Python游戏编程入门4

Math和Graphics:Analog Clock示例程序
本章介绍Python的math模块，该模块可以执行计算，如常见的三角正弦函数、余弦函数、正切函数等。

使用正弦和余弦函数绘制圆
创建Anlog Clock示例程序

关于math模块
https://docs.python.org/3/library/math.html
https://docs.python.org/2.7/library/math.html

math.cos(x)
Return the cosine of x radians.

math.sin(x)
Return the sine of x radians.

math.tan(x)
Return the tangent of x radians.

math.degrees(x)
Convert angle x from radians to degrees.

math.radians(x)
Convert angle x from degrees to radians.

math.pi
The mathematical constant π = 3.141592..., to available precision.

math.e
The mathematical constant e = 2.718281..., to available precision.

注意：
对于负数的取模
余数应该是大于等于0小于该数绝对值的那个数,比方说（-5）%3=1,认为-5=3*(-2)+1

书中给出的示例可以优化。

Draw circle in hard way

import sys,pygame,math,random
from pygame.locals import *
pygame.init()

screen=pygame.display.set_mode((600,500))
pygame.display.set_caption("Circle Demo")
angle=0
color=random.randint(0,255),random.randint(0,255),random.randint(0,255)
while True:
   for event in pygame.event.get():
       if event.type==QUIT:
           sys.exit()
   keys=pygame.key.get_pressed()
   if keys[K_ESCAPE]:
       sys.exit()

   screen.fill((255,255,255))

x=300
   y=250
   radius=200


   circle_x=x+radius*math.cos(math.radians(angle))
   circle_y=y+radius*math.sin(math.radians(angle))

pygame.draw.circle(screen,color,(int(circle_x),int(circle_y)),10,0)
   angle+=1
   if angle>359:
       color=random.randint(0,255),random.randint(0,255),random.randint(0,255)
       angle=0

   pygame.display.update()

Anlog Clock示例程序

import sys,datetime,pygame,math
from pygame.locals import *
from datetime import datetime,date,time
pygame.init()
def print_text(font,x,y,text,color=(255,255,255)):
imgtext=font.render(text,True,color)
screen.blit(imgtext,(x,y))

def wrap_angle(angle):
return angle%360

#main program begins
screen=pygame.display.set_mode((600,500))
pygame.display.set_caption("Anlog Clock Demo")
font=pygame.font.Font(None,36)
orange=220,180,0
white=255,255,255
yellow=255,255,0
pink=255,100,100

pos_x=300
pos_y=250
radius=250
angle=360

#repeating loop
while True:
   for event in pygame.event.get():
       if event.type==QUIT:
           sys.exit()
   keys=pygame.key.get_pressed()
   if keys[K_ESCAPE]:
       sys.exit()

   screen.fill((0,0,100))
   #draw one step around the circle
   pygame.draw.circle(screen,white,(pos_x,pos_y),radius,6)

   #draw the clock numbers1-12
   for n in range(1,13):
       angle=math.radians(n*30-90)
       x=(radius-20)*math.cos(angle)+pos_x-10
       y=(radius-20)*math.sin(angle)+pos_y-10
       print_text(font,int(x),int(y),str(n))

   #get the time of day
   today=datetime.today()
   hours=today.hour%12
   minutes=today.minute
   seconds=today.second

   #draw the hours hand
   hour_angle=wrap_angle(hours*30-90)
   hour_angle=math.radians(hour_angle)
   hour_x=pos_x+math.cos(hour_angle)*(radius-80)
   hour_y=pos_y+math.sin(hour_angle)*(radius-80)
   target_h=(int(hour_x),int(hour_y))
   pygame.draw.line(screen,pink,(pos_x,pos_y),target_h,25)

   #draw the minutes hand
   minute_angle=wrap_angle(minutes*6-90)
   minute_angle=math.radians(minute_angle)
   minute_x=pos_x+math.cos(minute_angle)*(radius-60)
   minute_y=pos_y+math.sin(minute_angle)*(radius-60)
   target_m=(int(minute_x),int(minute_y))
   pygame.draw.line(screen,orange,(pos_x,pos_y),target_m,12)

   #draw the seconds hand
   second_angle=wrap_angle(seconds*6-90)
   second_angle=math.radians(second_angle)
   second_x=pos_x+math.cos(second_angle)*(radius-40)
   second_y=pos_y+math.sin(second_angle)*(radius-40)
   target_s=(int(second_x),int(second_y))
   pygame.draw.line(screen,yellow,(pos_x,pos_y),target_s,6)

   #cover the center
   pygame.draw.circle(screen,white,(pos_x,pos_y),20)

print_text(font,0,0,str(hours)+":"+str(minutes)+":"+str(seconds))

pygame.display.update()

wrap_angle函数是多余的，因为在三角函数的运算中+-360°对于结果没有影响。
去除所有带有 wrap_angle()的部分，程序运行正常。

1、修改circle程序，以使得在每个角度绘制不同的形状，而不是绘制一个小的填充的圆。
import sys,pygame,math,random
from pygame.locals import *
pygame.init()

x=300
   y=250
   radius=200


   circle_x=int(x+radius*math.cos(math.radians(angle)))
   circle_y=int(y+radius*math.sin(math.radians(angle)))

   if angle%3==0:
       pygame.draw.circle(screen,color,(circle_x,circle_y),12)
   elif angle%3==1:
       pygame.draw.rect(screen,color,(circle_x-10,circle_y-10,20,20))
   elif angle%3==2:
       pygame.draw.ellipse(screen,color,(circle_x-15,circle_y-10,30,20))

angle+=1
   if angle>359:
       color=random.randint(0,255),random.randint(0,255),random.randint(0,255)
       angle=0

   pygame.display.update()

感觉画了一个会蠕动的小东西，有一点意思。

2、Analog Circle变得更好看些。这个我没去实现，我把时针的角度做了微调，感觉更符合习惯。现在
时针不会一直指向整点的位置了，而是会根据分钟数指向两个整点之间。
import sys,datetime,pygame,math
from pygame.locals import *
from datetime import datetime,date,time
pygame.init()
def print_text(font,x,y,text,color=(255,255,255)):
imgtext=font.render(text,True,color)
screen.blit(imgtext,(x,y))

def wrap_angle(angle):
return angle%360

pos_x=300
pos_y=250
radius=250
angle=360

#repeating loop
while True:
   for event in pygame.event.get():
       if event.type==QUIT:
           sys.exit()
   keys=pygame.key.get_pressed()
   if keys[K_ESCAPE]:
       sys.exit()

   screen.fill((0,0,100))
   #draw one step around the circle
   pygame.draw.circle(screen,white,(pos_x,pos_y),radius,6)

   #draw the clock numbers1-12
   for n in range(1,13):
       angle=math.radians(n*30-90)
       x=(radius-20)*math.cos(angle)+pos_x-10
       y=(radius-20)*math.sin(angle)+pos_y-10
       print_text(font,int(x),int(y),str(n))

   #get the time of day
   today=datetime.today()
   hours=today.hour%12
   minutes=today.minute
   seconds=today.second

   #draw the hours hand
   hour_angle=wrap_angle(hours*30-90+minutes*0.5) #对比原来的程序修改了这一行。
   hour_angle=math.radians(hour_angle)
   hour_x=pos_x+math.cos(hour_angle)*(radius-80)
   hour_y=pos_y+math.sin(hour_angle)*(radius-80)
   target_h=(int(hour_x),int(hour_y))
   pygame.draw.line(screen,pink,(pos_x,pos_y),target_h,25)

   #draw the minutes hand
   minute_angle=wrap_angle(minutes*6-90)
   minute_angle=math.radians(minute_angle)
   minute_x=pos_x+math.cos(minute_angle)*(radius-60)
   minute_y=pos_y+math.sin(minute_angle)*(radius-60)
   target_m=(int(minute_x),int(minute_y))
   pygame.draw.line(screen,orange,(pos_x,pos_y),target_m,12)

   #draw the seconds hand
   second_angle=wrap_angle(seconds*6-90)
   second_angle=math.radians(second_angle)
   second_x=pos_x+math.cos(second_angle)*(radius-40)
   second_y=pos_y+math.sin(second_angle)*(radius-40)
   target_s=(int(second_x),int(second_y))
   pygame.draw.line(screen,yellow,(pos_x,pos_y),target_s,6)

   #cover the center
   pygame.draw.circle(screen,white,(pos_x,pos_y),20)

print_text(font,0,0,str(hours)+":"+str(minutes)+":"+str(seconds))

pygame.display.update()

看起来更符合习惯了。至于美观的要求就算了。

巴特西

Python游戏编程入门4

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