04e22d6ed1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
haven't used pygame that much, but it sounds like= you drew Z. You have [0,0],[0,100],[100,0],[100,
100] 0,0 is the top left, if I recall 0, 100 would be the lower left, then you= move to100, 0 which would go diagonal to the top right, and then 100,100 t= o the lower right, this is assuming 0,0 is the upper left. for a square you= would go,[0,0],[0,100],[100,100],[100,0]then back to [0,0] to complete the= square. This is assuming that 0,0 is the upper left, the coords are x,y in= the brackets, and the increase in x takes you the right, and the increase = in y takes you down.

If that doesn't work,I'll download it later, and try it o= ut.


On Tue, Jul 23, 2013 at 8:34 AM, <enmce@yandex.ru> wrote:
Hello!
This is my first post, nice to meet you all!
I`m biology student from Russia, trying to learn python to perform some

simple simulations.

Here`s my first problem.
I`m trying to perform some simple 2d vector rotations in pygame, in order
to learn the basics of linear algebra and 2d transformations. So far i

understand matrix multiplication pretty well, and probably all my math is
right. Eventually i`m planning to write Poly class, and use it to rotate
and translate some simple shapes. But when i try and write it in the

program, i get very weird results, like all points of rectangle with

coordinates [0,0],[0,100],[100,0],[100,100] start to go spiral and

eventually shrink to the center. Although even Excel calculations with

this formulas give me right result.
I use Python 3.3 on Windows Xp.
What is wrong with my code?

[code]import pygame
import math as m

black =3D ( 0, 0, 0)
white =3D ( 255, 255, 255)
green =3D ( 0, 255, 0)
red =3D ( 255, 0, 0)

class Poly():
=A0 =A0 pos =3D [100,100] #x and y coordinates of a point
=A0 =A0 rot =3D m.radians(1) #rotation in degrees
=A0 =A0 def draw(self): #draw point
=A0 =A0 =A0 =A0 pygame.draw.circle(screen,white,self.pos,10,0)
=A0 =A0 def rotate(self): # rotation method
=A0 =A0 =A0 =A0 sin =3D m.sin(self.rot) #calculationg sin and cos
=A0 =A0 =A0 =A0 cos =3D m.cos(self.rot)
=A0 =A0 =A0 =A0 x_rot =3D int(self.pos[0]*cos-self.pos[1]*sin) #mulpitplica= ting

vector to rotation matrix
=A0 =A0 =A0 =A0 y_rot =3D int(self.pos[0]*sin+self.pos[1]*cos)

=A0 =A0 =A0 =A0 self.pos[0] =3D x_rot #set new coordinates to a point
=A0 =A0 =A0 =A0 self.pos[1] =3D y_rot

a =3D Poly() #Some simple sample points giving rectangle
b =3D Poly()
c =3D Poly()
d =3D Poly()

b.pos =3D [0,100]
c.pos =3D [100,0]
d.pos =3D [0,0]

pygame.init()
size =3D [700,500]
screen =3D pygame.display.set_mode(size)
done =3D False
clock =3D pygame.time.Clock()
while done =3D=3D False:
=A0 =A0 for event in pygame.event.get():
=A0 =A0 =A0 =A0 if event.type =3D=3D pygame.QUIT:
=A0 =A0 =A0 =A0 =A0 =A0 done =3D True

=A0 =A0 a.rotate() #perform rotation
=A0 =A0 b.rotate()
=A0 =A0 c.rotate()
=A0 =A0 d.rotate()

=A0 =A0 screen.fill(black)

=A0 =A0 a.draw() #draw point
=A0 =A0 b.draw()
=A0 =A0 c.draw()
=A0 =A0 d.draw()
=A0 =A0 pygame.display.flip()
=A0 =A0 clock.tick(30)

pygame.quit()[/code]

P.S. Sorry for my english, bit rusty in that department.
--
http://mail.python.org/mailman/listinfo/python-list



--
Best Regards,
David Hutto
<= b>CEO: http://www.hitwebdevelopment.com
--001a11c29762d7ec5a04e22d6ed1--