LineString

A TypeScript library for handling LineString geometric objects, supporting creation, cloning, transformation, and various geometric operations.

Features

• Create and manage LineString objects
• Support for WKT format parsing
• Geometric transformations: translation, scaling, rotation
• Line simplification and smoothing
• Matrix transformation support
• Coordinate operations

Installation

# Install via npm
npm install linestring

# Or install via yarn
yarn add linestring

Usage Examples

Basic Usage

import { LineString, create, fromWKT, clone } from 'linestring';

// Create a new LineString object
const line = create();

// Create from WKT string
fromWKT(line, "LINESTRING(116.36 39.90, 116.46 39.90, 116.56 39.90)");

// Clone a LineString object
const clonedLine = clone(line);

Geometric Transformations

import { translate, scale, rotate } from 'linestring';

// Translation
translate(line, line, 10, 5); // Translate 10 units on X-axis, 5 units on Y-axis

// Scaling
scale(line, line, [2, 2], [0, 0]); // Scale by 2x on both axes with origin as center

// Rotation
rotate(line, line, Math.PI / 4, [0, 0]); // Rotate 45 degrees around the origin

Line Processing

import { simplify, smooth } from 'linestring';

// Simplify line (using Douglas-Peucker algorithm)
simplify(line, line, 0.01); // Tolerance value of 0.01

// Smooth line (using Catmull-Rom spline algorithm)
smooth(line, line, 0.5, 10); // Tension value 0.5, 10 interpolation points per segment

Matrix Transformation

import { transformMat3 } from 'linestring';

// Transform using a 3x3 matrix
const matrix = new Float32Array([
  1, 0, 0,
  0, 1, 0,
  10, 5, 1  // Translation part
]);

transformMat3(line, line, matrix);

API Documentation

LineString Class

Represents a LineString geometric object.

class LineString {
  type: string;           // Object type, fixed as "LineString"
  coordinates: number[][]; // Coordinate array, each element in [x, y] format
}

Function List

create()

Creates a new empty LineString object.

clone(a: LineString): LineString

Clones a LineString object.

fromWKT(out: LineString, wkt: string): void

Creates a LineString object from a WKT format string.

transformMat3(out: LineString, a: LineString, mat3: Float32Array): LineString

Transforms a LineString object using a 3x3 matrix.

translate(out: LineString, a: LineString, dx: number, dy: number = 0): LineString

Translates a LineString object.

scale(out: LineString, a: LineString, scale: number[], origin: number[] = [0, 0]): LineString

Scales a LineString object.

rotate(out: LineString, a: LineString, rad: number, origin: number[] = [0, 0]): LineString

Rotates a LineString object around a specified point.

simplify(out: LineString, a: LineString, tolerance: number): LineString

Simplifies a LineString object using the Douglas-Peucker algorithm.

smooth(out: LineString, a: LineString, tension: number = 0.5, numOfSegments: number = 10): LineString

Smooths a LineString object using the Catmull-Rom spline algorithm.

Data Format

LineString Structure

{
  "type": "LineString",
  "coordinates": [
    [116.36, 39.90],
    [116.46, 39.90],
    [116.56, 39.90]
  ]
}

WKT Format Support

Supports parsing LINESTRING type WKT format:

LINESTRING(116.36 39.90, 116.46 39.90, 116.56 39.90)

License

MIT

Contributing

Welcome to submit Issues and Pull Requests to improve this library. ```