Some geometry with Paint: 0. You have a corner: 1. You know the coordinates of corner points, let it be P1, P2 and P: 2. Now you can get vectors from points and angle between vectors: angle = atan(PY – P1Y, PX – P1X) – atan(PY – P2Y, PX – P2X) 3. Get the length … Read more
Arash Partow’s FastGEO library contains implementations of many interesting algorithms in computational geometry. Polygon intersection is one of them. It’s written in Pascal, but it’s only implementing math so it’s pretty readable. Note that you will certainly need to preprocess your edges a little, to get them into clockwise or counterclockwise order. ETA: But really, … Read more
Use the Ray Casting algorithm for checking if a point (marker) lies inside of a polygon: function isMarkerInsidePolygon(marker, poly) { var polyPoints = poly.getLatLngs(); var x = marker.getLatLng().lat, y = marker.getLatLng().lng; var inside = false; for (var i = 0, j = polyPoints.length – 1; i < polyPoints.length; j = i++) { var xi = … Read more
GL_POLYGON is only for convex polygons: GL_POLYGON: Draws a single, convex polygon. Vertices 1 through N define this polygon. For concave polygons you have at least two options: Triangulate the polygon and use GL_TRIANGLES. Use the stencil buffer trick.
Get the indices where the y value of two consecutive time steps have different sign. Use linear interpolation between these points to generate new x values where y is zero. First, a smaller example to make it easier to get a feeling for the linear interpolation and which points are added to the original data: … Read more
You can do this simply with gContains(…) in the rgeos package. gContains(sp1,sp2) returns a logical depending on whether sp2 is contained within sp1. The only nuance is that sp2 has to be a SpatialPoints object, and it has to have the same projection as sp1. To do that, you would do something like this: point … Read more
this task is extremly hard to do. need to have the boundary polygon you want to fill with spiral I think you have it already create new smaller polygon by shifting all lines inwards by the step. It is similar to create stroke line around polygon. Step is the screw width so at start of … Read more
I’m not exactly sure what matlab does, but you can draw a polygon using matplotlib.patches.Polygon. Adapted from an example in the docs: import numpy as np import matplotlib.pyplot as plt import matplotlib from matplotlib.patches import Polygon from matplotlib.collections import PatchCollection fig, ax = plt.subplots() patches = [] num_polygons = 5 num_sides = 5 for i … Read more
In general, you can simply compute the threshold using cv::threshold, and then copy the src image on dst using the inverted mask. // Apply cv::threshold on all image thresh = cv::threshold(src, dst, thresh, maxval, type); // Copy original image on inverted mask src.copyTo(dst, ~mask); With THRESH_OTSU, however, you also need to compute the threshold value … Read more
Perform line intersection tests for each pair of lines, one from each polygon. If no pairs of lines intersect and one of the line end-points of polygon A is inside polygon B, then A is entirely inside B. The above works for any type of polygon. If the polygons are convex, you can skip the … Read more