Hi...I've lathed a cup with a glyph spline and now I have no idea how
to shape the water object to fit into it.  Using Moray BTW and tweaking
the file manually when needed.  clipped_by and none of the CSG
operations seem to be getting me anywhere.  Any suggestions other than
folding the spline to simulate thickness and working the water from
there?

  So without further ado ...

  /*-- A Vase containg a red liquid - Demo File by K.Tyler 8/98 --*/

 // This defines the shape of the Vase and Liquid.
#declare Vase =
sor {
7,
<0.000000, 0.000000>
<0.118143, 0.000000>
<0.620253, 0.540084>
<0.210970, 0.827004>
<0.194093, 0.962025>
<0.286920, 1.000000>
<0.468354, 1.033755>}

// This Differences a Vase shape from a cube to make the Liquid
#declare Liquid =
difference {
box        { -1, 1 scale <25, 6, 25> translate 3.5*y                 }
object     { Vase inverse scale 20 } pigment { rgbf <.65,.13,.13,1>  }
finish     { ambient .5 diffuse 0 reflection .2 ior 1.66 caustics .5}}

// Then we use the same Vase shape as the container for the Liquid
#declare Water_Filled_Vase =
union  {
object { Vase scale 20 hollow on pigment { rgbf <.97,.97,.97,1 > }
finish { ambient .3 diffuse 0  specular 1 roughness .004 ior 1.66 brilliance 4}}
object { Liquid scale 1.0001 }}
// The Liquid should be scaled slightly larger than the Vase,
// to avoid the possibility of Coincident Surfaces.

// The Declared Object
object { Water_Filled_Vase translate 12.5*y}

// A Small Pedistal for the Vase
box    { -1, 1 scale<10,10,10>translate 2*y pigment{rgb .85}
finish { ambient .4 diffuse .1 reflection .15             }}

/* ---------------------------------- */

// The Camera, Lights, and other Vase object enhancing items

camera{location<0,9,-100>look_at 10*y}

light_source{<0,  4,-170>rgb 1}
light_source{<0,200,   0>rgb 1}

plane{y,0 rotate 3*x pigment { rgb .4     }
finish{ambient .4 diffuse .2 reflection .3}}

sky_sphere{
pigment{gradient y
color_map {[0 rgb .7][1 rgbf<.1,.4,.6,.8>]}}
pigment{bozo
color_map {[0 rgbf<.5,.3,.5,.6>][.5 rgbf .8][1 rgbf 1] } scale 2 }}
 

K.Tyler et, al