quickhull

README

quickhull-go

A 3D Quickhull implementation in Go.

Big thanks to @akuukka for their public domain C++ implementation which was used as a reference.

This is different from Google's S2 Geometry implementation because it works in ℝ³ instead of S².

Go Get

go get -u github.com/markus-wa/quickhull-go/v2

Example

Example with a simple, planar point-cloud.

package main

import (
	"fmt"

	r3 "github.com/golang/geo/r3"
	quickhull "github.com/markus-wa/quickhull-go/v2"
)

func main() {
	pointCloud := []r3.Vector{
		{X: 1, Y: 2, Z: 1},
		{X: 4, Y: 7, Z: 1},
		{X: 7, Y: 2, Z: 1},
		{X: 4, Y: 4, Z: 1}, // This point is inside the hull
	}

	hull := new(QuickHull).ConvexHull(pointCloud, true, false, 0)

	fmt.Println(hull.Vertices) // does not contain (4,4,1)
	fmt.Println(hull.Triangles()) // triangles that make up the convex hull - [][3]r3.Vector, where each vector is a corner of the triangle
}

License

This project is licensed under the MIT license.

Documentation

Index

• type ConvexHull
  • func (hull ConvexHull) Triangles() [][3]r3.Vector
• type Face
• type HalfEdge
• type HalfEdgeMesh
• type QuickHull
  • func (qh *QuickHull) ConvexHull(pointCloud []r3.Vector, ccw bool, useOriginalIndices bool, epsilon float64) ConvexHull
  • func (qh *QuickHull) ConvexHullAsMesh(pointCloud []r3.Vector, epsilon float64) HalfEdgeMesh

Types

type ConvexHull

type ConvexHull struct {
	Vertices []r3.Vector
	Indices  []int
	// contains filtered or unexported fields
}

func (ConvexHull) Triangles

func (hull ConvexHull) Triangles() [][3]r3.Vector

type Face

type Face struct {
	HalfEdge int // Index of a bounding HalfEdge
}

Face of a half edge. See: https://www.openmesh.org/media/Documentations/OpenMesh-6.3-Documentation/a00010.html

type HalfEdge

type HalfEdge struct {
	EndVertex int // Index of end vertex
	Opp       int // Index of opposite HalfEdge
	Face      int // Index of Face it belongs to
	Next      int // Index of next HalfEdge
}

HalfEdge is a half edge. See: https://www.openmesh.org/media/Documentations/OpenMesh-6.3-Documentation/a00010.html

type HalfEdgeMesh

type HalfEdgeMesh struct {
	Vertices  []r3.Vector
	Faces     []Face
	HalfEdges []HalfEdge
}

HalfEdgeMesh is a mesh consisting of half edges. See: https://www.openmesh.org/media/Documentations/OpenMesh-6.3-Documentation/a00010.html

type QuickHull

type QuickHull struct {
	// contains filtered or unexported fields
}

QuickHull can be used to calculate the convex hull of a point cloud. See: https://en.wikipedia.org/wiki/Quickhull

func (*QuickHull) ConvexHull

func (qh *QuickHull) ConvexHull(pointCloud []r3.Vector, ccw bool, useOriginalIndices bool, epsilon float64) ConvexHull

ConvexHull calculates the convex hull of the given point cloud using the Quickhull algorithm. If epsilon is <= 0 a default value will be used.

func (*QuickHull) ConvexHullAsMesh

func (qh *QuickHull) ConvexHullAsMesh(pointCloud []r3.Vector, epsilon float64) HalfEdgeMesh

ConvexHull calculates the convex hull of the given point cloud using the Quickhull algorithm and returns it as a HalfEdgeMesh. If epsilon is <= 0 a default value will be used.