Documentation on `Zoom!`

[SimonCoste]

Hello, I am trying to use the zoom! function, see here, but there is no usable doc and no examples.

More generally, the doc is extremely hard to use: there are many functions who use Vec3f0, but I found no reference for this. For instance, zoom(scene, Vec3f0(0,0,0), 2) outputs a

no method matching zoom!(::Scene, ::Vec{3, Float32}, ::Int64)

so that I have no clue on how to use these Vec3f0 objects.

I also have no clues on what are those 5f0 often found in examples, and I could not find something in the doc on them.

Related : https://discourse.julialang.org/t/zoom-in-glmakie-3d-plot-then-save/65745

[ffreyer]

5f0 is a way to construct Float32, equivalent to Float32(5 * 10^0). Vec3f0 is just a (static) vector of 3 Float32's.

The function zoom!(scene, point, zoom_step, shift_lookat::Bool) applies to the old 3D camera, which is not used by default anymore. The arguments here are the scene it applies to (i.e. lscene.scene), the point which the zoom focuses, the amount of zooming that's done is zoom_step and shift_lookat = true adds translation when zooming to keep point at the same position.

The new camera has a method zoom!(scene, zoom_step) which does an fov based zoom where zoom_step again controls the amount of zooming. Depending on what kind of zoom you want. Here you need to call update_cam!(scene, cameracontrols(scene)) to apply the changes at the moment.

If you don't want an fov-based zoom you may want to try translating the camera instead. You can use translate_cam!(scene, Vec3f0(0, 0, +-zoom)) to translate in/out of the screen. (Again with a update_cam! afterwards) The Vec3f0 passed here is in camera space, so it's (left/right, up/down, in/out).

Another option is to adjust the camera position (eyeposition) and/or focal point (lookat) via update_cam!(scene, cameracontrols(scene), eyeposition, lookat).

This all only applies to 3D LScene's. If you're using a 2D Axis you should set xlims!(ax, low, high) and ylims!(ax, low, high) to zoom. Axis3 doesn't have a direct way to zoom available as far as I know.

[bvrb]

The new camera has a method zoom!(scene, zoom_step) which does an fov based zoom where zoom_step again controls the amount of zooming. Depending on what kind of zoom you want. Here you need to call update_cam!(scene, cameracontrols(scene)) to apply the changes at the moment.

I just tried this and can confirm it doesn't work for me either, in fact the plot disappears altogether after updating the camera as you described. However, zoom!(scene, cameracontrols(scene), zoom_step) followed by update_cam!(scene, cameracontrols(scene)) works correctly.

Is it possible that there is a typo on this line https://github.com/JuliaPlots/Makie.jl/blob/27fdbd6e5d1141e1e4456c9b008776825f3818c8/src/camera/camera3d.jl#L495 ? It seems that the zoom_step argument is never passed along to the zoom! method on the right hand side of the assignment, but instead gets set to false.

[SimonCoste]

Thanks to both of you for your answers ! 
On my side, your proposals did not work. The code

using GLMakie
let
    U = LinRange(-pi, pi, 100) # 50
    V = LinRange(-pi, pi, 20)
    x1 = [cos(u) + .5 * cos(u) * cos(v)      for u in U, v in V]
    y1 = [sin(u) + .5 * sin(u) * cos(v)      for u in U, v in V]
    z1 = [.5 * sin(v)                        for u in U, v in V]
    x2 = [1 + cos(u) + .5 * cos(u) * cos(v)  for u in U, v in V]
    y2 = [.5 * sin(v)                        for u in U, v in V]
    z2 = [sin(u) + .5 * sin(u) * cos(v)      for u in U, v in V]
    fig = Figure(resolution =(900,600))
    ax = LScene(fig, scenekw = (camera = cam3d!, show_axis = true))
    wireframe!(ax.scene, x1,y1,z1, shading = false)
    zoom!(ax.scene, cameracontrols(ax.scene), 3)
    update_cam!(ax.scene, cameracontrols(ax.scene))
    fig[1,1] = ax
end

does not result in a zoomed picture, with or without the cameracontrols(ax.scene).

Replacing the zoom! line with translate_cam!(scene, Vec3f0(0, 0, 3)) does not yield any difference either.

[ffreyer]

It seems that the zoom_step argument is never passed along to the zoom! method on the right hand side of the assignment, but instead gets set to false.

Oh yea, that's a typo.

On my side, your proposals did not work. The code ... does not result in a zoomed picture, with or without the cameracontrols(ax.scene).

I think Makie enters things everything when the plot is first displayed. You can try reordering some things and displaying first

fig = Figure(resolution =(900,600))
ax = LScene(fig, scenekw = (camera = cam3d!, show_axis = true))
wireframe!(ax.scene, x1,y1,z1, shading = false)
fig[1,1] = ax
display(fig)
zoom!(ax.scene, cameracontrols(ax.scene), 3)
update_cam!(ax.scene, cameracontrols(ax.scene))

or manually centering

ax = LScene(fig, scenekw = (camera = cam3d!, show_axis = true, center = false))
wireframe!(ax.scene, x1,y1,z1, shading = false)
center!(ax.scene)
zoom!(ax.scene, cameracontrols(ax.scene), 3)
update_cam!(ax.scene, cameracontrols(ax.scene))