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Board

When talking about math, it's hard to dodge function plots, when talking about results it's hard to dodge curves, so write them on a board!

show << Board::Add("fig", vec2(-M_PI, M_PI), vec2(-1.2, 1.2))->at("figure")
     << inNextFrame
     << Plot::Add("sine", "fig", [](scalar x){ return std::sin(x); })
     << Legend::Add("fig");
Primitive
Board the frame: background, data rectangle, grid, axes, tick labels. No data of its own
Plot one curve, drawn in the rectangle of the board it names
Scatter the measurements themselves, as marks
Legend what the curves of a board are called, in one of its corners

Each plot primitive is independent so you can make them appear and disappear when you want. You can edit each primitive shader to customize the look.

Adding one

c++ Board::Add(std::string name, optional<vec2> x, optional<vec2> y, int w = 1100, int h = 620);

A range given here is fixed; omitted, it is a tunable parameter. w and h are the render resolution of the frame.

A board is known by its name. Plot::Add("sine", "fig", f) takes the board or that name. Use setRange(x, y) to change the view.

What it publishes

Everything the board is made of is published under its name:

Setting Default
fig/xrange fig/yrange the data interval across and up (-1, 1)
fig/xscale fig/yscale linear or log linear
fig/xstep fig/ystep data units between ticks, 0 for round numbers from the range 0
fig/tick_font latex or text latex
fig/tick_size how big the tick labels are 0.4
fig/xticks which edge carries the labels: bottom top none bottom
fig/yticks left right none left
fig/show_grid fig/show_axes fig/show_frame the grid, the lines x = 0 and y = 0, the border true
fig/background fig/grid fig/axis the rectangle, the grid lines, the axes and labels white
fig/line_width pixels, the frame and axis weight 1.8

Latex ticks cost a compile per label, so a range that moves every frame wants tick_font: text.

Axis names and labels

For the sake of simplicity, you must add axis names by hand, as standard text. You may use label(primitive, at) to follow a point in the data space.

c++ Board::label(ScreenPrimitivePtr p, vec2 at, vec2 offset = vec2::Zero());

at is in data units, on a log axis too. offset is added afterwards in screen units, to clear the point itself.

show << fig->label(Formula::Add("\\varepsilon_{20}"), vec2(20, 1e-4), vec2(-0.03, 0));

The point is resolved every frame, so the label follows the view: setRange, or a snippet owning fig/xrange, moves it.

From a deck, follow: places anything at a point of the board:

- formula: \varepsilon_{20}
  follow: conv.last     # a snippet section returning a point of the board
  offset: [-0.05, 0]

Setting a value

Every name a board, a curve or a legend publishes is settable three ways, in this order of priority:
a snippet section of that name drives it, never a parameter
a deck key, or settings.set from C++ fixes it, never a parameter
neither a parameter, tunable in the Tuner and saved 
--- fig/xrange
-- the view, and its motion, owned by the snippet
return vec2(-3.15 + 3.75 * t:sinceKeyframe("zoom"), 3.15)

fig->settings.set("xticks", "right");   // fixed, gone from the Tuner

The legend

Legend::Add("fig") lists the curves and scatters of that board, in the order they were declared, each drawing its own swatch, under its caption or else its name. It publishes under fig_legend/:

Setting Default
fig_legend/corner top_left top_right bottom_left bottom_right top_right
fig_legend/text_size how big the captions are 0.4
fig_legend/swatch length of a swatch, in pixels 46
fig_legend/padding the space around and between 12
fig_legend/background fig_legend/border fig_legend/text the box, its edge, the captions

The shader is a file you edit

A board and a curve are shaders. The first time one is shown, its fragment program is written to views/<name>.glsl and drawn from there, hot-reloaded like any other. Open the file mid-talk and the figure changes as you save. Delete it and the default comes back.

The uniforms are bound already, named after the settings above. A board gets background, grid_color, axis_color, grid_step, axis_at (where x = 0 and y = 0 fall), line_width and show (grid, axes, frame), and draws in the board's data space, read as iWorld(). What a curve gets, and an example of editing one, is on the curves page.

Deck format

- board: fig            # the frame
  at: figure            # placement, defaults to the board's name
  resolution: [1100, 620]
  yrange: [-1.35, 1.35] # xrange left out: a parameter, or owned by a snippet
  tick_font: text       # any setting of the table above

- legend: fig           # the legend of the board "fig"
  corner: bottom_left

A plot and a scatter name their board with board:, or take the last one declared above them.