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

**URL:** https://discourse.julialang.org/t/makie-geomakie-glmakie-arrows-doesnt-use-alpha-parameter/122339
**Category:** General Usage
**Tags:** plotting
**Created:** [November 6, 2024, 3:32pm UTC](https://discourse.julialang.org/t/makie-geomakie-glmakie-arrows-doesnt-use-alpha-parameter/122339 "2024-11-06T15:32:25Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![RobbesU](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/robbesu/32/212459_2.png) [@RobbesU](https://discourse.julialang.org/u/RobbesU)
#### Post date: [November 6, 2024, 3:32pm UTC](https://discourse.julialang.org/t/makie-geomakie-glmakie-arrows-doesnt-use-alpha-parameter/122339/1 "2024-11-06T15:32:25Z")

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The [docs for Makie arrows](https://docs.makie.org/stable/reference/plots/arrows#alpha) 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

```julia
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](https://global.discourse-cdn.com/julialang/original/3X/7/f/7f441181ca757e85c126871b31d64a1eb8e6294d.png)

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<div class="post-metadata">

### Author: ![jules](https://avatars.discourse-cdn.com/v4/letter/j/41988e/32.png) [@jules](https://discourse.julialang.org/u/jules)
#### Post date: [November 6, 2024, 4:15pm UTC](https://discourse.julialang.org/t/makie-geomakie-glmakie-arrows-doesnt-use-alpha-parameter/122339/2 "2024-11-06T16:15:44Z")

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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.

---

<div class="post-metadata">

### Author: ![RobbesU](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/robbesu/32/212459_2.png) [@RobbesU](https://discourse.julialang.org/u/RobbesU)
#### Post date: [November 6, 2024, 7:23pm UTC](https://discourse.julialang.org/t/makie-geomakie-glmakie-arrows-doesnt-use-alpha-parameter/122339/3 "2024-11-06T19:23:28Z")

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Thanks @jules for the clarification.