Ball trapped inside a car

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Robert Mirea
Robert Mirea 2022-5-27
回答： VINAYAK LUHA 2023-9-21
Ran in:
I have a car moving forward and i ned to trap a ball inside it.
x_casa = [2,12,12,7,2];
y_casa = [1,1,10,14,10]; %obiectul casa
casa = hgtransform;
patch('XData',x_casa,'YData',y_casa,'FaceColor','white','Parent',casa)
x_drum=[2,2 , 100 , 100 ];
y_drum=[1, 1.2 , 1.2 ,1]; %obiectul drum
drum = hgtransform;
patch('XData',x_drum,'YData',y_drum,'FaceColor','black','Parent',drum)
roata_spate = hgtransform; %back wheel
theta = 0:0.1:2*pi;
rad=0.3;
xCent = 13.5;
yCent = 1.3;
xCoord = xCent+rad*cos(theta);
yCoord = yCent+rad*sin(theta);
patch('XData',xCoord,'YData',yCoord,'FaceColor','blue','Parent',roata_spate)
roata_fata = hgtransform; %front wheel
theta = 0:0.1:2*pi;
rad=0.3;
xCent2 = 16;
yCent2 = 1.3;
xCoord2 = xCent2+rad*cos(theta);
yCoord2 = yCent2+rad*sin(theta);
patch('XData',xCoord2,'YData',yCoord2,'FaceColor','blue','Parent',roata_fata)
x_sasiu = [12.5, 17.5, 17.5, 15.5, 12.5, 12.3]; % car chassis
y_sasiu = [1.6, 1.6, 3, 4 , 4 , 1.6];
sasiu = hgtransform;
patch('XData',x_sasiu,'YData',y_sasiu,'FaceColor','white','Parent',sasiu)
ball = hgtransform; %ball
theta = 0:0.1:2*pi;
rad=1;
xCent3 = 15;
yCent3 = 2.7;
xCoord3 = xCent3+rad*cos(theta);
yCoord3 = yCent3+rad*sin(theta);
patch('XData',xCoord3,'YData',yCoord3,'FaceColor','red','Parent',ball)
axis equal
xlim([0 100])
ylim([0 30])
pt1 = [0 0 0];
pt2 = [80 0 0];
for t=linspace(0,1,2500) %making the car moving forward
sasiu.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
roata_fata.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
roata_spate.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
drawnow
end
  3 个评论
显示 1更早的评论
Walter Roberson
Walter Roberson 2022-5-29
Instead of having the ball have independent coordinates, parent it to the car, so that when the car moves it automatically moves as well. The coordinates of the ball at any time should be the position of the ball relative to some reference point inside the car.
It is legal to have one hgtransform be parented to another.
Robert Mirea
Robert Mirea 2022-5-30
and how shoul i do independent coordinates for the car ? i am pretty new to the coding an i don't know how to do that.

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回答（1 个）

VINAYAK LUHA
VINAYAK LUHA 2023-9-21
Hi Robert Mirea,
It is my understanding that you would like to have the ball trapped inside the car such that it moves along with the latter.
Here’s a workaround in which the ball.matrix transformation is updated using the same translation transformation applied to the car chassis. This ensures that the ball remains trapped inside the car as it moves forward. I’ve also updated the “yCoord3” variable such that the ball fits inside the car.
Here’s the modified code for your reference-
x_casa = [2,12,12,7,2];
y_casa = [1,1,10,14,10]; %obiectul casa
casa = hgtransform;
patch('XData',x_casa,'YData',y_casa,'FaceColor','white','Parent',casa)
x_drum=[2,2 , 100 , 100 ];
y_drum=[1, 1.2 , 1.2 ,1]; %obiectul drum
drum = hgtransform;
patch('XData',x_drum,'YData',y_drum,'FaceColor','black','Parent',drum)
roata_spate = hgtransform; %back wheel
theta = 0:0.1:2*pi;
rad=0.3;
xCent = 13.5;
yCent = 1.3;
xCoord = xCent+rad*cos(theta);
yCoord = yCent+rad*sin(theta);
patch('XData',xCoord,'YData',yCoord,'FaceColor','blue','Parent',roata_spate)
roata_fata = hgtransform; %front wheel
theta = 0:0.1:2*pi;
rad=0.3;
xCent2 = 16;
yCent2 = 1.3;
xCoord2 = xCent2+rad*cos(theta);
yCoord2 = yCent2+rad*sin(theta);
patch('XData',xCoord2,'YData',yCoord2,'FaceColor','blue','Parent',roata_fata)
x_sasiu = [12.5, 17.5, 17.5, 15.5, 12.5, 12.3]; % car chassis
y_sasiu = [1.6, 1.6, 3, 4 , 4 , 1.6];
sasiu = hgtransform;
patch('XData',x_sasiu,'YData',y_sasiu,'FaceColor','white','Parent',sasiu)
ball = hgtransform; %ball
theta = 0:0.1:2*pi;
rad=1;
xCent3 = 15;
yCent3 = 2.7;
xCoord3 = xCent3+rad*cos(theta);
yCoord3 = yCent3+rad*sin(theta);
patch('XData',xCoord3,'YData',yCoord3-2.5,'FaceColor','red','Parent',ball)
axis equal
xlim([0 100])
ylim([0 30])
pt1 = [0 0 0];
pt2 = [80 0 0];
for t=linspace(0,1,2500) %making the car moving forward
sasiu.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
roata_fata.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
roata_spate.Matrix = makehgtform('translate',pt1 + t*(pt2-pt1));
%%Update the position of the ball relative to the car
ball.Matrix = makehgtform('translate',[pt1(1) + t*(pt2(1)-pt1(1)), yCent3, 0]);
drawnow
end
Regards
Vinayak Luha

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