Makie (GeoMakie + GLMakie) arrows doesn't use 'alpha=' parameter

General Usage
1

The docs for Makie arrows state

alpha

Defaults to 1.0

The alpha value of the colormap or color attribute. Multiple alphas like in plot(alpha=0.2, color=(:red, 0.5), will get multiplied.

However, it appears the color attribute alpha gets ignored at the moment.
Is this me or a bug?

MWE

using GeoMakie, GLMakie
a = [0]
b = [1]
alpha = 0.3
lw =10
ars= 50

fig = Figure()
ax = Axis( fig[1,1],  aspect=DataAspect())

# right arrow should be alpha but isn't
arrows!(a, a,  b, a, color=(:red), linewidth=lw, arrowsize=ars, alpha = alpha)

# left arrow is alpha  (as should be)
arrows!(a, a, -b, a, color=(:green, alpha), linewidth=lw, arrowsize=ars)

# top arrow should be alpha*alpha but is only alpha
arrows!(a, a,  a, b, color=(:blue, alpha), linewidth=lw, arrowsize=ars, alpha=alpha)

fig

arrows
arrows600×450 6.87 KB

2

There are many of these alpha bugs currently because while alpha gets merged into most plot objects’ theme by default (hence the docs entry) it currently needs to be linked to the child plots manually, and this was not done consistently.

1 Like
3

Thanks @jules for the clarification.

1 Like