How to plot specified semi-circle, rectangle ?
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Hi all
I have 2 points, and need to plot semi-circle, rectangle as folowing picture.
semi-circle need to perpendiculars with slope of 2 points line.
In Case A - simple case which Ay = By. I created code as:
A = [2,2];
B = [5,2];
plot([A(1) B(1)],[A(2) B(2)],'-og');
hold on;
x_centerCircle = A(1);
y_centerCircle = A(2);
r=1; % Radius 1m
theta = linspace(pi/2, 3*pi/2, 100);
xCirc = r * cos(theta) + x_centerCircle;
yCirc = r * sin(theta) + y_centerCircle;
plot(xCirc, yCirc, 'r');
plot([xCirc(1), xCirc(end)], [yCirc(1), yCirc(end)], 'r');
rectangle('Position',[x_centerCircle x_centerCircle-0.075 5 0.15], 'EdgeColor', 'r');
grid on;
xlim([0 8]);
ylim([0 4]);
But when line AB does not parallel with Ox (Case B), becomes more difficult.
Do anyone show me how to plot for all cases?
Thank you so much
采纳的回答
Below is a function that does it, and here are some examples of its usage:
create_semi_rect_patch();%[2 2],[5 2],0.15,1)
axis equal
figure();
create_semi_rect_patch([2 2],[2+sqrt(7.56) 3.2],0.15,1);
axis equal
figure();
create_semi_rect_patch([0 2],[0 10],2,1.5);
axis equal
figure();
create_semi_rect_patch([-2 2],[0 0],1,1.5,4);
axis equal
function p = create_semi_rect_patch(A,B,h,r,Npts_semi)
if ~nargin || isempty(A) % if no A specified, use [2 2]
A = [2 2];
end
if nargin < 2 || isempty(B) % if no B specified, use [5 2]
B = [5 2];
end
if nargin < 3 || isempty(h) % if no h specified, use 0.15
h = 0.15; % (half-height of the rectangle)
end
if nargin < 4 || isempty(r) % if no r specified, use 1
r = 1; % (radius of the semi-circle)
end
if nargin < 5 || isempty(Npts_semi) % if no Npts_semi specified, use 100
Npts_semi = 100; % (number of points along semi-circle)
end
% angle from A to B:
theta = atan2(B(2)-A(2),B(1)-A(1));
% coordinates of the corners of the rectangle:
corner_offset = h*[1;-1]*[cos(theta+pi/2) sin(theta+pi/2)];
rect_points = [A+corner_offset; B+corner_offset];
% coordinates of the points along the semi-circle:
theta_semi = linspace(theta+pi/2,theta+3*pi/2,Npts_semi).';
semi_points = A+r*[cos(theta_semi) sin(theta_semi)];
% create the patch:
p = patch( ...
'XData',[semi_points(:,1); rect_points([2 4 3 1],1)], ...
'YData',[semi_points(:,2); rect_points([2 4 3 1],2)], ...
'FaceColor','flat', ...
'EdgeColor','none', ...
'FaceVertexCData',[1 0 0], ...
'FaceAlpha',0.2);
end
1 个评论
Thank you for your answer.
I had idea about rotation position for each points.
clc;
clear all;
A = [8,1];
B = [5,2];
plot([A(1) B(1)],[A(2) B(2)],'-og');
hold on;
x_centerCircle = A(1);
y_centerCircle = A(2);
r=1; % Radius 1m
theta = linspace(pi/2, 3*pi/2, 100);
xCirc = r * cos(theta) + x_centerCircle;
yCirc = r * sin(theta) + y_centerCircle;
xyCirc = zeros(2, length(xCirc));
for cnt = 1:length(xCirc)
xyCirc(:,cnt) = RotationPoint(A, B, [xCirc(cnt), yCirc(cnt)]);
end
xCirc = xyCirc(1,:);
yCirc = xyCirc(2,:);
plot(xCirc, yCirc, 'r', 'Tag', 'pos_shape');
plot([xCirc(1), xCirc(end)], [yCirc(1), yCirc(end)], 'r', 'Tag', 'pos_shape');
bbox = [A(1) A(2)-0.075 5 0.15];
points = bbox2points(bbox);
rec_points = zeros(2, length(points));
for cnt = 1:length(points)
rec_points(:,cnt) = RotationPoint(A, B, [points(cnt,1), points(cnt,2)]);
end
points2 = horzcat(rec_points(1,:)', rec_points(2,:)');
points2(end+1,:) = points2(1,:);
plot(points2(:,1),points2(:,2), '*-');
grid on;
xlim([-10 10]);
ylim([-10 10]);
function [rotated_Point] = RotationPoint(point1, point2, rotationPointIn)
AB = point2-point1;
theta = atan2(AB(2), AB(1));
Rot_by_theta=[cos(theta) -sin(theta) ; sin(theta) cos(theta)];
AC_ = [rotationPointIn(1) - point1(1); rotationPointIn(2) - point1(2)];
A_ = [point1(1); point1(2)];
rotated_Point = Rot_by_theta * AC_ + A_;
end
It is Ok for me.
But your idea also fantastic. I will consider to use your function.
Thank you so much.
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