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  • Endless tunnel

on 6 Nov 2023
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drawframe(1);
Write your drawframe function below
% % % Endless Tunnel
%
% How this works:
% - A torus is generated with texture that is periodic at pi/4 intervals
% - The camera is moved around a quarter of the torus so that looping has
% no discontinuities.
%
% We are swimming in characters this year so this could be significantly
% compressed and more features added!
function drawframe(nn)
% This enables the same "random" texture to be created every time
rng default;
r=6; % Torus radius
N=80; % Texture resolution. Set to higher on your own computer for improvements.
% (Has longer rendering times!)
R=zeros(N, N*8); % Initial torus radius
R(:,N/2:N:end)=-.02; % Notches every bit
R=conv2(R,[1:4,3:-1:1],'same'); % Fare the notches
R=R+conv2(randn(size(R))/500,ones(3)/9,'same')+1; % Add some random noise. Probably doesn't do a whole
% lot for N = 80.
R(end, :)=R(1, :); % Match endpoints to prevent a glitch
% Make angles for torus (radial and axial)
l=@(x)linspace(0,2*pi,x);
ag1=l(N)';
ag2=l(N*8);
% This will be the tunnel
b=R.*cos(ag1);
z=R.*sin(ag1);
x=b.*cos(ag2)+r*cos(ag2);
y=b.*sin(ag2)+r*sin(ag2);;
% This will be the algae growing on the pipe
R2=R*.99;
b=R2.*cos(ag1);
z2=R2.*sin(ag1);
x2=b.*cos(ag2)+r*cos(ag2);
y2=b.*sin(ag2)+r*sin(ag2);
% This will eventually be the water at the bottom
rd=linspace(4, 8, N)';
xd=rd.*cos(ag2);
yd=rd.*sin(ag2);
% Make camera positions
ag=linspace(0,2*pi,48*4);
cpx=r*cos(ag);
cpy=r*sin(ag);
cpz=zeros(size(cpx))-0.2;
% Texture: this will be the water. Making a complex random
% function. Noise generated spectrally like this has looping boundaries /
% can be tiled, so it is tiled for start/end consistency
[xx,yy]=meshgrid(linspace(-1,1,N*8),linspace(-1,1,N));
rd=sqrt(xx.^2+yy.^2);
sgnO=((randn(N, N*8)+1i*randn(N, N*8))./((ifftshift(rd.^2)+1e-5)));
sgnO=ifft2(sgnO(:,[1:N,end-N+1:end]));
sgnO=[sgnO,sgnO,sgnO,sgnO];
% This will be the algae on the side.
sg=(((randn(N,N*8)+1i*randn(N, N*8))./((ifftshift(rd.^2)+1e-6))));
sg=real(ifft2(sg(:, 1:N*2)));
sg=[sg,sg,sg,sg];
sg=erf(sg*2)+1;
sg=-sg.*(1-erf(sin(ag1)+1));
% This will be our phase looper. Since the water phase noise is complex, we
% can loop over 2*pi to get a splashing effect
ags=linspace(0, pi/4, 49);
ags=ags(1:48);
clf % Lights seem to accumulate without this...
% Algae color
clrF = permute([0.3, 0.5, 0.3]*0.4, [1, 3, 2]);
% Faster if we limit the number of faces generated each frame... this
% truncates the rendered portion of the torus to what is visible
[~, ci] = min(abs(ag2-ag(nn)));
rgv = (1:N*2) + ci;
% Update water noise using a phase rotation
sgn = real(sgnO.*exp(1i*ags(nn)*16));
sgn = sgn - mean(sgn(:));
sgn = erf(1*sgn/std(sgn(:)));
% Truncate
sgn = sgn(:, rgv);
sg = sg(:, rgv);
idz = N*8;
% Begin plotting
clr = (conv2(rand(N, N*8), ones(5)/25, 'same')*0.3+0.7).*ones(N, N*8, 3)*0.5;
surf(x(:, rgv), y(:, rgv), z(:, rgv), clr(:, rgv, :), 'SpecularStrength', 1, 'AmbientStrength', 0);
hold on;
surf(x2(:, rgv), y2(:, rgv), z2(:, rgv), (rand(size(sgn))*0.2+0.8).*clrF, 'FaceAlpha', 'flat', 'AlphaData', erf(rescale(1-sg)*2+0.5)*1, 'SpecularStrength', 0, 'AmbientStrength', 0);
surf(xd(:, rgv), yd(:, rgv), rand(size(sgn))*0.002 + sgn/20-0.8, 'FaceAlpha', 0.9, 'AmbientStrength', 0, 'DiffuseStrength', 0.35, 'SpecularStrength', 1);
% Appearance and camera settings
shading interp
axis equal
camproj('Perspective');
camva(50);
campos([cpx(nn), cpy(nn), cpz(1)+sin(ags(nn)*16)/6 - 0.2]);
camtarget([cpx(nn+18), cpy(nn+18), cpz(nn+18)-0.4]);
% Headlight: one doesn't seem strong enough
camlight;
camlight
D = camlight;
D.Color = [0.6, 0.8, 1];
% This is inefficient, should just directly set water color in the call to
% surf but you can pick a different colormap to alter the water color here
cmp = copper + summer;
colormap(cmp/2);
caxis([-1, 1]);
% S.D.G.
end
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