海龟车的程序解释
原有的程序
globals [ sample-car ] turtles-own [ speed speed-limit speed-min ]
to setup
clear-all ask patches [ setup-road ] setup-cars watch sample-car reset-ticks
end
to setup-road ;; patch procedure
if (pycor < 2) and (pycor > -2) [ set pcolor white ]
end
to setup-cars
if number-of-cars > world-width [
user-message (word
"There are too many cars for the amount of road. Please decrease the NUMBER-OF-CARS slider to below "
(world-width + 1) " and press the SETUP button again. The setup has stopped.")
stop
]
set-default-shape turtles "car"
create-turtles number-of-cars [
set color blue
set xcor random-xcor
set heading 90
;; set initial speed to be in range 0.1 to 1.0
set speed 0.1 + random-float 0.9
set speed-limit 1
set speed-min 0
separate-cars
]
set sample-car one-of turtles
ask sample-car [ set color red ]
end
- this procedure is needed so when we click "Setup" we
- don't end up with any two cars on the same patch
to separate-cars ;; turtle procedure
if any? other turtles-here [ fd 1 separate-cars ]
end
to go
;; if there is a car right ahead of you, match its speed then slow down
ask turtles [
let car-ahead one-of turtles-on patch-ahead 1
ifelse car-ahead != nobody
[ slow-down-car car-ahead ]
[ speed-up-car ] ;; otherwise, speed up
;; don't slow down below speed minimum or speed up beyond speed limit
if speed < speed-min [ set speed speed-min ]
if speed > speed-limit [ set speed speed-limit ]
fd speed
]
tick
end
- turtle (car) procedure
to slow-down-car [ car-ahead ]
;; slow down so you are driving more slowly than the car ahead of you set speed [ speed ] of car-ahead - deceleration
end
- turtle (car) procedure
to speed-up-car
set speed speed + acceleration
end
- Copyright 1997 Uri Wilensky.
- See Info tab for full copyright and license.
定义全局变量 sample-car
定义属于海龟的变量 speed speed-limit speed-min
对于setup
将全局变量清0
要求patchs执行setup-road
setup-cars
观察 sample-car
将时钟计数器重设为0
结束
对于setup-road
在y坐标位于（-2,2）内的瓦片，设置颜色为白色
结束
对于setup-cars
如果汽车数量大于世界宽度
则执行“ 弹出用户信息，文字：There are too many cars for the amount of road. Please decrease the NUMBER-OF-CARS slider to below "(world-width
+ 1) " and press the SETUP button again. The setup has stopped
结束”
设置海龟的默认初始图形为 车
设置海龟数量“设置颜色 蓝色
设置海龟随机位置
设置海龟面向东
设置速度 speed 为0.1+0~0.9之间的随机浮点数
设置速度上限speed limit 1，下限speed min 0
seperate-cars”
设置sample car为海龟集合的随机一个
请求sample car设置颜色为红色
结束
对于seperate-cars
如果这里有了其他海龟车，那么“前进一步，separate-cars”
结束
对于go
请求海龟“让 car-ahead 是随机海龟前方一格瓦片上的海龟
如果 car-ahead 得到的不是nobody，那么减速（slow-down-car car-ahead)，否则加速(speed-up-car)
如果速度小于最小速度，那么让最小速度取代速度
如果速度大于最大速度，那么让最大速度取代速度
让海龟前进速度的步数”
时钟计数器前进1
结束
对于slow-down-car car-ahead
设置 速度speed 为 car-ahead的speed减去deceleration
对于speed-up-car
设置速度speed 为 speed加上acceleration
