Question regarding impoly restraint to move about a specified path

Lets say I have an implicit equation in x and y f(x,y)=x^2 + y^2 -5*x +12*y +24 which is an example. I construct an impoly with three or n number of vertices over the curve.My question is how can I restrict the movement of vertices of impoly to be restricted to follow the path of the curve.

[darova]

PLease attach some example or something

[Saikat Banerjee]

I have already attached example. Read question carefully. Let us say we construct a circle through fimplicit(x^2 + y^2 -5*x +12*y +24). After that we construct a traingle with three vertices using impoly. Now the vertices of the triangle will only move along the Circle. Restrain the movement of vertices using impoly along the circle. It will not go inside the circle or can come out of the circle. It will only move on the curve of the Circle

Answer 1

[darova]

Use setPositionConstraintFcn function

function main
clc,clear

x = 0:.05:10;
y = sin(x);
plot(x,y,'.-r')
h = impoly(gca,[0:2; sin(0:2)]');       % create impoly on the curve
setPositionConstraintFcn(h,@fcn)        % assign constraint

    function newPos = fcn(currPos)
        d = pdist2([x(:) y(:)],currPos);
        [~,ix] = min(d);                % find closest points
        newPos = [x(ix); y(ix)]';       % constrained position
    end
end

Answer 2

[Ameer Hamza]

You can use fimplicit() to get the points on the equation and then pass those points to impoly()

f = @(x, y) x.^2 + y.^2 - 5*x + 12*y + 24;
fi = fimplicit(f, [-3 8 -15 0]);
x = fi.XData;
y = fi.YData;

[Saikat Banerjee]

I construct impoly as h=impoly([-1,-5];[3,-1];[5,-8]); Now give the rest of the code. I can't understand

[Saikat Banerjee]

This answer is also of help but the other one is better