fix contourf Inf value on non-extended case

[t-bltg]

Description

Fix #3683.

x = y = LinRange(0, 1, 10)
ymin, ymax = 0.4, 0.6
steepness = 0.1
f(x, y) = (tanh((y - ymin) / steepness) - tanh((y - ymax) / steepness) - 1)
z = [f(_x, _y) for _x in x, _y in y]

fig, ax, cof = contourf(x, y, z)
Colorbar(fig[1, 2], cof)
save("noext.png", fig)

fig, ax, cof = contourf(x, y, z; extendhigh=:auto)
Colorbar(fig[1, 2], cof)
save("ext.png", fig)

noext

ext

Type of change

Delete options that do not apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• Added an entry in CHANGELOG.md (for new features and breaking changes)
• Added or changed relevant sections in the documentation
• Added unit tests for new algorithms, conversion methods, etc.
• Added reference image tests for new plotting functions, recipes, visual options, etc.

[jkrumbiegel]

I don't think this fixes the real bug, in my understanding contourf(x, y, z) should also have the gap filled, no? For some reason, one of the isobands is treated like it's out of range.

When I do highs[end] += eps(highs[end]) after the line highs = levels[2:end] it actually fills the gap.

[t-bltg]

Isn't the root of this bug due to the Float32 -> Float64 conversion in https://github.com/jkrumbiegel/Isoband.jl/blob/28058449fb3c08dc531d851686e920fe6ca3138e/src/Isoband.jl#L27 ?

Should https://github.com/jkrumbiegel/isoband/blob/6994b367c7af3c0e31c8c4b103850772bff818c6/src/isoband.cpp#L1701C26-L1701C39 also be implemented for floats since Makie is mostly Float32 based ?

[jkrumbiegel]

I don't think Float32 to Float64 conversion is the problem. Any Float32 is directly representable in Float64 I think, so there should be no mismatch. Somethings definitely wrong here though, would be good to get that logic straight

[t-bltg]

Let's try jkrumbiegel/Isoband.jl#2.

Using float doesn't hurt (faster).

[jkrumbiegel]

superseded by #3713