[Rico]

I was playing around with the follow path tool and something came up that made me curious. So, I created and uneven ground, projected the curve onto the terrain, and had the ball follow the path. So that seemed to work pretty well with one object but, what if you wanted to do it with multiple objects.

What I mean is, what if you want 4 wheels to follow a terrain? You could duplicate the wheels and offset them but they're not all following the plane independently. So, how would you be able to accomplish this?

[dante]

what about making them follow different offset curves that are rayed onto the ground?

[Rico]

I thought about that but how can you setup 2 curves that run parallel to each other?

[dante]

convert the curve to polygons, calculate tangents on the curve via polyframe, copy lines to each point on the curve, then use an add sop to join up the lines. i'd attach a file except uploading seems totally broken on firefox.

here ... some copy pasting this to an hscript textport (in a new file)

# Automatically generated script: Monday October 19, 01:30
\set noalias = 1
set saved_path = `execute("oppwf")`
opcf /obj

# Node curve_object1 (Object/geo)
opadd -n geo curve_object1
oplocate -x 0 -y 0 curve_object1
opset -S on curve_object1
opparm curve_object1 use_dcolor ( off )
chautoscope curve_object1 +tx +ty +tz +rx +ry +rz +sx +sy +sz
opset -d on -r off -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off -x off curve_object1
opexprlanguage -s hscript curve_object1
opcf curve_object1

# Node curve1 (Sop/curve)
opadd -n curve curve1
oplocate -x 0 -y 0 curve1
opparm curve1 type ( nurbs ) coords ( '-4.29841,0,2.66208 -4.55741,0,-1.63634 -0.660205,0,-1.02699 4.1307,0,3.04724 7.60952,0,2.50708 6.31837,0,-1.45809 5.09822,0,-4.84156 ' )
opset -d off -r off -h on -f off -y off -t off -l off -s off -u off -c off -e on -b off curve1
opexprlanguage -s hscript curve1

# Node convert1 (Sop/convert)
opadd -n convert convert1
oplocate -x 0 -y -0.798701 convert1
opparm convert1 lodu ( 1 ) lodv ( 1 )
opset -d off -r off -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off convert1
opexprlanguage -s hscript convert1

# Node polyframe1 (Sop/polyframe)
opadd -n polyframe polyframe1
oplocate -x 0 -y -1.66883 polyframe1
opparm polyframe1 tangentu ( N )
opset -d off -r off -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off polyframe1
opexprlanguage -s hscript polyframe1

# Node copy1 (Sop/copy)
opadd -n copy copy1
oplocate -x -1.44156 -y -2.85065 copy1
opset -d off -r off -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off copy1
opexprlanguage -s hscript copy1

# Node line1 (Sop/line)
opadd -n line line1
oplocate -x -3.25974 -y -2.00649 line1
opparm line1 dir ( 1 0 0 ) dist ( 0.4 )
opset -d off -r off -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off line1
opexprlanguage -s hscript line1

# Node add1 (Sop/add)
opadd -n add add1
oplocate -x -1.44156 -y -3.6039 add1
opparm add1  points ( 1 ) prims ( 1 )
opparm add1 stdswitcher ( 1 1 1 ) keep ( on ) switcher ( 1 1 ) add ( skip )
opset -d on -r on -h off -f off -y off -t off -l off -s off -u off -c off -e on -b off add1
opexprlanguage -s hscript add1
oporder -e curve1 convert1 polyframe1 copy1 line1 add1 
opcf ..

opcf /obj
opcf curve_object1
opwire -n curve1 -0 convert1
opwire -n convert1 -0 polyframe1
opwire -n line1 -0 copy1
opwire -n polyframe1 -1 copy1
opwire -n copy1 -0 add1
opcf ..
opcf $saved_path

[Jim Crafton]

Rico,

I don't know if this would help, but there's a nice modeling tutorial (not free) on http://cmivfx.com/ that models a tank. The tank treads are made to follow the surface of the ground terrain but is a grid that has been subdivided, and then distorted to get a lumpy, rough feel to it. Maybe this might help?

[Tomoku]

Here is a little something to look over. Its a bit rough and needs some smoothing here and there, but you'll get the idea.

http://www.filefactory.com/file/a175...nWheels_01_rar