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https://github.com/ricmoo/gmclipper
An Objective-C wrapper for the Clipper polygon clipping and offsetting library.
https://github.com/ricmoo/gmclipper
objective-c polygon-clipping-algorithm
Last synced: 4 months ago
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An Objective-C wrapper for the Clipper polygon clipping and offsetting library.
- Host: GitHub
- URL: https://github.com/ricmoo/gmclipper
- Owner: ricmoo
- License: other
- Created: 2014-12-03T09:51:08.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2014-12-03T09:52:23.000Z (about 10 years ago)
- Last Synced: 2024-10-04T18:56:37.539Z (4 months ago)
- Topics: objective-c, polygon-clipping-algorithm
- Language: C++
- Size: 152 KB
- Stars: 7
- Watchers: 1
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# GMClipper
This is still a complete **work in progress**. I have barely tested it yet, just placing it in github for safe keeping. It's also my first foray into creating a cocoapod. So, you probably really shouldn't try using it yet. More and better documentation will come.
## Features
- Perform boolean (union, intersection, difference, xor) operations on sets of polygons.
- Enlarge or shrink polygons
- Simplify and clean-up polygons
- Fast and simple library
## Adding to Your Project
To use this library, simply copy the files in Pod/Classes into your project, and everything should *just work*. (CocoaPods coming soon)
## API
### Clipping
Clipping allows you to take one set of polygons (the subject) and clip it against another set of polygons (the clipping region).
Examples:
- to only display the complete shapes and parts of complex shapes within a viewport of a larger canvas
- to detect if an item in an island game is actually completely on a set of islands
- to perform general boolean operators on a series of overlapping shapes, like Adobe Illustrator's Path Finder
To clip, simple define your shape(s) and clip:
```objc
#import "GMClipper.h"
// Create a subject polygon
GMPolygon *subject = [GMPolygon polygon];
[subject addPointX:0 y:0];
[subject addPointX:100 y:100];
[subject addPointX:100 y:0];
// Create a clipping polygon (50x50 rectangle)
GMPolygon *clipping = [GMPolygon polygon];
[clipping addPointX:0 y:0];
[clipping addPointX:0 y:50];
[clipping addPointX:50 y:50];
[clipping addPointX:50 y:0];
// Prepare the subject with the clipping polygon for clipping
GMClipper *clipper = [GMClipper clipper];
[clipper addSubjectPolygon:subject];
[clipper addClippingPolygon:clipping];
// Compute the new polygon(s)
NSArray *result = [clipper executeClipType:ClipTypeIntersection];
NSLog(@"Result: %@", result);
```
### Offsetting
Offsetting allows you to grow or shrink a polygon.
Examples:
- to add a border around a complicated shape
- to compute a polygon's stroke's region, you could subtract a shrunk polygon from its enlarged polygon
To enlarge a shape, use a positive distance, to shrink it, use a negative distance.
```objc
#import "GMClipperOffset"
// Create a triangle
GMPolygon *triangle = [GMPolygon polygon];
[triangle addPointX:0 y:0];
[triangle addPointX:100 y:100];
[triangle addPointX:100 y:0];
// Prepare the triangle for enlarging (or shrinking)
GMClipperOffset *clipperOffset = [GMClipperOffset clipperOffset];
[clipperOffset addPolygon:triangle joinType:JoinTypeSquare endType:EndTypeClosedPolygon];
// Compute the triangle enlarged by 10 points
NSArray *result = [clipperOffset executeDelta:10];
NSLog(@"Result: %@", result);
```
## FAQ
### License?
GMClipper is available under the "Boost Software License". Basically:
- if you distribute *source*, include license
- if you distribute *compiled code*, **no need**
I usually release things under the MIT License, however, I am wrapping an existing library, so this keeps things simple.
See the LICENSE file for more info.
### Have a question?
E-mail me at [email protected].