%% E5 Lecture 7
%
% To use without saving videos, comment out all calls to E5Image().
clear all
clf
clc


%%  Define a shape
theta=0:10:360;   %theta is spaced around a circle (0 to 360).
r=1;              %The radius of our circle.
%Define a circular magenta patch.
x=r*cosd(theta);
y=r*sind(theta);
myShape=patch(x,y,'m');
axis(20*[-1 1 -1 1],'square');  grid on;

%%  Move it across the screen
T=0.25;                          %Delay between images
for x0=-15:2.5:15,
    set(myShape,'Xdata',x0+x);  %Translate by x0
    pause(T);                   %Wait T seconds
end

%%  Move it across the screen (different technique)
T=0.25;                          %Delay between images
x0=linspace(-15,15,20);
for i=1:length(x0),
    set(myShape,'Xdata',x0(i)+x);  %Translate by x0
    pause(T);                      %Wait T seconds
end

%%  Move it by giving it a velocity in x
vx=5;     %velocity in meters/sec.
dt=0.25;    %time step

x0=-10;
for t=0:dt:4,
    set(myShape,'Xdata',x+x0);              %Translate by x0
    pause(dt);                              %Wait dt seconds
    x0=x0+vx*dt;
end

%%  Move it by giving it a velocity in x and y
vx=5;     %velocity in meters/sec.
vy=10;
dt=0.25;    %time step

x0=-10;
y0=-10;
for t=0:dt:3,
    set(myShape,'Xdata',x+x0,'Ydata',y+y0); %Translate by x0.y0
    pause(dt);                              %Wait dt seconds
    x0=x0+vx*dt;
    y0=y0+vy*dt;
end


% %%  Add gravity
vx=5;     %velocity in meters/sec.
vy=15;
dt=0.2;   %time step

x0=-15;
y0=0;
for t=0:dt:4,
    set(myShape,'Xdata',x+x0,'Ydata',y+y0);   %Translate by x0, y0
    pause(dt);                                %Wait dt seconds
    x0=x0+vx*dt;
    y0=y0+vy*dt;
    vy=vy-9.8*dt;
end

%%  Add a border and collisions
vx=5;     %velocity in meters/sec.
vy=20;
dt=0.15;   %time step

x0=-14;
y0=0;

hold on;
plot([-15 -15 15 15 -15],[15 -15 -15 15 15],'b','LineWidth',2);

for t=0:dt:10,
    set(myShape,'Xdata',x+x0,'Ydata',y+y0);   %Translate by x0, y0
    pause(dt);                                %Wait dt seconds
    x0=x0+vx*dt;     %update x postion
    y0=y0+vy*dt;     %update y postion   
    E5Image('add');
    vy=vy-9.8*dt;    %update y velocity
    if x0>=15-r,     %check for collision with right side
        vx=-vx;          %if so, reverse x velocity
        x0=15-r;         %reset x position so it touches wall
    elseif x0<=-15+r,%check for collision with left side...
        vx=-vx;
        x0=-15+r;
    end
    if y0>=15-r,     %check for collision with top
        vy=-vy;
        y0=15-r;
    elseif y0<=-15+r,%check for collsion with bottom
        vy=-vy;
        y0=-15+r;
    end
end
E5Image('save','E5Lect7_Ex6',dt);

%%  Add inelastic collisions
vx=5;     %velocity in meters/sec.
vy=20;
dt=0.1;   %time step
x0=-14;
y0=0;% 

hold on;
plot([-15 -15 15 15 -15],[15 -15 -15 15 15],'b','LineWidth',2);
p=0.7;
for t=0:dt:15,
    set(myShape,'Xdata',x+x0,'Ydata',y+y0);   %Translate by x0, y0
    pause(dt);                                %Wait dt seconds
    x0=x0+vx*dt;   %update x position
    y0=y0+vy*dt;   %update y position
    
    vy=vy-9.8*dt;  %update y velocity
    if x0>=15-r,   %check for right wall
        vx=-vx*p;     %if hit, reverse (and decrease) velociy
        x0=15-r;
    elseif x0<=-15+r, %left wall
        vx=-vx*p;
        x0=-15+r;
    end
    if y0>=15-r,      %top
        vy=-vy*p;
        y0=15-r;
    elseif y0<=-15+r, %bottom
        vy=-vy*p;
        y0=-15+r;
    end
end

%%  Animate until done
vx=5;     %velocity in meters/sec.
vy=20;
dt=0.1;   %time step
x0=-14;
y0=0;% 

hold on;
plot([-15 -15 15 15 -15],[15 -15 -15 15 15],'b','LineWidth',2);
p=0.7;
while (abs(vx)>2) | (abs(vy)>2) | (y0<-15+2*r),
    set(myShape,'Xdata',x+x0,'Ydata',y+y0);   %Translate by x0, y0
    pause(dt);                                %Wait dt seconds
    x0=x0+vx*dt;   %update x position
    y0=y0+vy*dt;   %update y position
    vy=vy-9.8*dt;  %update y velocity
    if x0>=15-r,   %check for right wall
        vx=-vx*p;     %if hit, reverse (and decrease) velociy
        x0=15-r;
    elseif x0<=-15+r, %left wall
        vx=-vx*p;
        x0=-15+r;
    end
    if y0>=15-r,      %top
        vy=-vy*p;
        y0=15-r;
    elseif y0<=-15+r, %bottom
        vy=-vy*p;
        y0=-15+r;
    end
end