Module engine_fns 

Engine free functions - standalone utility functions for the sweep-line algorithm

Direct port from clipper.engine.cpp Copyright (c) Angus Johnson 2010-2025

Functions

area_outpt

Calculate area of an OutPt circular list Direct port from clipper.engine.cpp line 366

area_triangle

Calculate area of a triangle formed by three points Direct port from clipper.engine.cpp line 380

build_path64_from_outpt

Build a Path64 from OutPt circular list Direct port from clipper.engine.cpp BuildPath64 (line 2891)

build_path_d_from_outpt

Build a PathD from OutPt circular list Direct port from clipper.engine.cpp BuildPathD (line 3055)

edges_adjacent_in_ael

Check if intersect node edges are adjacent in AEL Direct port from clipper.engine.cpp EdgesAdjacentInAEL (line 468)

extract_from_sel

Extract an active from the SEL (sorted edge list) Direct port from clipper.engine.cpp ExtractFromSEL

fix_outrec_pts

Fix all OutPt outrec references in an OutRec Direct port from clipper.engine.cpp FixOutRecPts (line 2158)

get_clean_path

Build a Path64 from an OutRec Direct port from clipper.engine.cpp GetCleanPath equivalent

get_curr_y_maxima_vertex

Get current Y maxima vertex for closed paths Direct port from clipper.engine.cpp line 243

get_curr_y_maxima_vertex_open

Get current Y maxima vertex for open paths Direct port from clipper.engine.cpp line 226

get_dx

Calculate slope dx for an edge defined by two points Direct port from clipper.engine.cpp line 116

get_last_op

Get the last output point for a hot edge Direct port from clipper.engine.cpp GetLastOp (line 2496)

get_maxima_pair

Get the maxima pair for an active edge Direct port from clipper.engine.cpp line 254

get_poly_type

Get the polytype of an active edge Direct port from clipper.engine.cpp line 162

get_real_outrec

Get the real (non-disposed) OutRec by following owner chain Direct port from clipper.engine.cpp GetRealOutRec (line 412)

insert1_before2_in_sel

Insert tmp before left in SEL Direct port from clipper.engine.cpp Insert1Before2InSEL

intersect_list_sort

Sort comparator for IntersectNodes Direct port from clipper.engine.cpp line 322

is_heading_left_horz

Check if a horizontal edge is heading left Direct port from clipper.engine.cpp line 149

is_heading_right_horz

Check if a horizontal edge is heading right Direct port from clipper.engine.cpp line 143

is_horizontal_active

Check if an active edge is horizontal Direct port from clipper.engine.cpp line 137

is_hot_edge

Check if an active edge is “hot” (has an output record) Direct port from clipper.engine.cpp line 67

is_invalid_path

Check if an OutPt path is invalid (single point or None) Direct port from clipper.engine.cpp line 105

is_joined

Check if an edge is joined Direct port from clipper.engine.cpp IsJoined (line 473)

is_maxima_active

Check if an active edge is at a local maximum Direct port from clipper.engine.cpp line 221

is_maxima_vertex

Check if a vertex is a local maximum Direct port from clipper.engine.cpp line 215

is_odd

Check if a value is odd Direct port from clipper.engine.cpp line 61

is_open_active

Check if an active edge is part of an open path Direct port from clipper.engine.cpp line 73

is_open_end_active

Check if an active edge’s vertex_top is an open end Direct port from clipper.engine.cpp line 87

is_open_end_vertex

Check if a vertex is an open end Direct port from clipper.engine.cpp line 79

is_same_poly_type

Check if two active edges are the same polytype Direct port from clipper.engine.cpp line 167

is_valid_ael_order

Check if the AEL ordering is valid between two active edges Direct port from clipper.engine.cpp IsValidAelOrder (line 1119)

is_valid_closed_path

Check if a closed path is valid Direct port from clipper.engine.cpp IsValidClosedPath (line 449)

is_valid_owner

Check if an owner is valid (not circular) Direct port from clipper.engine.cpp IsValidOwner (line 418)

is_very_small_triangle

Check if an OutPt triangle is very small Direct port from clipper.engine.cpp IsVerySmallTriangle (line 441)

move_splits

Move splits from one OutRec to another Direct port from clipper.engine.cpp MoveSplits (line 2269)

next_vertex

Get next vertex for an active edge (depends on winding direction) Direct port from clipper.engine.cpp line 177

outrec_is_ascending

Check if the hot edge is ascending (front edge of its outrec) Direct port from clipper.engine.cpp OutrecIsAscending (line 455)

path2_contains_path1

Check if path1 is contained within path2 using Path64 vectors Direct port from clipper.h line 717 - template Path2ContainsPath1 precondition: paths must not intersect, except for transient micro intersections

path2_contains_path1_outpt

Check if path1 (as OutPt list) is contained within path2 (as OutPt list) Direct port from clipper.engine.cpp Path2ContainsPath1 (line 576)

point_count

Count points in an OutPt circular list Direct port from clipper.engine.cpp line 266

point_in_op_polygon

Point in polygon test for OutPt-based polygons Direct port from clipper.engine.cpp PointInOpPolygon (line 488)

prev_prev_vertex

Get the vertex two steps back (useful for alternate edge top) Direct port from clipper.engine.cpp line 187

pts_really_close

Check if two points are really close (within 2 units) Direct port from clipper.engine.cpp PtsReallyClose (line 436)

reverse_out_pts

Reverse the direction of an OutPt circular list Direct port from clipper.engine.cpp line 388

set_dx

Set dx for an active edge from its bot/top points Direct port from clipper.engine.cpp line 172

set_owner

Set the owner of an OutRec Direct port from clipper.engine.cpp SetOwner (line 478)

swap_front_back_sides

Swap front and back sides of an OutRec Direct port from clipper.engine.cpp SwapFrontBackSides (line 460)

top_x

Get the x coordinate of an active edge at a given y Direct port from clipper.engine.cpp line 127

uncouple_outrec

Uncouple an OutRec from its edges Direct port from clipper.engine.cpp UncoupleOutRec (line 425)

update_outrec_owner

Update all OutPt outrec references in an OutRec Direct port from clipper.engine.cpp UpdateOutrecOwner (line 1684)