src/main/viz/pileuputils.js
function yForRow(row: number, height: number=style.READ_HEIGHT, spacing: number=style.READ_SPACING): number {
  return (row * (height + spacing));
}
function yForRow(row: number, height: number=style.READ_HEIGHT, spacing: number=style.READ_SPACING): number {
  return (row * (height + spacing));
}
Calculate row height for pileup
row: row number
height: height of elements to draw
spacing: spacing between elements to draw
Returns y location for this row