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, <en...@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 = ( 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*
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