-these needed to specify a set of metaballs. There was a bit of
-ambiguity here as the paper just states ``the continuous density
-distribution is expressed by a set of metaballs'', so from the
-implementation in~\cite{dobashi1998animation} I interpreted this as a
-fixed grid of metaballs at each point, assigning a density to each one.
-
-One of the biggest challenges I faced when interpreting the paper, was
-figuring out how the billboard textures are precalculated. The paper
+they need to be mapped to metaballs that can be rendered. There was a
+bit of ambiguity here as the paper just states ``the continuous
+density distribution is expressed by a set of metaballs'', so given
+the implementation in~\cite{dobashi1998animation}, I interpreted this
+as a fixed grid of fixed-sized metaballs at each point, with a density
+assigned to each one.
+
+One of the biggest challenges I faced when interpreting the paper was
+figuring out how the billboard textures were precalculated. The paper