Description
Identify exactly zero-length edges in an implicitly closed polygon coordinate cycle; explicit repeated closure creates a zero closing edge.
Planar geometry operates on two-coordinate Cartesian points and explicit shape boundaries. A closed rectangle includes its edges, while a segment parameter locates a point along a supporting line. Signed cross products, areas and axis gaps preserve orientation or direction information that a magnitude alone would lose.
Identify exactly zero-length edges in an implicitly closed polygon coordinate cycle; explicit repeated closure creates a zero closing edge.
When to use this tool
Use this tool to identify exactly zero-length edges in an implicitly closed polygon coordinate cycle; explicit repeated closure creates a zero closing edge.
How to use the tool and how it works
- Enter points using the input definitions below.
- Run the operation. Resolve malformed-input errors before interpreting the result.
- Read result.edges. Interpret signs, units, ordering and null values using the rules below.
Treat the supplied points as a closed cycle and compare each point exactly with its successor, including the last-to-first edge. Return indexes of edges whose two coordinate components are equal.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| points | Ordered planar [x,y] points. Polygon operations close the cycle implicitly; polyline operations use adjacent pairs only. | Dense list of at most 128 rows of at most 128 finite numbers; the operation’s shape constraints also apply. |
| Output field | Interpretation |
|---|---|
| result | Object containing the fields below. |
| result.edges | Original zero-length edge indexes, including the implicit closing edge where applicable. |
{
"input": {
"points": [
[
0,
0
],
[
1,
0
],
[
1,
0
]
]
},
"output": {
"result": {
"edges": [
1
]
}
}
}Limitations and assumptions
- An explicit repeated first point creates an extra zero closing edge. Empty input returns no edges; a one-point cycle has a zero edge.
- Point components and rectangle bounds are finite within ±1,000,000,000. Rectangles use [minX,minY,maxX,maxY] with ordered inclusive bounds. Floating arithmetic is used without an implicit robustness tolerance.
- Every declared top-level input is required and unknown fields are rejected. Ordinary strings are limited to 8,192 UTF-16 code units and lists to 128 entries, with tighter operation-specific bounds where stated. JSON text has bounded nesting and node counts.
- Numeric outputs must be finite and within the absolute safe-integer magnitude; exact larger integers use decimal text. Source positions are zero-based UTF-16 offsets and span ends are exclusive unless a different convention is explicitly stated.
Alternative or Complementary methods
Choose the boundary and coordinate convention explicitly. Use robust geometric predicates or a topology-aware library when near-coincidence, holes, invalid polygons or geographic coordinates matter.
References
Similar or alternative tools
- Polygon Edge Orientation Table
Report directed polygon edge displacements and radian orientations; zero edges have null direction, and the cycle is implicitly closed.
- Polygon Half Plane Clip
Clip an ordered polygon against the closed half-plane nx*x+ny*y<=maximum; no self-intersection validation or geographic geometry.