[vtkusers] vtkPointSpriteMapper details

[harris.pc at gmail.com]

Hi again,

I'll just continue the email thread even though this is a slightly
different issue...

My situation is I have 1 cell and lots of points.  That way I can keep
the Points array static and adjust the vertex cell array to change
what is shown.  It works well.

Because I am using vertices, it uses the VerticesMacro(), which checks
the abort count like so:

abortcount = abortcheck
for ( all cells )
{
  while ( do all points in cell )
  {
     do stuff
     if (--abortcount == 0)
       check abort
  }
}

BUT, abortcheck is set like so:
  int            abortcheck = (RenderFlags & VTK_PSM_USE_POINTS) ?
numPoints/5000 : numCells/5000;

in my case, VTK_PSM_USE_POINTS is not set, so
abortcheck = numCells / 5000

in my case, numCells = 1, so abortcheck = 0

which means it'll first decrement abortcount to -1 and keep on going
down to -A_LOT.  it'll never check for abort.

That is fine with me, I suppose.  But what confuses me is why does the
abortcount check happen in the inner loop, instead of the outer cell
look (since abortcount's unit is # of cells) ?

One idea, perhaps we should calc a p_abortcheck and an c_abortcheck,
and check for abort in the both inner and outer loops...
let p_abortcheck=numPoints/5000 and c_abortcheck=numCells/5000

That way, it'll check for abort in cases where there are lots of cells
with one-point-per-cell, and also for cases where there are
many-points-per-cell.

Or maybe always set abortcheck=numPoints/5000 and forget about numCells.

what do you think?
cheers,
Paul