noisy_bevy 0.13.0

//! Shows how to sample noise on the CPU.
//!
//! Generates a simple fbm island height map on the CPU and spawns tiles
//! with corresponding colors.

use bevy::{camera::ScalingMode, math::vec2, prelude::*};
use bevy_pancam::{PanCam, PanCamPlugin};
use noisy_bevy::fbm_simplex_2d;

fn main() {
    App::new()
        .insert_resource(ClearColor(Color::BLACK))
        .add_plugins((DefaultPlugins, PanCamPlugin))
        .add_systems(Startup, setup)
        .run();
}

fn setup(mut commands: Commands) {
    commands.spawn((
        Camera2d,
        Projection::Orthographic(OrthographicProjection {
            scaling_mode: ScalingMode::FixedVertical {
                viewport_height: 70.0,
            },
            ..OrthographicProjection::default_2d()
        }),
        PanCam::default(),
    ));

    const FREQUENCY_SCALE: f32 = 0.05;
    const AMPLITUDE_SCALE: f32 = 4.0;
    const RADIUS: f32 = 30.;
    const OCTAVES: usize = 3;
    const LACUNARITY: f32 = 2.;
    const GAIN: f32 = 0.5;

    let grid_half_size = RADIUS as i32 + 1;

    for x in -grid_half_size..=grid_half_size {
        for y in -grid_half_size..=grid_half_size {
            let p = vec2(x as f32, y as f32);

            // this is the whole point of the example
            let offset =
                fbm_simplex_2d(p * FREQUENCY_SCALE, OCTAVES, LACUNARITY, GAIN) * AMPLITUDE_SCALE;

            let height = RADIUS + offset - ((x * x + y * y) as f32).sqrt();

            // spawn a corresponding tile with a color thats more white the higher the height
            commands.spawn((
                Sprite {
                    color: Color::WHITE.with_luminance(height * 0.03),
                    custom_size: Some(Vec2::splat(1.)),
                    ..default()
                },
                Transform::from_translation(Vec3::new(x as f32, y as f32, 100.)),
            ));
        }
    }
}