marching-squares

This crate provides an (optionally parallelizable) marching squares algorithm to generate isolines from a heightmap of Vec<Vec<i16>> values.

Adapted from https://github.com/d-dorazio/marching-squares

Warning

• The returned lines may only have two points.

Example

```rust use marching_squares::{Field, Point};

fn main() {

let width = 1600_usize;
let height = 1600_usize;

let n_steps = 10_usize;
let mut min_val = 0;
let mut max_val = 0;

// Build the heightmap data (here: randomly generated from a function)
let z_values = (0..height).map(|y| {
    (0..width).map(|x| {
        let x = (x as f64 - width as f64 / 2.0) / 150.0;
        let y = (y as f64 - height as f64 / 2.0) / 150.0;
        let val = ((1.3 * x).sin() * (0.9 * y).cos() + (0.8 * x).cos() * (1.9 * y).sin() + (y * 0.2 * x).cos()) as i16;
        min_val = min_val.min(val);
        max_val = max_val.max(val);
        val
    }).collect()
}).collect::<Vec<Vec<i16>>>();

let field = Field {
    dimensions: (width, height),
    top_left: Point { x: 0.0, y: 0.0 },
    pixel_size: (1.0, 1.0),
    values: &z_values,
};

let step_size = (max_val - min_val) as f32 / n_steps as f32;

// Generate 10 isolines
// note: you could do this in parallel using rayon
for step in 0..n_steps {
    let isoline_height = min_val as f32 + (step_size * step as f32);
    println!("{:#?}", field.get_contours(isoline_height as i16));
}

} ```

License: MIT