ellipse

问题 How to test if a point P = [xp,yp] is inside/outside some rotated ellipse given by the centre C=[x,y], a, b, and phi ( angle of rotation)? At this moment I am using the following solution: rotate ellipse and point by the angle -phi and then the common test for a position of the point and "non rotated" ellipse. But there are a lot of tested points (thousands) and I find this solution as slow. Is there any direct and more efficient way to get a position of the rotated ellipse and point? I do

问题 How to test if a point P = [xp,yp] is inside/outside some rotated ellipse given by the centre C=[x,y], a, b, and phi ( angle of rotation)? At this moment I am using the following solution: rotate ellipse and point by the angle -phi and then the common test for a position of the point and "non rotated" ellipse. But there are a lot of tested points (thousands) and I find this solution as slow. Is there any direct and more efficient way to get a position of the rotated ellipse and point? I do

问题 I want that the x-position (=d_in) of my object (the Ellipse) is changed by changing the slider d_in. This is what I got: from numpy import pi, sin import numpy as np import matplotlib.pyplot as plt from matplotlib.widgets import Slider, Button, RadioButtons from matplotlib.patches import Ellipse from scipy.optimize import fsolve import pylab axis_color = 'lightgoldenrodyellow' #variable d_in=80 fig = plt.figure(figsize=(12,6)) ax = fig.add_subplot(111) fig.subplots_adjust(left=0.25, bottom=0

问题 I have a UIView with bounds (w, h) and I am trying to calculate angles and point on a ellipse which is centred at view's mid point i.e. centre is (w * 0.5, h * 0.5). I continuously change the size of view and ellipse so following values are from console for a instance of values. For this instance, (w, h) = (150.000000, 300.799988) and radii are (rx, ry) = (52.500000, 105.279999) Now, I try to find angle of point P1(x,y) (30.784275, 93.637390) on this ellipse using following code: CGFloat

问题 I have a UIView with bounds (w, h) and I am trying to calculate angles and point on a ellipse which is centred at view's mid point i.e. centre is (w * 0.5, h * 0.5). I continuously change the size of view and ellipse so following values are from console for a instance of values. For this instance, (w, h) = (150.000000, 300.799988) and radii are (rx, ry) = (52.500000, 105.279999) Now, I try to find angle of point P1(x,y) (30.784275, 93.637390) on this ellipse using following code: CGFloat

问题 This method for drawing ellipses appears to be clean and elegant: http://www.williammalone.com/briefs/how-to-draw-ellipse-html5-canvas/ However, in testing it, I found that the resulting ellipses were stretched. Setting width and height equal, I got ellipses that were about 20% taller than wide. Here's the result with width = height = 50 : To make sure that the problem was with the method itself, I tried changing the algorithm so that all the points used for the Bezier curves were rotated 90

问题 I am trying to draw a letter "O" with Python turtle graphics. To cue the drawing of the "O", the function for it is invoked with a key press. Here is what I have so far: def draw_O(): # Draw an O penup() forward(letter_height/4) pendown() forward(letter_width/2) circle(letter_height/4, 90) forward(letter_height/2) circle(letter_height/4, 90) forward(letter_width/2) circle(letter_height/4, 90) forward(letter_height/2) circle(letter_height/4, 90) forward(letter_width/2) penup() forward(space

问题 We have Rectangle fillings , circle and ellipse filling in opencv, but can anyone say how to fill a triangle in an image using opencv ,python. 回答1: The simplest solution of filling a triangle shape is using draw contour function in OpenCV. Assuming we know the three points of the triangle as "pt1", "pt2" and "pt3": import cv2 import numpy as np image = np.ones((300, 300, 3), np.uint8) * 255 pt1 = (150, 100) pt2 = (100, 200) pt3 = (200, 200) cv2.circle(image, pt1, 2, (0,0,255), -1) cv2.circle

问题 While working on SVG implementation for Internet Explorer to be based on its own VML format I came to a problem of translation of an SVG elliptical arc to an VML elliptical arc. In VML an arc is given by: two angles for two points on ellipse and lengths of radiuses, In SVG an arc is given by: two pairs of coordinates for two points on ellipse and sizes of ellipse boundary box So, the question is: How to express angles of two points on ellipse to two pairs of their coordinates. An intermediate

问题 So as the title states, I would want to move the ellipse on mouse drag. I have declared ellipses first and drew them through ArrayLists (since I have 8 ellipses which carry different color information. Four are white and the other are red). I tried doing what I did for the rectangles: public void mousePressed(MouseEvent e) { x = e.getX(); y = e.getY(); } public void mouseDragged(MouseEvent e) { if(e.getSource()==MainPane) { int dx = e.getX() - x; int dy = e.getY() - y; Point p = getLocation()