https://github.com/cuixing158/pointpolygontest

determine points are inside, on or outside a polygon/contour or calculate signed distance between points and the nearest contour edge.
https://github.com/cuixing158/pointpolygontest

algorithm c computer-geometry

Last synced: 29 days ago
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determine points are inside, on or outside a polygon/contour or calculate signed distance between points and the nearest contour edge.

• Host: GitHub
• URL: https://github.com/cuixing158/pointpolygontest
• Owner: cuixing158
• Created: 2022-10-23T02:36:46.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2025-02-02T04:08:52.000Z (4 months ago)
• Last Synced: 2025-04-06T20:47:42.491Z (about 2 months ago)
• Topics: algorithm, c, computer-geometry
• Language: C
• Homepage:
• Size: 107 KB
• Stars: 16
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
[![View pointPolygonTest on File Exchange](https://www.mathworks.com/matlabcentral/images/matlab-file-exchange.svg)](https://ww2.mathworks.cn/matlabcentral/fileexchange/119418-pointpolygontest) 

[![Open in MATLAB Online](https://www.mathworks.com/images/responsive/global/open-in-matlab-online.svg)](https://matlab.mathworks.com/open/github/v1?repo=cuixing158/pointPolygonTest&file=demo.m)

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# Points In Polygon Test

This function [`inpolygon2`](./inpolygon2.m) is an enhancement of matlab's built-in function [`inpolygon`](https://www.mathworks.cn/help/matlab/ref/inpolygon.html), which supports the calculation of the distances.Support C/C++ code generation.

:eyes:[View the example](https://viewer.mathworks.com/?viewer=plain_code&url=https%3A%2F%2Fww2.mathworks.cn%2Fmatlabcentral%2Fmlc-downloads%2Fdownloads%2F86ed6463-8f26-4463-acc2-d739927612b1%2F53ec9495-8b54-49be-8855-fce595cdfa4e%2Ffiles%2Fdemo.m&embed=web) 

:arrow_forward:[Run the example](https://matlab.mathworks.com/open/github/v1?repo=cuixing158/pointPolygonTest&file=demo.m)

## Example

```matlab

%% data, is same as https://www.mathworks.cn/help/matlab/ref/inpolygon.html fisrst Example

L = linspace(0,2*pi,6);

xv = cos(L)';

yv = sin(L)';

rng default

xq = randn(250,1);

yq = randn(250,1);

%% use inpolygon2 function determine points whether inside polygon 

points = [xq,yq];

dists = inpolygon2([xv,yv],points);

figure;hold on

plot(xv,yv) % polygon

plot(xq(dists==1),yq(dists==1),'r+') % points inside

plot(xq(dists==-1),yq(dists==-1),'bo') % points outside

axis equal;

title("points in polygon")

```

![img](images/a.png)

```matlab

%% Distance Rating Heat Map

xy=-2:.02:2;

[x,y] = meshgrid(xy);

points = [x(:),y(:)];

dists2 = inpolygon2([xv,yv],points,true);

dists2 = reshape(dists2,size(x));

figure;hold on;

xydata = [xy(1),xy(end)];

imagesc(xydata,xydata,dists2)

plot(xv,yv,'w-','LineWidth',2)

colormap('jet');

colorbar

axis equal off

title("signed distance hot map")

```

![img](images/b.png)