I am pulling what is left of my hair out trying to get this to work. 
Hopefully an eagle eye in here will spot my error.

I am trying to create a sweep of spheres using a spline. The sweep 
should follow along the surface of a bezier_spline lathe object.

However, none of the spline types (linear, quadratic, cubic, natural) 
seem to correspond to the bezier_spline lathe. Am I just doing something 
wrong, or are bezier splines an ommission in the spline object? And if 
they're an ommission, any suggestions for how to sweep spheres along a 
bezier spline?

Thanks!
Scott Gammans
Washington, DC

===============

//Test scene follows:

#global_settings {
     assumed_gamma 1
     max_trace_level 5
}

#declare testTexture = texture {
     pigment {color rgb 1}
}

// Here's the bezier_spline lathe along which
// I want to sweep some spheres:
lathe {
	bezier_spline
	8
	<0.0,10.0>
	<0.0,7.5>
	<1.5,7.5>
	<1.5,5.0>
	<1.5,5.0>
	<1.5,2.5>
	<0.0,2.5>
	<0.0,0.0>
	sturm
   	texture {testTexture}
	translate <0,-5,-5.5>
}

// Here's the spline, which has the same u,v points:
#local sphereSpline = spline {
	0,<0.0,10.0>
	1,<0.0,7.5>
	2,<1.5,7.5>
	3,<1.5,5.0>
	4,<1.5,5.0>
	5,<1.5,2.5>
	6,<0.0,2.5>
	7,<0.0,0.0>
}

// Linear spline definitely doesn't match:
union {
	#local ctr=0;
	#while (ctr<=7)
		sphere {sphereSpline(ctr,linear_spline),0.25}
		#declare ctr=ctr+0.01;
	#end
   	texture {testTexture}
   	rotate y*90
	translate <0,-5,-1.5>
}

// Neither does quadratic_spline:
union {
	#local ctr=0;
	#while (ctr<=7)
		sphere {sphereSpline(ctr,quadratic_spline),0.25}
		#declare ctr=ctr+0.01;
	#end
   	texture {testTexture}
   	rotate y*90
	translate <0,-5,1>
}

// Nor does cubic_spline:
union {
	#local ctr=0;
	#while (ctr<=7)
		sphere {sphereSpline(ctr,cubic_spline),0.25}
		#declare ctr=ctr+0.01;
	#end
   	texture {testTexture}
   	rotate y*90
	translate <0,-5,3.5>
}

// Nor does natural_spline:
union {
	#local ctr=0;
	#while (ctr<=7)
		sphere {sphereSpline(ctr,natural_spline),0.25}
		#declare ctr=ctr+0.01;
	#end
   	texture {testTexture}
   	rotate y*90
	translate <0,-5,6>
}

light_source {
	x*1000
	color rgb 0.25
}

camera {
	orthographic
	location x*7
	look_at 0
	angle 90
	right image_width/image_height*x
	up y
}

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