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Bouncy Ball
on 26 Oct 2024
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Cite your audio source here (if applicable):
drawframe(1);
Write your drawframe function below
function drawframe(f)
persistent hAx nBalls ballPatches ballX ballY ballR bps
% setup
if f==1
% store axes handle
hAx = gca();
% set axes/figure properties
set(hAx,...
'Visible','off',...
'Units','Normalized',...
'InnerPosition',[0 0 1 1],...
'XLim',[-1 1],...
'YLim',[0 2],...
'NextPlot','Add');
set(gcf,'Color',[0 0 0]);
% number of balls total
nBalls = 100;
% bounces/s
bps = 0.5;
% radii of the balls
ballR = [0.1,linspace(0.05,0,nBalls-1)];
% ball position coordinates
ballX = linspace(0,1.5,nBalls)'; % always the same
ballY = zeros(nBalls,1); % changes each frame
% graphics placeholders for the ball patches
ballPatches = gobjects(nBalls,1);
% colors of each ball
ballColors = flipud(hot(nBalls));
% create a patch object for each ball
for i = 1:nBalls
ballPatches(i) = patch(hAx,...
'XData',[],...
'YData',[],...
'FaceAlpha',1,...
'FaceColor',ballColors(i,:),...
'EdgeAlpha',0);
end
% change some properties on the main ball patch
set(ballPatches(1),...
'EdgeAlpha',1,...
'LineWidth',1,...
'EdgeColor',[0 0 0]);
% invert the stacking order
hAx.Children = flipud(hAx.Children);
end
% y position for each ball
ballY = abs(sin((((f-1)/96)*2*pi*(bps)-(0:nBalls-1).'/nBalls )*2));
for i = 1:nBalls
% get patch data
if ballY(i) < ballR(i) % ball is compressing
% get ellipse patch data
newY = max(ballY(i),0.5*ballR(i));
a = min(2*ballR(i)-ballY(i),1.5*ballR(i));
b = newY;
[XData,YData] = getEllipseCoordinates(ballX(i),newY,a,b);
else % ball is in the air
% get circle patch data
[XData,YData] = getCircleCoordinates(ballX(i),ballY(i),ballR(i));
end
% update patch data
set(ballPatches(i),...
'XData',XData,...
'YData',YData);
end
drawnow;
function [cX,cY] = getCircleCoordinates(centerX,centerY,r)
theta = (0:1:359)';
cX = r*cosd(theta)+centerX;
cY = r*sind(theta)+centerY;
end
function [cX,cY] = getEllipseCoordinates(centerX,centerY,a,b)
theta = (0:1:359)';
cX = a*cosd(theta)+centerX;
cY = b*sind(theta)+centerY;
end
end
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