QGIS/resources/function_help/json/single_sided_buffer

{
  "name": "single_sided_buffer",
  "type": "function",
  "groups": ["GeometryGroup"],
  "description": "Returns a geometry formed by buffering out just one side of a linestring geometry. Distances are in the Spatial Reference System of this geometry.",
  "arguments": [ {"arg":"geometry","description":"a (multi)linestring geometry"},
                 {"arg":"distance","description":"buffer distance. Positive values will be buffered to the left of lines, negative values to the right"},
                 {"arg":"segments","optional":true,"default":"8","description":"number of segments to use to represent a quarter circle when a round join style is used. A larger number results in a smoother buffer with more nodes."},
                 {"arg":"join","optional":true,"default":"1","description":"join style for corners, where 1 = round, 2 = miter and 3 = bevel"},
                 {"arg":"miter_limit","optional":true,"default":"2.0","description":"limit on the miter ratio used for very sharp corners (when using miter joins only)"}],
  "examples": [ { "expression":"single_sided_buffer($geometry, 10.5)", "returns":"line buffered to the left by 10.5 units"},
  { "expression":"single_sided_buffer($geometry, -10.5)", "returns":"line buffered to the right by 10.5 units"},
  { "expression":"single_sided_buffer($geometry, 10.5, segments:=16, join:=1)", "returns":"line buffered to the left by 10.5 units, using more segments to result in a smoother buffer"},
  { "expression":"single_sided_buffer($geometry, 10.5, join:=3)", "returns":"line buffered to the left by 10.5 units, using a beveled join"}]
}