Circle Boundary

A single purpose library. This library's aim is to return a circle boundary as represented in discrete pixels as shown in the following diagram.

Usage

Include the library into your application with the following line at the top of your main file.

extern crate circle_boundary;

And then get access to the public calculate function by adding the following line at the top of the file you want to use it in.

use circle_boundary::calculate;
use circle_boundary::Boundary;

Then you can use the calculate function to get a vector of boundary data structures back. Each boundary structure holds a pair of cartesian coordinates (x and y) where x is represented by a single number indicating it's position, and y is represented by a range to show where on the y-axis the boundary applies.

The calculate function expects the origin as represented by the first two arguments, a x value as an i32 integer and a y value as an i32 integer. The final argument is the radius of the circle you want a boundary for as represented as a i32 integer.

let bounds = calculate(0, 0, 3);

As noted above the value returned is a vector that represents the boundary as such:

vec![
    Boundary { x: -3,  y: -1..1 },
    Boundary { x: -2,  y: -2..2 },
    Boundary { x: -1,  y: -3..3 },
    Boundary { x:  0,  y: -3..3 },
    Boundary { x:  1,  y: -3..3 },
    Boundary { x:  2,  y: -2..2 },
    Boundary { x:  3,  y: -1..1 },
];

Which could be represented as in the following diagram. Where the dark grey square represents the origin, the green squares represent the lower bounds of the y range, and the red squares represent the upper bounds of the y range.

Off origin example

As noted the calculate function can be given coordinates that offset the results from a (0,0) origin. If you pass in an offset like:

calculate(9, 3, 7);

This returns the following vector:

vec![
    Boundary { x: 2, y: 1..5 },
    Boundary { x: 3, y: -1..7 },
    Boundary { x: 4, y: -2..8 },
    Boundary { x: 5, y: -3..9 },
    Boundary { x: 6, y: -3..9 },
    Boundary { x: 7, y: -4..10 },
    Boundary { x: 8, y: -4..10 },
    Boundary { x: 9, y: -4..10 },
    Boundary { x: 10, y: -4..10 },
    Boundary { x: 11, y: -4..10 },
    Boundary { x: 12, y: -3..9 },
    Boundary { x: 13, y: -3..9 },
    Boundary { x: 14, y: -2..8 },
    Boundary { x: 15, y: -1..7 },
    Boundary { x: 16, y: 1..5 },
];

Which represents the following circle boundary where the black square represents the (0,0) origin:

Examples

For more examples on how to use this library you can look in the examples/ folder in this repository. You can run each one with the following command:

cargo run --example <example-name>

For example:

cargo run --example introduction

Would run the introductory example file examples/introduction.rs.

Development

Building for Rust

Have Rust and Cargo installed, then run:

cargo build

Building for the Web

Install wasm-pack, then run:

wasm-pack build

• Copy over the README_NPM.md file into the /pkg folder as README.md.
• Make sure the images file is copied over into the generated /pkg folder as well.

Runing the tests

Use the Cargo command:

cargo test