CairoMakie poly only respects transparency when setting alpha in color

[pfuchter]

If you set the transparency of a poly using alpha, it does not work. It only works if you set it as part of the color attribute

MWE:

  x1 = [0.,1,1,0,0]
  y1 = [0.,0,1,1,0]
  
  x2 = [0.5,1.5,1.5,0.5,0.5]
  y2 = [0.5,0.5,1.5,1.5,0.5]

  f1 = Figure()
  ax1 = Axis(f1[1,1],title="good")
  poly!(ax1,hcat(x1,y1),color=(:red,0.5))
  poly!(ax1,hcat(x2,y2),color=(:blue,0.5))

  ax2 = Axis(f1[1,2],title="bad")
  poly!(ax2,hcat(x1,y1),color=:red,alpha=0.5)
  poly!(ax2,hcat(x2,y2),color=:blue,alpha=0.5)
  
  save("test.pdf",f1)

[asinghvi17]

Which Makie versions was this on?

[pfuchter]

CairoMakie v0.11.9

[asinghvi17]

I can confirm this is also an issue on the 0.21 branch.

[jerlich]

this pops up also in density plots.

[ffreyer]

The example doesn't work for me anymore (did we remove a conversion?). Updated version:

begin
    x1 = [0.,1,1,0,0]
    y1 = [0.,0,1,1,0]
    
    x2 = [0.5,1.5,1.5,0.5,0.5]
    y2 = [0.5,0.5,1.5,1.5,0.5]
  
    f1 = Figure()
    ax1 = Axis(f1[1,1],title="good")
    poly!(ax1,Point2f.(x1,y1),color=(:red,0.5))
    poly!(ax1,Point2f.(x2,y2),color=(:blue,0.5))
  
    ax2 = Axis(f1[1,2],title="bad")
    poly!(ax2,Point2f.(x1,y1),color=:red,alpha=0.5)
    poly!(ax2,Point2f.(x2,y2),color=:blue,alpha=0.5)
    f1
end