How can I connect slider and angle in the GUI?

Hello, I want to make the GUI change the angle when using the slider.

for example, in this photo, the first slider moves the first angle from 0 to 2pi.

I think I need to connect the angle of the slider and the shape when I click the run button on the right, but I don't know how.

[Voss]

Can you please attach your .m file and .fig file (using the paperclip button)?

Answer 1

[Aravind]

Hi @SeokWon CHOI,

To adjust the angle of a shape in response to a slider's position when you press the run button, you can use a callback function associated with the button. This function will utilize a rotation matrix to change the shape's angle.

The process involves calculating a rotation matrix and applying it to the shape to update its angle. For 2D graphics, the rotation occurs around the Z-axis, and the rotation matrix is defined as:

where “θ” is the angle derived from the slider's current position.

This calculation can be performed in the callback function triggered when the button is pressed. More details on using callback functions for buttons can be found here: https://www.mathworks.com/help/releases/R2022a/matlab/ref/uibutton.html#buimxxx-1.

In the callback function for the button, you can use the following code to change the angle of a shape (such as a rectangle):

% Callback function for slider value change
function onSliderValueChanged(app, event)
angle = app.Slider.Value;
% Define the rotation matrix
R = [cos(angle), -sin(angle); sin(angle), cos(angle)];
% Define the original rectangle vertices
vertices = [-0.5, -0.2; 0.5, -0.2; 0.5, 0.2; -0.5, 0.2]';
% Rotate the vertices
rotatedVertices = R * vertices;
% Update the rectangle position
app.Rectangle.Vertices = rotatedVertices';
end

To create the rectangle, use:

app.Rectangle = patch(app.UIAxes, 'Vertices', vertices, 'Faces', [1, 2, 3, 4], 'FaceColor', 'blue');

For more information about the “patch” function, refer to this documentation page: https://www.mathworks.com/help/releases/R2022a/matlab/ref/patch.html.

I have included a simplified example where the rectangle's angle is adjusted based on the slider, along with its result for your reference.

I hope this helps answer your question.