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Move bar in ponggame with arrowkeys

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Ilse van der Veen
Ilse van der Veen on 9 Feb 2021
Answered: Manas Meena on 12 Feb 2021
For a schoolproject I am programming a pong ball game. I want to move the bar using the arrowkeys on my keyboard, but can only find a global function that works. But I actually want to avoid using global functions. Does someone have an alternative for me?
clear, clc, clf, clear all;
% ----------------------------- Lay out ----------------------------------%
Background = figure('color', [.2 .3 .8], 'KeyPressFcn', @keyboardFunction);
xaxis = [0 100];
yaxis = [-5 100];
GameField = axes('color', 'black', 'xlim', [xaxis(1) xaxis(2)],...
'ylim', [yaxis(1) yaxis(2)], 'xticklabels', [], ...
'yticklabels', []) %How to put axis off?
PosBall =[20 40] %Initial position ball
VelBall =[1 1] %Initial direction ball
Ball = line(PosBall(1),PosBall(2),'Marker', 'o', 'MarkerSize',...
10, 'MarkerFaceColor', 'white','MarkerEdgeColor','white') %Actual ball
global CenterBar = 45;
Bar = line([CenterBar - 5, CenterBar + 5], [0 0], 'LineWidth', 4, 'Color', 'b')
% -------------------------Control ball-----------------------------------%
tic;
while toc <20
if PosBall(1) < xaxis(1) || PosBall(1) > xaxis(2)
VelBall(1) = - VelBall(1);
end
if PosBall(2) > yaxis(2)
VelBall(2) = -VelBall(2);
end
if PosBall(2) < yaxis(1)
if abs(PosBall(1) - CenterBar) < 5
VelBall(2) = -VelBall(2);
else
disp("You lost the game!")
close all;return;
end
end
PosBall = PosBall + VelBall;
set(Ball, 'Xdata', PosBall(1), 'Ydata', PosBall(2));
set(Bar, 'Xdata', [CenterBar - 5, CenterBar + 5])
pause(.02);
end
function keyboardFunction(figure, event)
global CenterBar
switch event.Key
case 'leftarrow'
CenterBar = CenterBar - 2;
case 'rightarrow'
CenterBar = CenterBar + 2;
end
end

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