Thanks.
So the working code is:
obj = $Ball
timeres = 1f
fn getrot t =
(
if t<=0f then return quat 0 0 0 1 -- t=0 => no rotation
t0 = t-timeres -- previous frame time
t1 = t -- current time
rot0 = getrot(t0) -- previous rotation:
p0 = at time t0 obj.position-- previous position
p1 = at time t1 obj.position-- current position
if(p0==p1) then return rot0 -- no distance is traveled
dif = p1-p0 -- difference in positions
len = Length(dif) -- distance that's traveled
vec = dif / len -- normalized movement vector.
r0 = at time t0 obj.radius -- previous radius
r1 = at time t1 obj.radius -- current radius
rotax = cross vec [0, 0, 1] -- rotation axis
angle = 360*len/((r0+r1)*pi)-- rotation amount (in degs)
rotdif = quat angle rotax -- rotation from t0 to t1
rot1 = rot0 + rotdif -- total rotation
)
getrot(currentTime)
fn getWheelRotation obj t offset:1f =
(
rot = quat 1
if t > 0f do
(
t0 = t - offset -- previous frame time
t1 = t
rot = getWheelRotation obj t0 offset:offset -- previous rotation:
p0 = at time t0 obj.position-- previous position
p1 = at time t1 obj.position-- current position
if (p0 != p1) do
(
r0 = at time t0 obj.radius -- previous radius
r1 = at time t1 obj.radius -- current radius
vec = normalize (p1 - p0) -- difference in positions
len = length (p1 - p0) -- difference in positions
axis = cross vec z_axis -- rotation axis
angle = radtodeg (len * 2 /(r0 + r1)) -- rotation amount (in degs)
turn = quat angle axis -- rotation from t0 to t1
rot += turn -- total rotation
)
)
rot
)
fn doWheelSetup obj =
(
obj.objectoffsetrot = eulerangles 90 90 0
c = obj.rotation.controller = rotation_script()
c.addnode "obj" obj
c.addconstant "offset" 1f
c.setexpression "getWheelRotation obj F offset:offset"
)
delete objects
w0 = cylinder radius:20 height:4 sides:64 slice:on slicefrom:350 pos:[0,0,20] wirecolor:green
doWheelSetup w0
w1 = cylinder radius:20 height:4 sides:64 slice:on slicefrom:350 pos:[0,0,-30] wirecolor:orange
doWheelSetup w1
animate on at time 50
(
w0.pos = [200,0,40]
w0.radius = 40
w1.pos = [300,0,-40]
w1.radius = 10
)
this is better (at least it is faster):
delete objects
gc()
w = cylinder radius:20 height:4 sides:64 slice:on slicefrom:350 pos:[0,0,20] wirecolor:green
fn setupWheelControl obj =
(
obj.objectoffsetrot = eulerangles 90 90 0
w.radius.controller = bezier_float()
cc = obj.rotation.controller = rotation_list()
c = cc.available.controller = rotation_script()
c.addconstant "step" 1f
c.addobject "radius" obj.baseobject[#radius]
c.addobject "pos" obj.controller[#position]
ss = @"
(
rot = quat 1
at time 0f
(
p0 = pos.value
r0 = radius.value
)
for t = 1f to F by step do at time t
(
p1 = pos.value
r1 = radius.value
vec = normalize (p1 - p0)
len = length (p1 - p0)
axis = cross vec z_axis
angle = radtodeg (len * 2 /(r0 + r1))
turn = quat angle axis
rot += turn
p0 = p1
r0 = r1
)
rot
)
"
c.setexpression ss
c
)
setupWheelControl w
animate on at time 100
(
w.pos = [400,0,40]
w.radius = 40
)
Hi, thanks for your input and help, but these scripts create a rolling cylinder… I’m working with a sphere that rolls in all directions on a plane.
Just looking for a way to run my existing script (which does exactly what I need) but I want to be able to drop it into the rotation controller for multiple balls and it work without me having to edit and retype the object name. Gonna be working with hundreds of balls.
my script does exactly what you need. just try to understand how it works
fn setupBallControl obj =
(
obj.radius.controller = bezier_float()
cc = obj.rotation.controller = rotation_list()
c = cc.available.controller = rotation_script()
c.addconstant "step" 1f
c.addobject "radius" obj.baseobject[#radius]
c.addobject "pos" obj.controller[#position]
ss = @"
(
rot = quat 1
at time 0f
(
p0 = pos.value
r0 = radius.value
)
for t = 1f to F by step do at time t
(
p1 = pos.value
r1 = radius.value
vec = normalize (p1 - p0)
len = length (p1 - p0)
axis = cross vec z_axis
angle = radtodeg (len * 2 /(r0 + r1))
turn = quat angle axis
rot += turn
p0 = p1
r0 = r1
)
rot
)
"
c.setexpression ss
c
)
delete objects
redraw off
(
plane name:#ground width:400 length:400 wirecolor:green
ch = Checker()
ch.coords.U_Tiling = 2
mat = Standard diffusemap:ch showinviewport:on
for k=5 to 20 do
(
at time 0 b = geosphere radius:k pos:(random [-190,-190,k] [190,190,k])
animate on at time (random 25 75) b.pos = random [-190,-190,k] [190,190,k]
animate on at time 100 b.pos = random [-190,-190,k] [190,190,k]
b.mat = mat
setupBallControl b
)
)Thanks again, but still not working
Using Max 2021 if that makes any difference.
If I put it in the script controller for rotation then I get:
Type error: Call needs function or class, got: undefined.
If I put it in in the rotation scripts of an xform in the stack (useful for later using a point cache), it states illegal self reference and actually hangs max.
Kinda out of ideas now, except the brute force rename in scripts many times.
Any last ditch ideas or suggestions?
Thanks though for all who tried.