https://github.com/scivision/lineclipping-python-fortran

Line clipping in clean, simple, modern Fortran and Python
https://github.com/scivision/lineclipping-python-fortran

coarray-fortran cohen-sutherland computer-vision line-clipping

Last synced: 14 days ago
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Line clipping in clean, simple, modern Fortran and Python

• Host: GitHub
• URL: https://github.com/scivision/lineclipping-python-fortran
• Owner: scivision
• License: mit
• Created: 2018-02-21T22:23:13.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2021-05-10T02:14:55.000Z (over 3 years ago)
• Last Synced: 2024-09-21T13:57:17.251Z (about 2 months ago)
• Topics: coarray-fortran, cohen-sutherland, computer-vision, line-clipping
• Language: Fortran
• Size: 44.9 KB
• Stars: 10
• Watchers: 3
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# Line clipping

[![Actions Status](https://github.com/scivision/lineclipping-python-fortran/workflows/ci_python/badge.svg)](https://github.com/scivision/lineclipping-python-fortran/actions)

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`lineclipping.f90` Cohen-Sutherland line clipping algorithm for

massively parallel coarray modern Fortran. Input scalars or arrays,

output intersections or `NaN` if no intersection.

`lineClipping.py` Cohen-Sutherland line clipping algorithm for Python.

Input scalars, output intersection length, or `None` if no intersection.

Julia line clipping is at https://github.com/scivision/lineclipping-julia

## Install

To install the latest release:

```sh

pip install pylineclip

```

### Fortran

If you want to use the Fortran Cohen-Sutherland line clipping modules

directly (optional):

```sh

meson build

meson test -C build

```

## Usage

The main difference with textbook implementations is that I return a

sentinel value (NaN, None, nothing) if there's no intersection of line

with box.

### Python

```python

import pylineclip.lineclipping as lc

x3,y3,x4,y4 = lc.cohensutherland((xmin, ymax, xmax, ymin, x1, y1, x2, y2)

```

If no intersection, `(None, None, None, None)` is returned.

### Fortran

lineclipping.f90 has two subroutines.

Pick Ccohensutherland if you're calling from C/C++/Python, which cannot tolerate assummed-shape arrays.

It's a slim wrapper to cohensutherland which is elemental (can handle scalar or any rank array).

Fortran programs will simply use

```fortran

use lineclipping

call cohensutherland(xmin,ymax,xmax,ymin,x1,y1,x2,y2)

```

The arguments are:

```sh

INPUTS

------

xmin,ymax,xmax,ymin:  upper left and lower right corners of box (pixel coordinates)

INOUT

-----

x1,y1,x2,y2:

in - endpoints of line

out - intersection points with box. If no intersection, all NaN

```