Fix gap in miter join

[ffreyer]

Description

#2953 introduced a gap in miter joins that I and refimg tests didn't catch:

The pr fixes that.

To fix anti-aliasing for strongly varying linewidths I added extra AA padding in width direction in #2953. This extra padding is communicated to the fragment shader through and increased linewidth, set in an emit_vertex method. The problem is that this method is also used for the triangle used in miter joins, which does not get any extra AA padding. So there is a missmatch between the real width and the reported width, resulting in the AA edge getting missplaced.

After the changes:

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• Added an entry in NEWS.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.

[MakieBot]

Compile Times benchmark

Note, that these numbers may fluctuate on the CI servers, so take them with a grain of salt. All benchmark results are based on the mean time and negative percent mean faster than the base branch. Note, that GLMakie + WGLMakie run on an emulated GPU, so the runtime benchmark is much slower. Results are from running:

using_time = @ctime using Backend
# Compile time
create_time = @ctime fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @ctime Makie.colorbuffer(display(fig))
# Runtime
create_time = @benchmark fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @benchmark Makie.colorbuffer(display(fig))

	using	create	display	create	display
GLMakie	11.64s (11.54, 11.72) 0.07+-	1.05s (1.04, 1.06) 0.01+-	782.19ms (755.29, 832.21) 24.39+-	10.62ms (10.55, 10.69) 0.05+-	88.69ms (88.20, 89.45) 0.52+-
master	11.61s (11.51, 11.78) 0.10+-	1.09s (1.08, 1.10) 0.01+-	773.36ms (769.51, 779.43) 4.04+-	10.82ms (10.68, 10.93) 0.07+-	88.72ms (87.75, 89.61) 0.59+-
evaluation	+0.27%, 0.03s invariant (0.38d, 0.49p, 0.08std)	-3.50%, -0.04s faster ✓ (-6.05d, 0.00p, 0.01std)	+1.13%, 8.82ms invariant (0.50d, 0.38p, 14.21std)	-1.90%, -0.2ms faster ✓ (-3.15d, 0.00p, 0.06std)	-0.03%, -0.03ms invariant (-0.05d, 0.92p, 0.56std)
CairoMakie	10.12s (10.03, 10.26) 0.08+-	1.25s (1.22, 1.27) 0.02+-	261.27ms (253.53, 265.65) 4.44+-	10.47ms (10.31, 10.68) 0.12+-	6.01ms (5.87, 6.12) 0.11+-
master	10.11s (9.88, 10.31) 0.16+-	1.25s (1.21, 1.32) 0.04+-	261.49ms (250.71, 271.14) 7.22+-	10.46ms (10.12, 10.81) 0.25+-	6.15ms (5.88, 7.14) 0.45+-
evaluation	+0.13%, 0.01s invariant (0.11d, 0.85p, 0.12std)	-0.50%, -0.01s invariant (-0.21d, 0.70p, 0.03std)	-0.08%, -0.22ms invariant (-0.04d, 0.95p, 5.83std)	+0.06%, 0.01ms invariant (0.03d, 0.95p, 0.19std)	-2.23%, -0.13ms invariant (-0.41d, 0.47p, 0.28std)
WGLMakie	16.28s (15.64, 16.80) 0.42+-	1.74s (1.67, 1.85) 0.07+-	14.70s (14.37, 15.16) 0.25+-	19.23ms (16.93, 23.99) 2.34+-	1.46s (1.42, 1.50) 0.03+-
master	16.11s (15.83, 16.44) 0.23+-	1.70s (1.64, 1.80) 0.05+-	14.86s (14.45, 15.59) 0.36+-	19.76ms (17.85, 21.66) 1.45+-	1.47s (1.44, 1.50) 0.02+-
evaluation	+1.03%, 0.17s invariant (0.50d, 0.38p, 0.32std)	+2.19%, 0.04s invariant (0.63d, 0.26p, 0.06std)	-1.09%, -0.16s invariant (-0.51d, 0.36p, 0.31std)	-2.75%, -0.53ms invariant (-0.27d, 0.62p, 1.89std)	-0.86%, -0.01s invariant (-0.45d, 0.42p, 0.03std)