Databases
StackOverflow2013
Postsdbo
POrotation of 2d shape clockwise direction
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POrotation of 2d shape clockwise direction
    primarykey
    data
    text
    <p>I am new to python and graphics but have programmed before. According to <a href="http://en.wikipedia.org/wiki/Transformation_matrix#Rotation" rel="nofollow noreferrer">http://en.wikipedia.org/wiki/Transformation_matrix#Rotation</a> ,</p> <blockquote> <p>For rotation by an angle θ anticlockwise about the origin, the functional form is x' = xcosθ − ysinθ and y' = xsinθ + ycosθ</p> </blockquote> <p>But the following python code rotates it in the clockwise direction. Could somebody explain this?. Also translating the rectangle to the origin and back to the center seems to be an overhead. Is there any way to avoid this?. Thanks in advance.</p> <p>PS: I have looked at <code>pygame.transform.rotate</code> which does this but I would like to start from scratch to get better idea about the graphics. Is there a way to see the source of this method from python interpreter?</p> <pre><code>import pygame, sys, time from math import * from pygame.locals import * co_ordinates =((200,200),(400,200),(400,300),(200,300)) window_surface = pygame.display.set_mode((500,500),0,32) BLACK=(0,0,0) GREEN=(0,255,0) RED=(255,0,0) window_surface.fill(BLACK) ang=radians(30) """orig=pygame.draw.polygon(window_surface,GREEN,co_ordinates) n_co_ordinates = tuple([(((x[0])*cos(ang)-(x[1])*sin(ang)),((x[0])*sin(ang)+(x[1])*cos(ang))) for x in n_co_ordinates]) n_co_ordinates = tuple([((x[0]+300),(x[1]+250)) for x in n_co_ordinates]) print(n_co_ordinates) pygame.draw.polygon(window_surface,RED,n_co_ordinates)""" pygame.display.update() while True: for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() for i in range(360): ang=radians(i) if i&gt;=360: i=0 n_co_ordinates = tuple([((x[0]-300),(x[1]-250)) for x in co_ordinates]) n_co_ordinates = tuple([((x[0]*cos(ang)-x[1]*sin(ang)),(x[0]*sin(ang)+x[1]*cos(ang))) for x in n_co_ordinates]) n_co_ordinates = tuple([((x[0]+300),(x[1]+250)) for x in n_co_ordinates]) window_surface.fill(BLACK) pygame.draw.polygon(window_surface,RED,n_co_ordinates) pygame.display.update() time.sleep(0.02) </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USkennytm
    1. USpyguy12
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POrotation of 2d shape clockwise direction
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POrotation of 2d shape clockwise direction
      1. USjamast
      1. VTFavorite
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload