as_colormap_movie.m

c=1; % speed of wave;
dx=1; % space step;
dt=0.1; % time step;


szx=200;
szy=200; % sizes
tm=2000; % time
k=0.002; % decay factor
dp=0.01; % droplet probability per one time sterp
dsz=3; % droplet size
da=0.07; % droplet amplitude

gf=0.3; % gradient factor

x=0:dx:(szx-dx);
y=0:dx:(szy-dx); % space
t=0:dt:tm; % time

[X,Y] = meshgrid(x,y);

Lx=length(x);
Ly=length(y);

u=zeros(Ly,Lx); % initial value
%u(50,70)=100; 
uo=u; % previose = curent => velocties =0

close all;
hf=figure;
ha=axes;
% hi=imshow(I);
hi=imagesc(x,y,u);
colorbar;
set(ha,'clim',[-1 1]);
axis equal;

% cyan colormap:
bl1=linspace(0,1,64)';
bl2=linspace(0.0,1,64)';
bl3=linspace(0.0,0,64)';
bl=[bl3 bl2 bl1];
colormap(bl);

D=[0 1 0; 1 -4 1; 0 1 0]; % 2d laplace operator

% sobel operator:
Gx=[-1 0 1; 
    -2 0 2;
    -1 0 1];
Gy=[-1 -2 -1;
    0 0 0;
    1 2 1];

kdt=k*dt;
c1=dt^2*c^2/dx^2;
lc=1;
dlc=15;
Ii=I;

% droplet as gaussian 
xd=-2*dsz:dx:2*dsz;
yd=-2*dsz:dx:2*dsz;
[Xd,Yd] = meshgrid(xd,yd);
Zd=-da*exp(-(Xd/dsz).^2-(Yd/dsz).^2);

lcms=10000; % start of movie record
clear F;
fc=1;
for tt=t
    un=(2-kdt)*u+(kdt-1)*uo+c1*conv2(u,D,'same'); % new
    
    uo=u; % curent become old
    u=un; % new become current
    
    if mod(lc-1,dlc)==0
        %Xi=X+gf*conv2(u,Gx,'same');
        %Yi=Y+gf*conv2(u,Gy,'same');
        %Ii(:,:,1) = interp2(X,Y,double(I(:,:,1)),Xi,Yi,'*linear',255);
        %Ii(:,:,2) = interp2(X,Y,double(I(:,:,2)),Xi,Yi,'*linear',255);
        %Ii(:,:,3) = interp2(X,Y,double(I(:,:,3)),Xi,Yi,'*linear',255);
        %set(hi,'CData',Ii);
        set(hi,'Cdata',u);
        drawnow;
        if lc>=lcms
            F(fc)=getframe(gcf);
            fc=fc+1;
        end
    end
    
    % droplets:
    if rand<dp
        x0d=2*dsz+1+(szx-4*dsz-2)*rand;
        y0d=2*dsz+1+(szy-4*dsz-2)*rand; % droplet center
        x0d=round(x0d);
        y0d=round(y0d);
        u(y0d-2*dsz:y0d+2*dsz,x0d-2*dsz:x0d+2*dsz)=...
            u(y0d-2*dsz:y0d+2*dsz,x0d-2*dsz:x0d+2*dsz)+Zd;
    end
    
    
    
    lc=lc+1;
end


% to avi:
movie2avi(F,'colormap_mov','compression','Cinepak','fps',20); % uncoment this to save the movie to avi file

% to gif:
fL0=length(F);
fL=100;
[im,map] = rgb2ind(F(1).cdata,256,'nodither');
st=2;
im(1,1,1,fL/st) = 0;
k1=1;
for kkk = 1:2:fL
  im(:,:,1,k1) = rgb2ind(F(k1).cdata,map,'nodither');
  k1=k1+1;
end
imwrite(im,map,'colormap_gif.gif','DelayTime',0,'LoopCount',inf) %g443800