legend for transparent patch object is opaque ?
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Hello,
I create a simple figure with 2 patch objects where one of the patch is opaque and the other one is transparent (with facealpha set to 0.1) :
figure
x = [0 1 1 0];
y = [0 0 1 1];
patch(x,y,'red')
x2 = [3 6 6 3];
y2 = [3 3 6 6];
patch(x2,y2,'green','facealpha',0.1)
legend('red opaque -> OK','green is opaque instead of transparent -> WHY ?')
The legend does not reflect the fact that the green patch is transparent. I really need my legend to show if the patch is transparent or opaque. Is there a work around ?
Thanks !
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Réponse acceptée
Ameer Hamza
le 23 Juin 2018
The problem is actually caused by the Rendrer of the figure object. In R2018a opengl seems to make the legend entries transparent, but in prior versions, you need to switch to 'painters' renderer to get this behavior. For example, try the following
f = figure;
f.Renderer = 'painters';
x = [0 1 1 0];
y = [0 0 1 1];
patch(x,y,'red')
x2 = [3 6 6 3];
y2 = [3 3 6 6];
patch(x2,y2,'green','facealpha',0.1)
legend({'red opaque -> OK','green is opaque instead of transparent -> WHY ?'}, 'Box', 'off')
2 commentaires
Walter Roberson
le 23 Juin 2018
Traditionally only opengl supported transparency, but R2014b added transparency for painters
Plus de réponses (1)
Yun Guo
le 22 Juin 2018
It is not very clear if you want green patch to be transparent, legend to be transparent, or both.
'facealpha' does work as expected. See example below.
- I changed the green patch's size so it overlaps with red patch to show transpareny works.
- I also removed legend box, so legend looks transparent.
figure
x = [0 1 1 0];
y = [0 0 1 1];
patch(x,y,'red');
x2 = [0.5 2 2 0.5];
y2 = [0.5 0.5 2 2];
patch(x2,y2,'green','facealpha',0.3)
l = legend('red opaque -> OK','green is opaque instead of transparent -> WHY ?');
set(l, 'Box', 'off')
5 commentaires
Ameer Hamza
le 22 Juin 2018
I am trying on R2018a. Since you have R2017b, which I cannot try at the moment. But to correctly check the opacity move the legend over the red portion like this
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