https://github.com/dubniczky/convex-hull

Optimizing a convex hull using trigonometric elimination on a web environment
https://github.com/dubniczky/convex-hull

algorithm javascript optimization p5js web

Last synced: 8 months ago
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Optimizing a convex hull using trigonometric elimination on a web environment

• Host: GitHub
• URL: https://github.com/dubniczky/convex-hull
• Owner: dubniczky
• License: mit
• Created: 2022-08-03T16:21:30.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2022-08-03T16:37:12.000Z (over 3 years ago)
• Last Synced: 2025-02-06T19:49:26.147Z (10 months ago)
• Topics: algorithm, javascript, optimization, p5js, web
• Language: JavaScript
• Homepage:
• Size: 148 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Trigonometric Convex Hull

Optimizing a convex hull using trigonometric elimination.

## Support ❤️

If you find the project useful, please consider supporting, or contributing.

[!["Buy Me A Coffee"](https://www.buymeacoffee.com/assets/img/custom_images/orange_img.png)](https://www.buymeacoffee.com/dubniczky)

## Live Demo

https://dubniczky.github.io/Convex-Hull/

## Algorithm details

1. Calculate center point from average positions.

2. Sort points based on distance from center.

3. Eliminate center points using triangle intersection.

4. Sort remaining points based on theta angle from center.

5. Connect remaining points in sequence.

## Triangle intersection code sample

```javascript

let edges = []

for (let i = points.length - 1; i >= 0; i--) {

    let intersect = false

    for (let j = 0; !intersect && j < points.length - 1; j++) {

        if (j == i) {

            continue

        }

        for (let k = j + 1; !intersect && k < points.length; k++) {

            if (k == i) {

                continue

            }

            let a = points[i]

            let b = points[j]

            let c = points[k]

            let d = center

            let d1 = (a.pos.x - c.pos.x) * (b.pos.y - c.pos.y) - (b.pos.x - c.pos.x) * (a.pos.y - c.pos.y)

            let d2 = (a.pos.x - d.pos.x) * (b.pos.y - d.pos.y) - (b.pos.x - d.pos.x) * (a.pos.y - d.pos.y)

            let d3 = (a.pos.x - d.pos.x) * (c.pos.y - d.pos.y) - (c.pos.x - d.pos.x) * (a.pos.y - d.pos.y)

            let neg = (d1 < 0) || (d2 < 0) || (d3 < 0)

            let pos = (d1 > 0) || (d2 > 0) || (d3 > 0)

            if (!(neg && pos)) {

                intersect = true

            }

        }

    }

    if (!intersect) {

        edges.push(i)

    }

}

```

## Usage

Run the `./deploy.sh` script.

Host `./public` folder on a static file server or open `./public/index.html` locally in your browser.