One way is to set the FaceColor directly:
% random data:
x_values = 1:10;
data = rand(10,5);
color1 = [0.3, 0.5, 0.7]; % RGB color for Y1
color2 = [0.8, 0.2, 0.2]; % RGB color for Y2
color3 = [0.5, 0.2, 0.9]; % Adjusted RGB color for Y3 (violet)
% Plotting
figure('Position', [100, 100, 800, 600]);
% Define the x-coordinates for each group of bars
x_pos = 1:numel(x_values);
Stack_Parameters = {'AC','JRCP\_Base','Base/Subbase/Subgrade'};
y1_MD = data(:,[1,3,5]);
y_sum_MD=sum(y1_MD,2);
y_MD=(y1_MD./y_sum_MD)*100;
hb = bar(x_pos,y_MD,'stacked');
% Set custom colors for each bar
set(hb,{'FaceColor'},{color1; color2; color3})
% Show all values in the bars
%text(x_pos, y(:,1), compose('%.1f%%', data(:, 1)), 'HorizontalAlignment', 'center', 'VerticalAlignment', 'bottom');
%text(x_pos, percent_group1 + percent_group2, compose('%.1f%%', data(:, 2)), 'HorizontalAlignment', 'center', 'VerticalAlignment', 'bottom');
ylabel('Percentage, %');
% Set y-axis limit to 100%
ylim([0 100]);
xticks(x_pos);
title('FWD 3 Layered Analysis (Modulus)');
xlabel('Station');
legend(Stack_Parameters,'Location', 'best','orientation','horizontal');
