Plots in Odin Bare Minimum

A very simple but useful plots lib for the Odin programming language.

Description

A tiny, dependency-light 2D plotting library written in Odin. It is a bare-minimum software renderer that draws directly into an RGBA pixel buffer and saves the result to disk as PNG or JPG via vendor:stb/image.

No external GUI, no fonts, no SVG, no GPU — everything ( lines, ticks, grid, axes, legend, colour-bar, text ) is drawn by hand into pixels with an embedded 5×7 bitmap font.

Features

Plot types: line / scatter (Standard), heatmap with colour-bar (Elevation), and Histogram.
Multiple traces per standard plot with auto-assigned colours from DEFAULT_PALETTE.
Real axes: nice rounded tick steps, gridlines, four-quadrant support, optional zero-axes through the origin, X / Y axis labels ( Y is rendered vertically) and an automatic textual legend with colour swatches.
Auto-computed margins from the actual content (title, labels, legend width, plot type) — or override with set_margins.
Text scaling 1× / 2× / 3× for hi-DPI / 4K monitors (set_text_scale).
Themes: Light, Dark, or Custom.
Output: PNG (save_png) or JPG (save_jpg).

Build & run the demos

make            # odin build . -out:plots_test.exe -o:speed
./plots_test.exe

This produces the four images shown below.

Gallery

Standard plot (line + scatter, light theme, text scale 1)

Four-quadrant plot (dark theme, text scale 3)

Histogram (normal samples via `rand.norm_float64`, text scale 2)

Elevation (heatmap + colour-bar)

Quick example

package main

import plt "plots_bare_minimum"

main :: proc( ) {
	
    plot, _ := plt.create_plot( 1280, 800, .Light )
    defer plt.destroy_plot( & plot )

    plt.set_title( & plot, "sin(x)" )
    plt.set_axis_labels( & plot, "x", "y" )

    xs := plt.linearspace( -6.28, 6.28, 400 )
    defer delete( xs )
    ys := make( [ ]f64, len( xs ) )
    defer delete( ys )
    for x, i in xs do ys[ i ] = math.sin( x )

    plt.add_trace_auto( & plot, "sin", xs, ys, .Line )
    plt.save_png( & plot, "sin.png" )
}

Public API

Types & constants

Name	Description
`Plot`	The plot state (canvas, traces, margins, theme, ...).
`Plot_Error`	Error enum returned by most procs.
`Theme_Mode`	`.Light`, `.Dark`, `.Custom`.
`Theme`	Colour set used by a plot (background, axis, grid, text, …).
`Color`	`[4]u8` — RGBA.
`Marker_Type`	`.Line`, `.Dot`, `.Cross`, `.Both`.
`Plot_Type`	`.Standard`, `.Elevation`, `.Histogram` (set automatically).
`DEFAULT_PALETTE`	Built-in colour cycle used by `add_trace_auto`.

Lifecycle

Proc	Description
`create_plot( width, height, mode := .Dark ) -> ( Plot, Plot_Error )`	Allocate a new plot canvas.
`destroy_plot( plot: ^Plot )`	Free the plot and any owned data ( histogram bins, etc. ).

Configuration

Proc	Description
`set_title( plot, title )`	Plot title (drawn at fixed text scale 2).
`set_axis_labels( plot, x_label, y_label )`	Axis legends; Y label is rendered vertically.
`set_x_range( plot, min_x, max_x )`	Manual X range ( otherwise auto-scaled from data ).
`set_y_range( plot, min_y, max_y )`	Manual Y range.
`set_margins( plot, left, right, top, bottom )`	Manual margins ( disables auto-margins ).
`set_text_scale( plot, scale )`	Text size for ticks/labels/legend: 1, 2 or 3 ( clamped ). Title stays at 2.
`set_show_grid( plot, on )`	Show/hide the grid lines.
`set_show_legend( plot, on )`	Show/hide the legend box.
`set_show_zero_axes( plot, on )`	Show/hide the X=0 / Y=0 axes through the origin.

Data

Proc	Description
`linearspace( start, stop, n ) -> []f64`	NumPy-style evenly spaced points ( caller owns the slice ).
`add_trace( plot, name, x, y, color, marker := .Line ) -> Plot_Error`	Add a trace with an explicit colour.
`add_trace_auto( plot, name, x, y, marker := .Line ) -> Plot_Error`	Add a trace and pick the next palette colour.
`add_histogram( plot, name, data, num_bins, color ) -> Plot_Error`	Compute bins and add a histogram ( honours `set_x_range` ).
`add_elevation( plot, z_data, grid_w, grid_h ) -> Plot_Error`	Heatmap data, row-major `grid_w * grid_h` values.

Output

Proc	Description
`save_png( plot, filename ) -> Plot_Error`	Render and write a PNG.
`save_jpg( plot, filename , quality := 90 ) -> Plot_Error`	Render and write a JPG.

Project layout

.
├── main.odin                       # Demos that produce the 4 images above
├── plots_bare_minimum/
│   └── plots_bare_minimum.odin     # The library
├── Makefile                        # `make`, `make run`, `make clean`
└── README.md

License

MIT open source license

Have fun

Best regards,
Joao Carvalho