Package com.github.micycle1.clipper2.offset

Class ClipperOffset

java.lang.Object
com.github.micycle1.clipper2.offset.ClipperOffset
public class ClipperOffset extends Object
Manages the process of offsetting (inflating/deflating) both open and closed paths using different join types and end types.

Geometric offsetting refers to the process of creating parallel curves that are offset a specified distance from their primary curves.

Library users will rarely need to access this class directly since it's generally easier to use the inflatePaths() function for polygon offsetting.

Notes:

  • When offsetting closed paths (polygons), a positive offset delta specifies how much outer polygon contours will expand and inner "hole" contours will contract. The converse occurs with negative deltas.
  • You cannot offset open paths (polylines) with negative deltas because it's not possible to contract/shrink open paths.
  • When offsetting, it's important not to confuse EndType.Polygon with EndType.Joined. EndType.Polygon should be used when offsetting polygons (closed paths). EndType.Joined should be used with polylines (open paths).
  • Offsetting should not be performed on intersecting closed paths, as doing so will almost always produce undesirable results. Intersections must be removed before offsetting, which can be achieved through a Union clipping operation.
  • It is OK to offset self-intersecting open paths (polylines), though the intersecting (overlapping) regions will be flattened in the solution polygon.
  • When offsetting closed paths (polygons), the winding direction of paths in the solution will match that of the paths prior to offsetting. Polygons with hole regions should comply with NonZero filling.
  • When offsetting open paths (polylines), the solutions will always have Positive orientation.
  • Path order following offsetting very likely won't match path order prior to offsetting.
  • While the ClipperOffset class itself won't accept paths with floating point coordinates, the InflatePaths function will accept paths with floating point coordinates.
  • Redundant segments should be removed before offsetting (see simplifyPaths()), and between offsetting operations too. These redundant segments not only slow down offsetting, but they can cause unexpected blemishes in offset solutions.

  • Constructor Details

    • ClipperOffset

      public ClipperOffset(double miterLimit, double arcTolerance, boolean preserveCollinear)
      See Also:

    • ClipperOffset

      public ClipperOffset(double miterLimit, double arcTolerance)
      See Also:

    • ClipperOffset

      public ClipperOffset(double miterLimit)
      See Also:

    • ClipperOffset

      public ClipperOffset()
      Creates a ClipperOffset object, using default parameters.
      See Also:

    • ClipperOffset

      public ClipperOffset(double miterLimit, double arcTolerance, boolean preserveCollinear, boolean reverseSolution)
      Creates a ClipperOffset object, using the supplied parameters.
      Parameters:
      miterLimit - This property sets the maximum distance in multiples of groupDelta that vertices can be offset from their original positions before squaring is applied. (Squaring truncates a miter by 'cutting it off' at 1 × groupDelta distance from the original vertex.)

      The default value for miterLimit is 2 (i.e. twice groupDelta). This is also the smallest MiterLimit that's allowed. If mitering was unrestricted (ie without any squaring), then offsets at very acute angles would generate unacceptably long 'spikes'.

      arcTolerance - Since flattened paths can never perfectly represent arcs (see Trigonometry), this property specifies a maximum acceptable imperfection for rounded curves during offsetting.

      It's important to make arcTolerance a sensible fraction of the offset groupDelta (arc radius). Large tolerances relative to the offset groupDelta will produce poor arc approximations but, just as importantly, very small tolerances will slow offsetting performance without noticeably improving curve quality.

      arcTolerance is only relevant when offsetting with JoinType.Round and / or EndType.Round (see {addPath() and addPaths(). The default arcTolerance is 0.0, which enables automatic scaling (offset radius / 500).

      preserveCollinear - When adjacent edges are collinear in closed path solutions, the common vertex can safely be removed to simplify the solution without altering path shape. However, because some users prefer to retain these common vertices, this feature is optional. Nevertheless, when adjacent edges in solutions are collinear and also create a 'spike' by overlapping, the vertex creating the spike will be removed irrespective of the PreserveCollinear setting. This property is false by default.
      reverseSolution - reverses the solution's orientation

  • Method Details

    • clear

      public final void clear()

    • addPath

      public final void addPath(Path64 path, JoinType joinType, EndType endType)

    • addPaths

      public final void addPaths(Paths64 paths, JoinType joinType, EndType endType)

    • execute

      public final void execute(double delta, Paths64 solution)

    • execute

      public void execute(DeltaCallback64 deltaCallback64, Paths64 solution)

    • execute

      public void execute(double delta, PolyTree64 solutionTree)

    • getArcTolerance

      public final double getArcTolerance()

    • setArcTolerance

      public final void setArcTolerance(double value)

    • getMergeGroups

      public final boolean getMergeGroups()

    • setMergeGroups

      public final void setMergeGroups(boolean value)

    • getMiterLimit

      public final double getMiterLimit()

    • setMiterLimit

      public final void setMiterLimit(double value)

    • getPreserveCollinear

      public final boolean getPreserveCollinear()

    • setPreserveCollinear

      public final void setPreserveCollinear(boolean value)

    • getReverseSolution

      public final boolean getReverseSolution()

    • setReverseSolution

      public final void setReverseSolution(boolean value)

    • setDeltaCallBack64

      public final void setDeltaCallBack64(DeltaCallback64 callback)

    • getDeltaCallBack64

      public final DeltaCallback64 getDeltaCallBack64()