如何画交通信号灯简笔画 红绿灯怎么画有立体感

是学习素描基础吗？还是彩铅？就是三个球体镶在一个长方体上...

cad画盒子怎么有立体感 画三视图，可以画上阴影 用3维视图画 直接画立体的图！ ,

画3个圈圈，分别在圈圈里涂上红黄绿。。。。。

to ex1
setpc 12
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 14
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 10
stampoval 50 50
pu home pd
end

to hld
ex1
setpc 12
fill
wait 300
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 10
fill
wait 300
pe (stampoval 48 48 "true)
pu lt 90 fd 150 rt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu home pd
hld
end
执行：hld

PC Logo 里红绿灯的编写语言如下：
to ex1
setpc 12
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 14
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 10
stampoval 50 50
pu home pd
end

to hld
ex1
setpc 12
fill
wait 300
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 10
fill
wait 300
pe (stampoval 48 48 "true)
pu lt 90 fd 150 rt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu home pd
hld
end
执行：hld