The easiest way to do it is by using masks. Create a black and white mask with any shape you want. And use putalpha to put that shape as an alpha layer: from PIL import Image, ImageOps mask = Image.open(‘mask.png’).convert(‘L’) im = Image.open(‘image.png’) output = ImageOps.fit(im, mask.size, centering=(0.5, 0.5)) output.putalpha(mask) output.save(‘output.png’) Here is the mask … Read more
Check if the cross product of (b-a) and (c-a) is 0, as tells Darius Bacon, tells you if the points a, b and c are aligned. But, as you want to know if c is between a and b, you also have to check that the dot product of (b-a) and (c-a) is positive and … Read more
If we define dx = x2 – x1 and dy = y2 – y1, then the normals are (-dy, dx) and (dy, -dx). Note that no division is required, and so you’re not risking dividing by zero.
I was curious and planned to do stuff needed for this in GLSL math style anyway. So here a different approach. Let consider this definition of your cone: create a set of basic geometry primitives You need to support points,lines,triangles,convex triangulated mesh,spherical sector (cone). implement inside test between point and triangle,mesh,cone for triangle the results … Read more
How is the rectangle represented? Three points? Four points? Point, sides and angle? Two points and a side? Something else? Without knowing that, any attempts to answer your question will have only purely academic value. In any case, for any convex polygon (including rectangle) the test is very simple: check each edge of the polygon, … Read more
If I understand this correctly, you’re trying to infer (but not measure) the radius r0 of the tube from measurements for y and a. Applying the usual error propagation to your formula for r0, one obtains (an estimate for) the error of the resulting r0. In the limit of small angles (applicable here, since a(t) … Read more
You can make things a lot easier than the Gift-Wrapping Algorithm… that’s a good answer when you have a set of points w/o any particular boundary and need to find the convex hull. In contrast, consider the case where the polygon is not self-intersecting, and it consists of a set of points in a list … Read more
Compute unit vectors from the angles and take the angle of their average.
Points on a circle may be specified as a function of the angle θ: x = a + r cos(θ) y = b + r sin(θ) Here, increments of 2π/8 are shown. Addendum: As suggested in a comment by @Christoffer Hammarström, this revised example reduces the number of magic numbers in the original. The desired … Read more
The point A is always outside of the rectangle and the point B is always at the center of the rectangle Assuming the rectangle is axis-aligned, this makes things pretty simple: The slope of the line is s = (Ay – By)/(Ax – Bx). If -h/2 <= s * w/2 <= h/2 then the line … Read more