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on 12 Nov 2023
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drawframe(1);
Write your drawframe function below
function drawframe(f)
persistent u n b M2 a2 a2_a r2
if f==1
u=@linspace;
n=@rescale;
b=@circshift;
q=400;
a=1.65;
m=0;
%sets up the colormap
g=[0.5373 0.1529 0.0824
0.6745 0.2353 0.1176
0.8706 0.3412 0.1647
0.9176 0.6353 0.2471
0.9843 0.9922 0.9725];
g=interp1(u(0,100,5),g,u(0,100,255));
g2=g-.15;
g2(g2<0)=0;
colormap([g;g2]);
% for the sunset have 2 different colourmaps for the background and the
% clouds then blend within each channel
%declare some functions and variables to save characters
X=u(1,255,200); %vector ranging between 1 and 255 200 long
X2=u(-1,1,400); %vector ranging between -1 and 1 400 long
[t2,r2]=cart2pol(X2,X2'+.1);%make radial gradient for the sun
M=n(-r2(1:200,:),1,280);%or for sun
X=u(-1,1,q);
[t,r]=cart2pol(X,X'); %create r matrix for filter in fourier transform
l1=d(r,a); %generate 3 cloud layers using filtered noise function
l2=-d(r,a);
l3=d(r,a);
i1=round(u(1,q,48)); %create 2 sets of indices for slow and fast moving cloud layers
i2=round(u(1,800,48));
[x,y] = meshgrid(0:399);
%smaller first constant creates wider cloud band (line below).
M3 = exp(-.007*(y-290).^2/4^2); % gaussian envelope in matrix to keep clouds in a specified band.
%pregenerate frames so all frames can be rescaled together
for k=1:48
%pairs of matrices define the pixelmap and the alpha
a1(:,:,1)=n(l1,-6,8); %first cloud layer doesn't move
a1_a(:,:,1)=n(l1,-6,8);
a1(:,:,2)=n(b(l2,i2(k),2),-6,8); %second cloud layer traverses the image once
a1_a(:,:,2)=n(b(l2,i2(k),2),-6,8);
a1(:,:,3)=n(b(-l3,i1(k),2),-6,8); %third cloud layer traverses the image twice
a1_a(:,:,3)=n(b(l3,i1(k),2),-6,8);
a2(:,:,k)=(max(a1,[],3)).*M3; %blend 3 cloud layers using a max function
a2_a(:,:,k)=(max(a1_a,[],3)).*M3; %blend 3 cloud layers using a max function
end
a2=n(abs(a2),-80,255);
a2_a=n(a2_a,0,1);
for k=1:48
M2(:,:,k)=M.*(1-(a2_a(201:400,:,k)))+(a2_a(201:400,:,k)).*a2(201:400,:,k); %blend alpha cloud layer with sky layer
end
%flip matrix and create sea currents using circshift
M2=n(M2,0,255);
end
D=flip(M2(:,:,f))+255;
% reflection from water
M4=M2(:,:,f);
M4(r2(1:200,:)<0.045)=255;%set sun colour
for k1=30:200
D(k1,197:203)=255+255-randi(80);
M4=[M4;b(D(k1,:),round(4*randn),2)];
end
image(M4)
axis equal
axis off
camva(4)
function c=d(r,a)
c=rescale(abs(ifft2(fftshift(fft2(randn(400))).*(r.^-a))),0,1).^1; %function to create clouds
end
end
Animation
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