llandau

Smooth scientific slides, drawn live. Decks are written like manim scenes (with manim-slides' steps), but nothing is rendered ahead: every animation is drawn as it plays (wgpu), so there are no videos, no render step and no Qt. Built for presenting riemann: interactive 3D views of atomic trajectories, splines, tangents and proteins sit inside the slides, and plots come straight from numpy arrays.

from llandau import *

class Results(Deck):
    theme = LIGHT
    def construct(self):
        self.title("sampling a double well")
        energy = self.reveal(image("figures/energy.png", R.body.left))
        self.reveal(below(text("$p(x) prop e^(-U(x) \/ k T)$"), energy), anim=Write)
        self.show_svg("figures/sketch.svg", R.body.right)   # one slide step per Inkscape layer

SLIDES = order(Results)

The figures above are placeholders; examples/slides.py is the same deck with plots drawn from numpy, runnable as is.

llandau play slides.py              # present: arrows step, F full screen, the wheel scrubs
llandau play slides.py --only Results --start 3
llandau pdf slides.py               # one page per step
llandau png slides.py OUT_DIR

Install

Wheels for macOS and Linux (Python >= 3.10) are on PyPI (llandau, after Lev Landau):

pip install llandau

or build it (needs Rust): pip install maturin && maturin develop --release (MACOSX_DEPLOYMENT_TARGET=15.0 on macOS).

External tools:

• typst CLI: all text and math
• rsvg-convert (librsvg) or Inkscape: rasterizing layered SVGs (or pip install cairosvg)
• fonts: Linux Biolinum O (text), Libertinus Math (math; falls back to New Computer Modern Math)
• optional: pillow (llandau pdf | png), matplotlib (its colormaps), contourpy (contour plots), ffmpeg (videos: the explorer's record button; pip install 'llandau[video]' brings one)

Slides

Animations follow manim's definitions (timing, lag, rate functions); those without a native clip (rotations, path_arc, updaters, custom interpolate_mobject) are stepped at 60 fps when the deck is built. A deck is one timeline of clips; the player evaluates it at any time, so playing, stepping back and scrubbing (the wheel) are the same thing.

Plots

ax = Plot(R.body.right, xlabel="time $t$ (ps)", ylabel="energy (eV)")
md = ax.plot(t, e, label="MD")                       # nothing shown yet
with ax.group() as samples:                          # several commands, one step
    ax.scatter(ts, es, c=w, cmap="viridis", s=30, label="samples")
    ax.fill_between(t, lo, hi, alpha=0.2)
legend = ax.legend()

self.reveal(ax)                                      # frame, ticks and labels first
self.reveal(md, anim=Create)                         # the line draws itself
self.reveal(samples, legend, anim=FadeIn)

plot scatter fill_between axhline axvline bar hist errorbar imshow contour contourf text legend colorbar, with matplotlib's arguments; sizes in points (times scale=2). ax.c2p(x, y) places other mobjects at data coordinates.

Figures for papers

The same plots, saved as files, in print sizes (inches and points) and the thesis matplotlibrc style:

from llandau import subplots

fig, ax = subplots(figsize=(3.0, 2.0))                    # inches
ax.plot(lam, exact, color="k", label="exact")
ax.plot(lam, ode, color="#b8b8b8", label="ODE ($A -> B$)")
ax.scatter(lam[i], ode[i], s=20, color=CB0, zorder=50)
ax.set_xlabel("$lambda_(A -> B)$ [-]")                   # math in Typst syntax
ax.set_xlim([-1.0, 1.0])
ax.legend(bbox_to_anchor=(0.5, 1.0))
fig.savefig("ode.svg")                                    # vector; also .pdf, .png (dpi=)

SVG and PDF are vector, with text as outlines (it looks the same in any document); bbox_inches="tight" and a transparent background are the defaults. fig.show() opens a window. subplots(2, 3) gives an array of plots; fig.add(mobject) puts anything else on the figure; place(fig, R.body, fit="fill") puts a finished figure on a slide. matplotlib's setters work (set_xlabel set_ylabel set_title set_xlim set_ylim set_xscale set_xticks set_aspect grid), as do zorder, colorbar(..., format="%.1f", labelpad=12) and colors like "k", "C0". Math is Typst's: $\lambda_{A\rightarrow B}$ becomes $lambda_(A -> B)$. See examples/paper_figures.py.

Live 3D steps

@live_scene("butane")
def butane(viewer):                          # a llandau.Viewer, in the deck's theme
    viewer.load(positions, numbers)          # (frames, atoms, 3), (atoms,)

class Results(Deck):
    def construct(self):
        self.live("butane", R.body.right)    # the next step shows it over R.body.right
        self.reveal(place(text("3D here"), R.body.left))
        self.live("butane", R.body.right, camera={"azimuth": 30}, frame=60)  # moves there
        self.reveal(...)

Over a live view: drag rotates, right drag pans, the wheel scrubs frames, pinch zooms; , . step frames, P plays, D toggles the discrete states, 0 resets the camera. Exports show a still image of each live view. See llandau.live for the view settings.

Layer conventions for show_svg: steps are ordered by the first number in each Inkscape layer label (layers sharing a number appear together), saved visibility is ignored, and layers whose label starts with _ are skipped.

The viewer

from llandau import Viewer, segment_ids
from llandau.explorer import explore

viewer = Viewer(theme="light").load(positions, numbers, roles=roles)   # (frames, atoms, 3), (atoms,)
viewer.style = "protein"                      # or "atoms" (ball and stick)
viewer.sidechains = "spheres"                 # van der Waals spheres; or "sticks"
viewer.shading = "flat"                       # plain colors with a dark outline (cinemol-like); or "lit"
viewer.set_visible("surface", True)           # translucent molecular surface around the heavy atoms
viewer.set_surface(opacity=0.4, colors="uniform", sharpness=2.0)   # colors="atoms": nearest atom's color
viewer.set_visible("clashes", True)           # vdW overlap > viewer.clash_overlap (Å), beyond 3 bonds
viewer.set_trails(segment_ids=segment_ids(t, spline.segment_boundaries))
viewer.add_vectors("tangent", tangents, scale=1.5)
viewer.color_by("kinetic energy", per_atom_values, cmap="fire")   # then viewer.coloring = "kinetic energy"
viewer.set_ghost(target_positions)            # translucent, in the same style
viewer.set_discrete_frames(states)            # (states, atoms, 3): same atoms, e.g. the discrete trajectory
viewer.scrub_discrete = True                  # `frame` now walks those states instead of the path
viewer.frame = 30
image = viewer.render_image(800, 600)         # (600, 800, 4) uint8
explore(viewer, plots={"action": action}, t=t)

Roles (as riemann's atom_role): 0 hydrogen, 1 side chain heavy atom, 2 backbone N C O, 3 CA. The protein style draws a smooth tube through the CAs and the side chains, no hydrogens; trails follow the CAs only. Themes ("light", "dark") set the background and every non-element color; element colors come from llandau.elements.

explore(viewer, plots=..., t=...) opens a native window (winit + egui) with the 3D view, a panel of controls and plots; it works on macOS, X11 and Wayland. Keys: space plays, , . step frames, D toggles the discrete states, 0 resets the camera, R records, Escape closes. Recording keeps what you do in the 3D view; stopping renders it offscreen into an MP4 (H.264) at a fixed frame rate, without the panel: explore(viewer, record="turn.mp4", record_size=(1920, 1080), record_fps=60), or any frames with llandau.video.Video. Without a GPU, a software Vulkan driver (Mesa's lavapipe) works; WGPU_BACKEND=vulkan|gl|metal picks the backend, Viewer().adapter tells which GPU is in use.

python examples/explore_butane.py                     # explorer window
python examples/explore_trpcage.py 1l2y.pdb           # protein: NMR models as frames
python examples/render_layers.py OUT_DIR 1l2y.pdb     # offscreen PNG of each feature
llandau play examples/live_demo.py                     # a deck with live 3D steps

Layout

• src/slides/: decks: timeline (clips, marks, manim's animation logic), paint (lyon tessellation, supersampled wgpu drawing), svg (usvg), player (the window), live (3D views in decks)
• src/: the viewer: camera (z-up turntable), scene (structure and layers -> instances), protein, surface, clash, theme, render (sphere impostors, instanced lathe meshes, two-pass ghost, overlay), window (the explorer), lib (Python bindings)
• python/llandau/: the Python side of both