gistfile1.nim

type
  TTerrainSection* = tuple
    buffer:     PArrayBuffer
    geometry:   ref tuple [
      indices:  array[0..sectionTriangleCount-1, array[0..2, int]],
      vertices: array[0..sectionArea-1, TVec3]]
    heightmap:  ref array[0..sectionWidth-1, array[0..sectionHeight-1, uint32]]
  
  PTerrainSection* = ref TTerrainSection
  TTerrainSections* = TQuadTree[PTerrainSection]
...
proc generateVertices(section: PTerrainSection) =
  debug("Generating vertices from heightmap")
  if section.heightmap == nil: # ERROR: Type mismatch blaablablabla
    # This might attempt to read from disk in the future
    error("Heightmap was nil, this shouldn't happen!")
    raise newException(E_Base, "Heightmap was nil, this is unacceptable")
  if section.geometry.vertices != nil:
    error("Vertices are not nil, this shouldn't happen")
    raise newException(E_Base, "Vertices are not nil")