how to fill a specific region with color if that's region contain my target point?

hy guys.

I would like to fill a specific region automatically with the color red in my plot, if that's region contains my target point.

Any idea how to do that's ?

Thank you in advance

my code:

clear all

clc

x = [1 3 4 3 1 0 1];

y = [0 0 2 4 4 2 0];

plot(x,y,'k')

hold on

plot(x+2,y,'k')

plot(x,y+2,'k')

x_target=3;

y_target=3;

plot(x_target,y_target,'or');

Answer 1

[Image Analyst]

Use polyshape:

x = [1 3 4 3 1 0 1];
y = [0 0 2 4 4 2 0];
plot(x,y,'k')
hold on
plot(x+2,y,'k')
plot(x,y+2,'k')
x_target=3;
y_target=3;
plot(x_target,y_target,'or');
% Generate polyshapes
p1 = polyshape(x, y);
p2 = polyshape(x+2, y);
p3 = polyshape(x, y+2);
% Find overlap
p = p1.intersect(p2);
p = p.intersect(p3);
plot(p);

[Rabih Sokhen]

hy there,

Thank you for helping me.

I have changed the value of my x_target from 3 to 4, and I have launched the code, but the code didn't fill the region that's contained the red dot.

How can I make sure that's the region that's containe the red dots get filled?

thank you in advance

[Image Analyst]

It's more complicated. You have to use inpolygon to check if the point is inside or not. Once you've found out which polygon it's inside, you have to subtract or add in the other polygons depending if they contain the point or not. Here's a start

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format short g;
format compact;
fontSize = 22;
markerSize = 20;
x = [1 3 4 3 1 0 1];
y = [0 0 2 4 4 2 0];
x2 = x+2;
y2 = y + 2;
plot(x, y, 'k-', 'LineWidth', 2)
hold on
plot(x2, y, 'b-', 'LineWidth', 2)
darkGreen = [0, 0.5, 0];
plot(x, y2, '-', 'Color', darkGreen, 'LineWidth', 2)
x_target = 4.5;
y_target = 2.5;
plot(x_target,y_target,'r.', 'MarkerSize', 30);
grid on;
legend('p1', 'p2', 'p3', 'target point');
% Generate polyshapes
p1 = polyshape(x, y);
p2 = polyshape(x+2, y);
p3 = polyshape(x, y+2);

% Find which polygon contains the point.
checkedThisPolygon = [false, false, false];
itsInside = inpolygon(x_target, y_target, x, y)
checkedThisPolygon(1) = true;
if itsInside
    p = p1;
else
    % It's not in polygon 1.  Check to see if it's in polygon #2.
    itsInside = inpolygon(x_target, y_target, x2, y);
    checkedThisPolygon(2) = true;
    if itsInside
        p = p2;
    else
        % It's not in polygon 2.  Check to see if it's in polygon #3.
        itsInside = inpolygon(x_target, y_target, x, y2);
        checkedThisPolygon(3) = true;
        if itsInside
            p = p3;
        end
    end
end
% p = p.intersect(p3);
plot(p);

It'll take more work to finish than I have time to donate to you, so good luck.

[Rabih Sokhen]

thank you fo your help