https://github.com/owengombas/hand-drawing-swift-metal

✏️ Drawing engine with Swift and Metal (GPU)
https://github.com/owengombas/hand-drawing-swift-metal

cpu draw drawing gpu metal optimized performance swift

Last synced: 7 months ago
JSON representation

✏️ Drawing engine with Swift and Metal (GPU)

• Host: GitHub
• URL: https://github.com/owengombas/hand-drawing-swift-metal
• Owner: owengombas
• License: mit
• Created: 2019-08-03T15:57:21.000Z (about 6 years ago)
• Default Branch: master
• Last Pushed: 2019-08-08T22:22:42.000Z (about 6 years ago)
• Last Synced: 2024-05-19T11:08:05.375Z (over 1 year ago)
• Topics: cpu, draw, drawing, gpu, metal, optimized, performance, swift
• Language: Swift
• Homepage:
• Size: 63.5 KB
• Stars: 79
• Watchers: 8
• Forks: 14
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

Awesome Lists containing this project

README

          
# Draw on an iOS device using Metal ✏️

## TODOs and WIP tasks ✅

Look at the the project board [here](https://github.com/OwenCalvin/hand-drawing-swift-metal/projects/1)

## How does it works 📟 ?

### Line system

A line is composed of a multitude of interconnected triangles, they are generated from **"key point"** which are **the points having as coordinates the places where you have slipped your finger/pen and handled by your device**. Several linked triangles can form a trapeze which allows to manage the force communicated with the apple pen in order to vary the width of the line on the same line.

![](https://github.com/eldade/ios_metal_bezier_renderer/blob/master/Wireframe_Screenshot.png)

*Image from [ios_metal_bezier_renderer](https://github.com/eldade/ios_metal_bezier_renderer)*  

![](https://i.imgur.com/8t2qGRj.png)

*From XCode debugger*

### Interpolation

I use the Catmull Rom interpolation, it generates points between each **key points**   

*With interpolation:*  

![](https://i.imgur.com/dw193ag.jpg)

*Without interpolation (only the **key points**):*  

![](https://i.imgur.com/UTst8CB.jpg)  

## See also

- [ios_metal_bezier_renderer](https://github.com/eldade/ios_metal_bezier_renderer)

- [Catmull–Rom spline interpolation](https://en.wikipedia.org/wiki/Centripetal_Catmull–Rom_spline)

- [Ramer-Douglas-Peucker algorithm](https://en.m.wikipedia.org/wiki/Ramer–Douglas–Peucker_algorithm)

- [Helpful StackOverflow question](https://stackoverflow.com/questions/42889699/smooth-drawing-with-apple-pencil)