Finer tessellation can draw better looking shadows for circles.

    // tessellate caster outline into a 2d polygon

    Vector<Vertex> casterVertices2d;

    const float casterRefinementThresholdSquared = 20.0f; // TODO: experiment with this value

    const float casterRefinementThresholdSquared = 4.0f;

    PathTessellator::approximatePathOutlineVertices(*casterPerimeter,

            casterRefinementThresholdSquared, casterVertices2d);

    if (!ShadowTessellator::isClockwisePath(*casterPerimeter)) {