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@gyubeomim
Created December 29, 2021 22:52
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VPython example 5
# code from https://youtu.be/oMBohUQz3NI
from vpython import * # 7.6.2
from math import *
#------------------------------------------------------------------
# 그래픽 그려주는 코드
#------------------------------------------------------------------
# 그래픽창을 생성합니다
scene = canvas(width=800, height=300, center=vector(0,0,0))
# 3개의 물체를 생성합니다. 거리는 5m 간격으로 일정합니다
block1 =box(pos=vector(-5,0,0), size=vector(2,2,2), color=color.blue, opacity=0.7)
block2 = box(pos=vector(0,0,0), size=vector(2,2,2), color=color.blue, opacity=0.7)
block3 = box(pos=vector(5,0,0), size=vector(2,2,2), color=color.blue, opacity=0.7)
# 바닥 생성
bottom = box(pos=vector(0,-1.25,0), size=vector(20.5,0.5,7))
# 벽 생성
wall1 = box(pos=vector(-10,1,0), size=vector(0.5,4,7))
wall2 = box(pos=vector(10,1,0), size=vector(0.5,4,7))
# 스프링 생성
spring1 = helix(pos=vector(-10,0,0), axis=vector(7,0,0), radius=0.5, coils=8, thickness=0.1, color=color.gray(0.5))
spring2 = helix(pos=block1.pos, axis=vector(7,0,0), radius=0.5, coils=8, thickness=0.1, color=color.gray(0.5))
spring3 = helix(pos=block2.pos, axis=vector(7,0,0), radius=0.5, coils=8, thickness=0.1, color=color.gray(0.5))
spring4 = helix(pos=block3.pos, axis=vector(7,0,0), radius=0.5, coils=8, thickness=0.1, color=color.gray(0.5))
x1 = 3. # 초기 위치
x2 = 0.
x3 = 0.
k = 10. # 강성
m = .5 # 질량
v1 = 0. # 초기속도
v2 = 0.
v3 = 0.
#------------------------------------------------------------------
# 애니메이션 코드
#------------------------------------------------------------------
t = 0
dt = 0.01
label1 = label()
label2 = label()
label3 = label()
while True:
rate(100) # 100 Hz, 초당 100번씩 루프를 돌고 dt=0.01이므로 시간 t는 실제 시간과 일치합니다
t += dt
# 운동방정식을 통해 a1,a2,a3를 구하고 v,x로 적분합니다
a1 = k/m*(x2 - 2*x1)
a2 = k/m*(x3 - 2*x2 + x1)
a3 = k/m*(-2*x3 + x2)
v1 += a1*dt
v2 += a2*dt
v3 += a3*dt
x1 += v1*dt
x2 += v2*dt
x3 += v3*dt
# 블락의 실시간 위치를 갱신합니다
block1.pos.x = x1-5
block2.pos.x = x2
block3.pos.x = x3+5
# 스프링 또한 블락과 같이 이동합니다
# pos : 스프링 좌측의 좌표
spring2.pos = block1.pos
spring3.pos = block2.pos
spring4.pos = block3.pos
# axis : 스프링 우측의 좌표
spring1.axis.x = block1.pos.x - wall1.pos.x
spring2.axis.x = block2.pos.x - block1.pos.x
spring3.axis.x = block3.pos.x - block2.pos.x
spring4.axis.x = wall2.pos.x - block3.pos.x
label1.pos = wall2.pos + vector(0.1,-3,0)
label1.text = 'time : %.2f s' % t
label2.pos = wall2.pos + vector(0.1,-4.3,0)
label2.text = 'mass : %.1f kg' % m
label3.pos = wall2.pos + vector(0.1,-5.6,0)
label3.text = 'k : %.2f N/m' % k
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