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author | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
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committer | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
commit | 67cdcc2e12118becb823e20a40cc2687f2b8425a (patch) | |
tree | ed92c3234b89079e6d4cf36f5e80c5ffa79def48 /meap/meap-code/ch6/ch6-particles/src | |
parent | e25482fca375d318a39c3b54db396b0db6e0b263 (diff) | |
download | learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.tar.xz learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.zip |
Started Rust in Action MEAP.
Diffstat (limited to 'meap/meap-code/ch6/ch6-particles/src')
-rw-r--r-- | meap/meap-code/ch6/ch6-particles/src/main.rs | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/meap/meap-code/ch6/ch6-particles/src/main.rs b/meap/meap-code/ch6/ch6-particles/src/main.rs new file mode 100644 index 0000000..93696fb --- /dev/null +++ b/meap/meap-code/ch6/ch6-particles/src/main.rs @@ -0,0 +1,170 @@ +// #![feature(alloc_system, global_allocator, allocator_api)] + +// extern crate alloc_system; + +// use alloc_system::System; + +// #[global_allocator] +// static A: System = System; + +extern crate graphics; +extern crate piston_window; +extern crate rand; + +use graphics::math::{ Vec2d, add, mul_scalar }; +use piston_window::{ PistonWindow, WindowSettings, clear, rectangle }; +use rand::distributions::{IndependentSample, Range}; + +type RGBA = [f32; 4]; +const WHITE: RGBA = [1.0; 4]; +const GRAY: RGBA = [0.7, 0.7, 0.7, 0.3]; +const N_PARTICLES: usize = 500; + +struct World { + current_turn: usize, + shapes: Vec<Box<Shape>>, + height: u32, + width: u32, +} + +struct Shape { + height: f64, + width: f64, + position: Vec2d<f64>, + velocity: Vec2d<f64>, + acceleration: Vec2d<f64>, + color: RGBA, +} + +impl Shape { + fn new(x: f64, y: f64) -> Self { + let mut rng = rand::thread_rng(); + let legal_range = Range::new(-5_f64, 5_f64); + + let x_speed = legal_range.ind_sample(&mut rng); + let y_speed = legal_range.ind_sample(&mut rng); + let x_accel = 0.1 * legal_range.ind_sample(&mut rng); + let y_accel = 0.1 * legal_range.ind_sample(&mut rng); + + Shape { + height: 10.0, + width: 10.0, + position: [x, y], + velocity: [x_speed, y_speed], + acceleration: [x_accel, y_accel], + color: GRAY, + } + } + + fn update(&mut self) { + self.velocity = add(self.velocity, self.acceleration); // <> There is no matrix/vector math operators within the language. `graphics::math` is providing this functionality for us. + self.position = add(self.position, self.velocity); + self.acceleration = mul_scalar(self.acceleration, 0.7); // <> Slow down the shape's movement + self.color[3] *= 0.97; + } +} + +impl World { + fn new(width: u32, height: u32) -> World { + World { + current_turn: 0, + shapes: Vec::<Box<Shape>>::new(), + height: height, + width: width, + } + } + + fn add_shapes(&mut self, n: usize) { + let x = (self.width / 2) as f64; + let y = (self.height / 2) as f64; + + for _ in 0..n { + self.shapes.push(Box::new(Shape::new(x, y))); + }; + } + + fn remove_shapes(&mut self, n: usize) { + let n_shapes = self.shapes.len(); + + let to_remove = if n > n_shapes { + n_shapes + } else { + n + }; + // let to_remove = cmp::min(n as usize, self.shapes.len()); + + for _ in 0..to_remove { + self.shapes.remove(0); // Remove the oldest particle. This is quite an inefficient operation, as all remaining particles are shifted to fill the now-empty slot. A smarter strategy would be to use `std::collections::VecDeque`, which supports removing from the front. + } + + self.shapes.shrink_to_fit(); // Will help to force a re-allocation later when shapes are added. + } + + fn calc_population_change(&self) -> isize { + const N: f64 = N_PARTICLES as f64; // <> Shorter alias + const MAX: f64 = N*0.5; + const MIN: f64 = -N*0.5; + let x: f64 = self.current_turn as f64; + + //let n: f64 = N_PARTICLES; + let n = 0.4*N*(0.1*x).sin() + 0.1*N*x.sin(); + n.max(MIN).min(MAX).round() as isize // limit range of growth/death then convert to `isize` + } + + fn update(&mut self) { + let n = self.calc_population_change(); + //let n = as usize; // <> Convert f64 to usize + + if n > 0 { + self.add_shapes(n as usize); + } else { + self.remove_shapes(n.abs() as usize); + } + + self.current_turn += 1; + } +} + +// impl Iterator for World { +// type Item = isize; + +// fn next(&mut self) -> Option<isize> { +// let x = self.current_turn; + +// // 30sin(x) + 10sin(0.1x) + 20sin(0.2x) + 30sin(0.3x) + 40sin(0.4x) + 50sin(0.5x) +// let y = 50.0*(0.1*x).sin() + 30.0*x.sin(); +// self.current_turn += 1.0; +// Some(y.round() as isize) +// } +// } + +fn main() { + let (width, height) = (640, 480); + let mut window: PistonWindow = + WindowSettings::new("particles", [width, height]) + .exit_on_esc(true) + .build() + .expect("Could not create a window."); + + // Initialize + let mut world = World::new(width, height); + world.add_shapes(N_PARTICLES); + + while let Some(event) = window.next() { // main loop + // Update Step + for shape in &mut world.shapes { + shape.update(); + } + world.update(); + + // Render Step + window.draw_2d(&event, |ctx, renderer| { + clear(WHITE, renderer); + for s in &mut world.shapes { + let rect = [s.position[0], s.position[1], s.width, s.height]; + let transformation_matrix = ctx.transform; + rectangle(s.color, rect, transformation_matrix, renderer); // create a graphics::Rectangle and call draw() on it + } + }); + } +} |