1. A computer implemented method, comprising: performing, by one or more computers: generating a constrained tessellation of vector artwork, wherein the vector artwork comprises one or more geometrical primitives and a fill property for each geometrical primitive, wherein each fill property specifies a fill rule and paint information, wherein the constrained tessellation comprises a plurality of tessellation primitives within a boundary; for each tessellation primitive edge representing an edge in the vector artwork, assigning to that edge a corresponding fill property from the vector artwork, and for each tessellation primitive edge not representing an edge in the vector artwork, assigning to that edge a pass-through fill rule; for a given tessellation primitive, determining an edge that is shared with an adjacent tessellation primitive for which a fill value has already been determined or is a boundary edge; evaluating the fill rule assigned to the determined edge of the given tessellation primitive, wherein said evaluating comprises: if the fill rule for the determined edge is pass-through, assigning a fill value for the given tessellation primitive to an input fill value, wherein the input fill value is the fill value of the adjacent tessellation primitive if the determined edge is shared with the adjacent tessellation primitive and is a background fill value if the determined edge is a boundary edge; and if the fill rule for the determined edge is not pass-through, assigning a fill value for the given tessellation primitive according to the fill rule of the determined edge.