在 pygame 中的列表上旋转

Question

If I can get some help I will post more of this code. It is a bit weird. I picked it up from a video and cleaned it up a bit. Basically it captures all the x coordinates in cam.pos[0] , all the y coordinates in cam.pos[1] , and all the z coordinates in cam.pos[2] . My 3D environment has a few dozen cubes of which I can go towards, away, above, below, to the left and to the right. But I cannot turn. This is my attempt at a corkscrew:

while True:
 dt = clock.tick()/1000
 rot = clock.tick()/1000
 r = rot*36
 for event in pygame.event.get():
     if event.type == pygame.KEYDOWN:
         if event.key == pygame.K_x:
             cam.pos[0] = cam.pos[0]*np.cos(r)-cam.pos[1]*np.sin(r)
             cam.pos[1] = cam.pos[0]*np.sin(r)-cam.pos[1]*np.cos(r)
             cam.pos[2] = cam.pos[2]
     if event.type == pygame.QUIT: pygame.quit(); sys.exit()
     if event.type == pygame.KEYDOWN:
         if event.key == pygame.K_ESCAPE: pygame.quit(); sys.exit()

     cam.events(event)
 screen.fill((0,0,0))
 face_list = []; face_color = []; depth = []
 for obj in cubes:

     vert_list = []; screen_coords = []
     for x,y,z in obj.verts:
         x-=cam.pos[0]; y-=cam.pos[1]; z-=cam.pos[2]

I can post more if anyone is interested. It does not return any errors but neither is it corkscrewing. Thanks.

Dropping in the code is not working out for some reason. You can look at it here: python_flyer

You can see I have made changes:

datax = cam.pos[0]
datay = cam.pos[1]
for i in range(datax):
for j in range(datay):
cam.pos[0] = i * np.cos(r) - j * np.sin(r)
cam.pos[1] = i * np.sin(r) - j * np.cos(r)

The error is now:

for i in range(datax):
TypeError: 'float' object cannot be interpreted as an integer

I call that progress

Answer 1

Be aware, after the line

cam.pos[0] = cam.pos[0]*np.cos(r)-cam.pos[1]*np.sin(r)

the value in cam.pos[0] is changed. So the result of

cam.pos[1] = cam.pos[0]*np.sin(r)-cam.pos[1]*np.cos(r)

depends on the calculation of the former expression.

Store the content of cam.pos to local variables, before the rotation is computed.
Further the formula for the rotation is wrong. SeeRotation matrix - In two dimensions :

 x` = x * cos(theta) - y * sin(theta) y` = x * sin(theta) + y * cos(theta)

eg

x, y, z = cam.pos    
cam.pos[0] = x * np.cos(r) - y * np.sin(r)
cam.pos[1] = x * np.sin(r) + y * np.cos(r)
cam.pos[2] = z   

---

Don't call clock.tick() twice in a row. This function returns the number of milliseconds which have passed since the previous call. So the 2nd call will always return 0.0.

Your camera position is (0, 0, -5). If this position is rotated around the z axis by any angel, then the result is still (0, 0, -5). Rotate it around the y axis.

Try the following code, which will animate your scene:

while True:
    ticks = clock.tick()
    dt = ticks/1000
    rot = ticks/1000

    r = rot
    x, y, z = cam.pos    
    cam.pos[0] = x * np.cos(r) - z * np.sin(r)
    cam.pos[1] = y 
    cam.pos[2] = x * np.sin(r) + z * np.cos(r)