BAND.pos[:, 1] = vp.where(BELOW, -1, BAND.pos[:, 1])
# need a more physical way to make 'damped springs' than this!
BAND.p = BAND.p * DAMP
#band.p[0] = 0 # nail down left endpoint
#band.p[-1] = 0 # nail down right endpoint
BAND.pos = BAND.pos + BAND.p/M*DT
#gravity
BAND.p[:, 1] = BAND.p[:, 1] - M * G * DT
# force[n] is the force on point n from point n+1 (to the right):
LENGTH = (BAND.pos[1:] - BAND.pos[:-1])
DIST = vp.sqrt(vp.sum(LENGTH*LENGTH, -1))
FORCE = K * (DIST - RESTLENGTH)
FORCE = LENGTH/DIST[:, vp.newaxis] * FORCE[:, vp.newaxis]
BAND.p[:-1] = BAND.p[:-1] + FORCE*DT
BAND.p[1:] = BAND.p[1:] - FORCE*DT
# color based on "stretch": blue -> white -> red
C = vp.clip(DIST/RESTLENGTH * 0.5, 0, 2)
# blue (compressed) -> white (relaxed) -> red (tension)
BAND.red[1:] = vp.where(vp.less(C, 1), C, 1)
BAND.green[1:] = vp.where(vp.less(C, 1), C, 2-C)
BAND.blue[1:] = vp.where(vp.less(C, 1), 1, 2-C)
for S in SPHERES:
PTOTAL = PTOTAL+a.p
for a in ATOM:
a.p = vp.array(a.p-PTOTAL/(INDEX**2))
# Convert to tuples for faster indexing access. We aren't growing any more of them.
SPRINGS = tuple(SPRINGS)
ATOM = tuple(ATOM)
# Evaluate a couple of constants outside the loop
K_DT = K * DT
DT_M = DT / M
while True:
vp.rate(100)
for a in ATOM:
r = vp.array(a.nearpos) - a.pos
rmag = (vp.sqrt(vp.sum(vp.square(r), -1))).reshape(-1, 1) # reshape rmag from row to column
a.p += K_DT * vp.sum((1-L/rmag)*r, 0) # sum the forces k*dt*(rmag-L)*(r/rmag)
for a in ATOM:
a.pos += a.p * DT_M
for s in SPRINGS:
p1 = s.atom1.pos
r12 = s.atom2.pos-p1
direction = r12.norm()
s.pos = p1+RS*direction
s.axis = (r12.mag-2*RS)*direction
BAND.pos[:, 1] = vp.where(BELOW, -1, BAND.pos[:, 1])
# need a more physical way to make 'damped springs' than this!
BAND.p = BAND.p * DAMP
#band.p[0] = 0 # nail down left endpoint
#band.p[-1] = 0 # nail down right endpoint
BAND.pos = BAND.pos + BAND.p / M * DT
#gravity
BAND.p[:, 1] = BAND.p[:, 1] - M * G * DT
# force[n] is the force on point n from point n+1 (to the right):
LENGTH = (BAND.pos[1:] - BAND.pos[:-1])
DIST = vp.sqrt(vp.sum(LENGTH * LENGTH, -1))
FORCE = K * (DIST - RESTLENGTH)
FORCE = LENGTH / DIST[:, vp.newaxis] * FORCE[:, vp.newaxis]
BAND.p[:-1] = BAND.p[:-1] + FORCE * DT
BAND.p[1:] = BAND.p[1:] - FORCE * DT
# color based on "stretch": blue -> white -> red
C = vp.clip(DIST / RESTLENGTH * 0.5, 0, 2)
# blue (compressed) -> white (relaxed) -> red (tension)
BAND.red[1:] = vp.where(vp.less(C, 1), C, 1)
BAND.green[1:] = vp.where(vp.less(C, 1), C, 2 - C)
BAND.blue[1:] = vp.where(vp.less(C, 1), 1, 2 - C)
for S in SPHERES: