Jochen Lippert wrote:
 >>There was recently some mention of improved bounding for sphere_sweeps
 >>(the words "heirarchal bounding" caught my attention), but that's an
 >>unofficial patch that's being worked on. For the time being, just be
 >
 >
 > The idea behind this is to put each segment of the sweep into its own
 > bounding box. Much less space wasted, much faster calculations
 > hopefully.

Ah... I see. Yes, this sounds like a sensible approach given the
nature of the object.

  > You can have the same effect with manual bounding, but it's
  > hard to figure out the correct boxes, as you seem to have noticed. :)
 > [...]
 > That's always good. :) A simple solution for b-splines is to put every
 > four consecutive spheres of the sweep description into a box. The
 > sweep can't be outside of this box. Same goes for linear sweep and two
 > consecutive spheres. Cubic (Catmull-Rom) sweeps are much harder to
 > track, though.

Hmmm... this makes me idly ponder: until such time as there is
heirarchal bounding, perhaps one could use a macro to make
sphere_sweeps. This macro would take an array of control points and
build not one sweep but rather a lot of single segment sphere_sweeps,
duplicating control points at the appropriate places so that the ends
of the each segment smoothly connected to the next. Auto-bounding would
work it's magic on each individual segment instead of the whole group,
and the speed up effect might be comparable (?)

Don't know how much of a difference this would make in practice, but
this is an example...

// A utility macro called in Multisweep (below)
#macro _MultipleRadii(Num,RArray,This)
     #if (Num>1)
         RArray[This]
     #else
         RArray[0]
     #end
#end

// SplineType is a string, Nodes and Radii are arrays. Note, if you
// want only a uniform radius, declare one element in the Radii array.
// This would be more convenient that having to type a lot of values
// when you only want one throughout.
// Tolerance and material are a float and declared material as you'd
// expect.
#macro MultiSweep(SplineType,Nodes,Radii,Tolerance,Material)
      #ifndef(STRINGS_INC_TEMP)
          #include "strings.inc"
      #end
      #local ThisNode = 0;
      #local NodeCount = dimension_size(Nodes,1);
      #local RadCount = dimension_size(Radii,1);
      #while (ThisNode < NodeCount-3)
          sphere_sweep {
              Parse_String(SplineType)
              #if (strcmp(SplineType,"linear_spline")!=0)
                 4,
              #else
                 2,
              #end
              Nodes[ThisNode],
                       _MultipleRadii(RadCount,Radii,ThisNode)
              Nodes[ThisNode+1],
                       _MultipleRadii(RadCount,Radii,ThisNode+1)
              #if (strcmp(SplineType,"linear_spline")!=0)
                  Nodes[ThisNode+2],
                       _MultipleRadii(RadCount,Radii,ThisNode+2)
                  Nodes[ThisNode+3],
                       _MultipleRadii(RadCount,Radii,ThisNode+3)
              #end

              tolerance Tolerance
              material { Material }
          }
          #local ThisNode = ThisNode +1;
      #end
#end //Start_MultiSweep


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