TERMINAL ART

1. THE SHAPE OF A PROGRAM

Every program is a main that ends by showing one thing: a sketch (a formula for every cell) or a world (balls that move).

use terminal_graphics_interactive::prelude::*;

fn main() -> std::io::Result<()> {
    sketch(|cell| (cell.x * 0.2 + cell.t).sin())
}

2. A SKETCH: ONE FORMULA FOR EVERY CELL

The formula runs for every cell, every frame. It gets a cell and returns a number from -1.0 to 1.0 (what sin and cos give), which the palette turns into a colour.

cell.x

which column this cell is in

cell.y

which row, stretched so one step looks as long as one step of x

cell.t

seconds since you pressed RUN

cell.mouse_x

the column the mouse is over

cell.mouse_y

the row the mouse is over, stretched like y

cell.mouse_down

true while the left button is held

cell.width

how wide the screen is

cell.height

how tall the screen is, stretched like y

cell.dist_to_mouse()

how far this cell is from the mouse

Use sketch(|cell| ...) for the ocean palette, or sketch_with(palette, |cell| ...) to choose.

3. PALETTES AND COLOURS

Presets: ocean fire rainbow mono used as Palette::fire().

Or make your own, dark to bright: Palette::new(&[Colour::Black, Colour::Red, Colour::BrightYellow]).

Colours: Black Red Green Yellow Blue Magenta Cyan White BrightBlack BrightRed BrightGreen BrightYellow BrightBlue BrightMagenta BrightCyan BrightWhite

4. MATHS

On any decimal (f32), like cell.x.sin():

sin cos tan asin acos atan sinh cosh tanh sqrt cbrt abs floor ceil round trunc fract signum exp ln log10 log2 recip to_radians to_degrees

With one argument, like a.min(b) or a.powf(2.0):

powf atan2 min max hypot rem_euclid copysign

Also a.powi(3) (a whole-number power), a.clamp(low, high) and a.mul_add(b, c).

Constants: PI TAU E FRAC_PI_2 FRAC_PI_3 FRAC_PI_4 FRAC_PI_6 SQRT_2 LN_2 LN_10 (as PI, or std::f32::consts::PI).

5. A WORLD: BALLS THAT MOVE

Chain settings and finish with .run(). Balls bounce off the walls and each other, and a click adds one.

World::new()
    .balls(5)
    .size(3.5)
    .gravity(0.02)
    .mouse_pulls()
    .trails()
    .run()

.balls(...)

how many balls to start with (a whole number, up to 64)

.size(...)

how big each ball is, as a radius: try 3.5

.gravity(...)

a pull downwards each frame: try 0.02, or a negative number to float up

.mouse_pulls()

the mouse pulls the balls in; hold the right button to push them away

.trails()

balls leave glowing tails

.palette(...)

the colours the balls are drawn in

.run()

end the chain with this

6. THE RUST RULES (THIS EDITOR IS AS STRICT AS THE REAL COMPILER)

Decimals need a dot: cell.x * 2.0 works, cell.x * 2 does not. Whole numbers are for counts and loops.

let speed = 2.0;              // a decimal
let mut total = 0.0;
for i in 0..5 {               // i is a whole number
    total += (i as f32) * 0.1;  // turn it into a decimal with `as f32`
}
if cell.mouse_down { total } else { -total }

You can use let, let mut, if / else, for i in 0..5, and your own functions like fn ring(d: f32) -> f32. Press RUN and the compiler tells you the line and column of any mistake.

7. TAKE IT HOME

This is real Rust. Anything that runs here also compiles in your own project:

$ cargo add terminal_graphics_interactive
$ cargo run

Paste your code into src/main.rs and it runs in your own terminal (Windows PowerShell, Linux, macOS), with your real mouse. Use SHARE to send your art to a friend as a link.