Artefacts in 3D plotting after view rotation

Hello!

I'm using fill3 to generate ploygons for 3D plotting of areas in layers. Afterwards, I rotat the view into the desired angle. The areas are transparent to generate the imperssion of 3D when multiple layers overlap in the view:

startX = 1;
startY = 1;
startZ = 1;
ai = 2;
bi = 3; 

fig = figure(1);
hold on

layerOffset =2;
layerTextOffset = layerOffset + .5;

xMin = min(startX) - layerOffset;
xMax = max(startX +ai) + layerOffset;
yMin = min(startY) - layerOffset;
yMax = max(startY + bi) + layerOffset;
zMin = min(startZ);
zMax = max(startZ);

for z = 1:max(startZ)
    fill3( [xMin xMin xMax xMax], [yMin yMax yMax yMin], [z z z z],...
        [.6, .6, .6], ...
        'FaceAlpha', .1, ...
        'FaceLighting', 'gouraud', ...
        'EdgeColor', 'none', ...
        'EdgeAlpha',.5, ...
        'LineStyle', ':', 'LineWidth', 2);
    layerText = ['Layer ', num2str(z)];
    text( xMax + layerTextOffset, mean([yMin, yMax]),...
        z, layerText, ...
        'HorizontalAlignment', 'left',...
        'FontName', 'Palatino Linotype');
end

for i =1:length(startX)
    x1 = startX(i);
    x2 = startX(i)+ai(i);
    x3 = startX(i)+ai(i);
    x4 = startX(i);
    y1 = startY(i);
    y2 = startY(i);
    y3 = startY(i)+bi(i);
    y4 = startY(i)+bi(i);
    z = startZ(i);
    fill3( [x1 x2 x3 x4], [y1 y2 y3 y4], [z z z z],...
        'k',... 
        'FaceAlpha', .7-(z*0.2), ...
        'EdgeColor', 'b', ...
        'FaceLighting', 'gouraud', ...
        'EdgeAlpha',.5, ...
        'LineStyle', ':', 'LineWidth', 2);
    textOffsetX = 0.2;
    textOffsetY = .3;
    textContent = ['Area ', num2str(i)];
    text(mean([x1, x3]), mean([y2, y3]), z, ...
        textContent, ...
        'HorizontalAlignment', 'center',...
        'FontName', 'Palatino Linotype'); 
end

az = 22;
el = 54;
view(az, el);

print(fig, 'error.png', '-dpng')

Unfortunatly, the plots have errors after the rotation:

How do I avoid these artefacts?

Thanks for your kind responses, jmj