Lines in WGLMakie are not inspectable

[kbarros]

In the GLMakie backend, the objects produced by linesegments! can be inspectable. However, in WGLMakie, it seems they cannot.

Minimum working example:

using WGLMakie # works with GLMakie

fig = Figure()
ax = LScene(fig[1,1])
segments = [Point3f(1,0,0), Point3f(0,1,0)]
linesegments!(ax, segments; inspectable=true)
DataInspector(ax)

• are you running newest version (version from docs) ?

Tested on WGLMakie v0.9.2.

• What platform + GPU are you on?

Julia Version 1.10.0-rc3
Commit ed79752b939 (2023-12-18 09:57 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin22.4.0)
  CPU: 8 × Apple M1 Pro
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, apple-m1)
  Threads: 1 on 6 virtual cores

[kbarros]

A workaround might be to plot line segments as cylinders, but then I encounter other issues, cf. #3512 and #3513.

If those two are fixed before this issue, then here is an alternative to linesegments! that uses cylinders:

using WGLMakie, LinearAlgebra

function linesegmenttubes!(ax, pts; tubewidth, quality=32, kwargs...)
    marker = Makie._mantle(Makie.Point3f0(0, 0, -1/2), Makie.Point3f0(0, 0, 1/2), 1/2, 1/2, quality)
    @assert iseven(length(pts))
    x = pts[begin:2:end-1]
    y = pts[begin+1:2:end]
    pos = @. Makie.Point3f0((x + y) / 2)
    dirs = @. Makie.Vec3f0(y - x)
    markersize = [Makie.Vec3f0(tubewidth, tubewidth, norm(dir)) for dir in dirs]
    rotation = normalize.(dirs)
    Makie.meshscatter!(ax, pos; markersize, rotation, marker, kwargs...)
end

fig = Makie.Figure()
ax = Makie.LScene(fig[1, 1])
pts = [[0, 0, 0], [1, 0, 1], [2, 0, 1], [2, -1, 0]]
color = [:red, :blue]
linesegmenttubes!(ax, pts; tubewidth=0.1, quality=12, color)
Makie.DataInspector(ax; indicator_color=:gray)

[kbarros]

Thanks a lot for looking into it. It's close, but there still seems to be a problem. Consider this slightly more complicated script:

begin
    fig = Figure()
    ax = LScene(fig[1,1])
    segments = [Point3f(1,0,0), Point3f(0,1,0), Point3f(0, 0, 1), Point3f(1, 0, 1)]
    color = [:red, :blue]
    inspector_label(_, i, _) = ["hello", "world", "nice", "day"][mod1(i, 4)]
    linesegments!(ax, segments; color, inspectable=true, inspector_label)
    DataInspector(ax)
    fig
end

• GLMakie behavior: Inspecting the red line prints "world" and inspecting the blue line prints "day". Tooltip location follows mouse.
• WGLMakie behavior: Inspecting the blue line almost works. Sometimes the tooltip follows the cursor and prints "day" like in GLMakie. Sometimes the tooltip snaps to the top-right and prints instead "nice" (see two images below). Inspecting the red line throws an error with the following stack trace:

┌ Warning: Error in window event callback
│   exception =
│    BoundsError: attempt to access 4-element Vector{Point{3, Float32}} at index [0:1]
│    Stacktrace:
│      [1] throw_boundserror(A::Vector{Point{3, Float32}}, I::Tuple{UnitRange{Int64}})
│        @ Base ./abstractarray.jl:734
│      [2] checkbounds
│        @ Base ./abstractarray.jl:699 [inlined]
│      [3] getindex(A::Vector{Point{3, Float32}}, I::UnitRange{Int64})
│        @ Base ./array.jl:973
│      [4] position_on_plot(plot::LineSegments{Tuple{Vector{Point{3, Float32}}}}, idx::Int64, ray::Makie.Ray; apply_transform::Bool)
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/ray_casting.jl:254
│      [5] position_on_plot
│        @ ~/.julia/packages/Makie/Qvk4f/src/interaction/ray_casting.jl:253 [inlined]
│      [6] position_on_plot(plot::LineSegments{Tuple{Vector{Point{3, Float32}}}}, idx::Int64; apply_transform::Bool)
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/ray_casting.jl:235
│      [7] position_on_plot
│        @ ~/.julia/packages/Makie/Qvk4f/src/interaction/ray_casting.jl:234 [inlined]
│      [8] show_data(inspector::DataInspector, plot::LineSegments{Tuple{Vector{Point{3, Float32}}}}, idx::Int64)
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/inspector.jl:518
│      [9] show_data_recursion(inspector::DataInspector, plot::LineSegments{Tuple{Vector{Point{3, Float32}}}}, idx::Int64)
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/inspector.jl:339
│     [10] on_hover(inspector::DataInspector)
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/inspector.jl:307
│     [11] (::Makie.var"#1236#1240"{DataInspector})(::Tuple{Float64, Float64})
│        @ Makie ~/.julia/packages/Makie/Qvk4f/src/interaction/inspector.jl:280
│     [12] #invokelatest#2
│        @ Base ./essentials.jl:887 [inlined]
│     [13] invokelatest
│        @ Base ./essentials.jl:884 [inlined]
│     [14] notify
│        @ Observables ~/.julia/packages/Observables/YdEbO/src/Observables.jl:206 [inlined]
│     [15] setindex!(observable::Observable, val::Any)
│        @ Observables ~/.julia/packages/Observables/YdEbO/src/Observables.jl:123
│     [16] (::WGLMakie.var"#58#60"{Dict{Any, Any}, Scene, Events})()
│        @ WGLMakie ~/.julia/packages/WGLMakie/t9g1u/src/events.jl:57
└ @ WGLMakie ~/.julia/packages/WGLMakie/t9g1u/src/events.jl:109

Two snapshots from WGLMakie backend shown below:

[SimonDanisch]

I think WGLMakie behaves correct now for this simpler example:

begin
    segments = Point2f[(0, 0), (0, 1), (1, 0), (1, 2)]
    color = [:red, :black, :blue, :black]
    inspector_label(_, i, _) = (@show Int(i); ["hello", "world", "nice", "day"][mod1(i, 4)])
    fig, ax, pl = linesegments(segments; color, inspector_label, linewidth=10)
    DataInspector(ax)
    display(fig; backend=WGLMakie)
end

It feels a bit buggy, that the index for the segment start only gets picked at the very beginning of the line, it should be more in the middle. Will need to look at the shader to see if we can fix that.

The out of bounds error you're getting sounds like you checked out the branch too early, I pushed a fix for that just before merging.

For GLMakie, it only gives indices for the ends of the line, not sure if we can change that right away.

[kbarros]

Thanks, I can confirm the bounds error is gone! To elaborate on the remaining bug, it seems to either "detect" the line itself, correctly (index 2) or some other object marking the beginning of the line, at the wrong position (index 1). Please see attached movie in the context of your 2D example.

2D_example.mov