osrm-backend/profiles/rasterbot.lua

-- Rasterbot profile

api_version = 2

function setup()
  local raster_path = os.getenv('OSRM_RASTER_SOURCE') or "rastersource.asc"

  return {
    properties = {
      force_split_edges = true,
      process_call_tagless_node = false,
    },
    
    raster_source = raster:load(
      raster_path,
      0,    -- lon_min
      0.1,  -- lon_max
      0,    -- lat_min
      0.1,  -- lat_max
      5,    -- nrows
      4     -- ncols
    )
  }
end

-- Minimalist process_ways in order to test source_ and process_segments
function process_way (profile, way, result)
  local highway = way:get_value_by_key("highway")
  local name = way:get_value_by_key("name")

  if name then
    result.name = name
  end

  result.forward_mode = mode.cycling
  result.backward_mode = mode.cycling

  result.forward_speed = 15
  result.backward_speed = 15
end

function process_segment (profile, segment)
  local sourceData = raster:query(profile.raster_source, segment.source.lon, segment.source.lat)
  local targetData = raster:query(profile.raster_source, segment.target.lon, segment.target.lat)
  io.write("evaluating segment: " .. sourceData.datum .. " " .. targetData.datum .. "\n")
  local invalid = sourceData.invalid_data()
  local scaled_weight = segment.weight
  local scaled_duration = segment.duration

  if sourceData.datum ~= invalid and targetData.datum ~= invalid then
    local slope = (targetData.datum - sourceData.datum) / segment.distance
    scaled_weight = scaled_weight / (1.0 - (slope * 5.0))
    scaled_duration = scaled_duration / (1.0 - (slope * 5.0))
    io.write("   slope: " .. slope .. "\n")
    io.write("   was weight: " .. segment.weight .. "\n")
    io.write("   new weight: " .. scaled_weight .. "\n")
    io.write("   was duration: " .. segment.duration .. "\n")
    io.write("   new duration: " .. scaled_duration .. "\n")
  end

  segment.weight = scaled_weight
  segment.duration = scaled_duration
end

return {
  setup = setup,
  process_way = process_way,
  process_segment = process_segment
}