Fields of Gravity

Stefan Abendroth
/
Fields of Gravity

on 28 Nov 2023

drawframe(1);

Write your drawframe function below

function drawframe(f)
    persistent r rs theta phi res gx gy c mp mv
    % initialize start values constants
    if isempty(mp)
        r=0.1;      % radius of spheres
        rs=32;      % resolution of spheres
        theta = pi*(-rs:2:rs)/rs;
        phi = (pi/2)*(-rs:2:rs)'/rs;   
        res=200;
        [gx,gy]=meshgrid(linspace(-1,1,res),linspace(-1,1,res));
        c=complex(gx,gy);
        mp=exp(j*(0:2:4)*pi/3)*0.7;
        mv=mp*j*0.039;
    end
    % move masses
    for i=1:length(mp)
        mp(i)=mp(i)+mv(i);
    end
    % calculate forces and new velocities
    for i=1:length(mp)
        mf=0;
        for p=mp
            dp=p-mp(i);
            d=abs(dp);
            if d>eps
                mf=mf+0.001*dp/d^3;
            end
        end
        mv(i)=mv(i)+mf;
    end
    gz=0*c;
    for p=mp
        sx = r*cos(phi)*cos(theta)+real(p);
        sy = r*cos(phi)*sin(theta)+imag(p);
        sz = 12*r*sin(phi)*ones(size(theta));
        surf(sx,sy,sz);
        hold on;
        gz=gz-1./abs(p-c).^2;
    end
    gz(gz<-20)=-20;
    surf(gx,gy,gz);
    shading interp;
    axis off;
    set (gca,'XLim',[-1,1],'YLim',[-1,1],'ZLim',[-19.9,1.5]);
    colormap(parula);
    lightangle(80,-40);
    lightangle(-90,60);
    hold off;
end

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Fields of Gravity
Stefan Abendroth