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ClipperLib

Orientation

Del.» function Orientation(const poly: TPath): boolean;

C++ » bool Orientation(const Path &poly); // Function in the ClipperLib namespace.

C#  » public static bool Orientation(Path poly); // Static method of the Clipper class in the ClipperLib namespace.

Orientation is only important to closed paths. Given that vertices are declared in a specific order, orientation refers to the direction (clockwise or counter-clockwise) that these vertices progress around a closed path.

Orientation is also dependent on axis direction:

• On Y-axis positive upward displays, Orientation will return true if the polygon's orientation is counter-clockwise.
• On Y-axis positive downward displays, Orientation will return true if the polygon's orientation is clockwise.

Notes:

• Self-intersecting polygons have indeterminate orientations in which case this function won't return a meaningful value.
• The majority of 2D graphic display libraries (eg GDI, GDI+, XLib, Cairo, AGG, Graphics32) and even the SVG file format have their coordinate origins at the top-left corner of their respective viewports with their Y axes increasing downward. However, some display libraries (eg Quartz, OpenGL) have their coordinate origins undefined or in the classic bottom-left position with their Y axes increasing upward.
• For Non-Zero filled polygons, the orientation of holes must be opposite that of outer polygons.
• For closed paths (polygons) in the solution returned by Clipper's Execute method, their orientations will always be true for outer polygons and false for hole polygons (unless the ReverseSolution property has been enabled).

See Also

Overview, Clipper.ReverseSolution, Path

Copyright ©2010-2014 Angus Johnson  -   Clipper 6.2.0   -   Help file built on 1-November-2014