Raster bars: Difference between revisions

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 (Small) Moving gif of swaying bars: [https://github.com/thundergnat/rc/blob/master/img/Raster-bars-swaying-Raku.gif (offsite .gif image)]
+=={{header|Rust}}==
+<lang rust>
+extern crate minifb;
+use std::iter::repeat;
+use minifb::{Key, Window, WindowOptions};
+const WIDTH: usize = 640;
+const HEIGHT: usize = 360;
+struct Bar {
+    color: [f32; 3],
+    height: u32,
+    position: f32,
+    speed: f32,
+}
+impl Bar {
+    fn draw_column(&self, column_buffer: &mut [u32]) {
+        let start_row = (self.position.round() as i32).clamp(0, HEIGHT as i32) as usize;
+        let end_row = (start_row + self.height as usize).clamp(0, HEIGHT);
+        column_buffer[start_row..end_row].iter_mut().enumerate()
+            .for_each(|(row_index, color)| {
+                *color = self.row_color(row_index as i32);
+            });
+    }
+    fn row_color(&self, y: i32) -> u32 {
+        let yy = y as f32 / (self.height - 1) as f32;
+        let yy = 1.0 - 2.0 * (yy - 0.5).abs();
+        let r = (25.0 + yy.powf((2.0 - 2.0 * self.color[0]).exp()) * 230.0).round() as u8;
+        let g = (25.0 + yy.powf((2.0 - 2.0 * self.color[1]).exp()) * 230.0).round() as u8;
+        let b = (25.0 + yy.powf((2.0 - 2.0 * self.color[2]).exp()) * 230.0).round() as u8;
+        u32::from_be_bytes([255, r, g, b])
+    }
+    fn update_position(&mut self) {
+        self.position += self.speed;
+        if let Some(position) = self.bounce_position() {
+            self.position = position;
+            self.speed = -self.speed;
+        }
+    }
+    fn bounce_position(&self) -> Option<f32> {
+        if self.speed > 0.0 {
+            let limit = (HEIGHT as i32 - self.height as i32) as f32;
+            (self.position >= limit).then(|| limit - (self.position - limit))
+        } else {
+            (self.position <= 0.0).then(|| -self.position)
+        }
+    }
+}
+fn main() {
+    let mut window = Window::new(
+        "Raster Bars",
+        WIDTH,
+        HEIGHT,
+        WindowOptions::default(),
+    )
+    .unwrap_or_else(|e| {
+        panic!("{}", e);
+    });
+    // Limit to max ~60 fps update rate
+    window.limit_update_rate(Some(std::time::Duration::from_micros(16600)));
+    let mut bars = Vec::new();
+    bars.push(Bar { color: [1.0, 1.0, 0.0], height: 20, position: 0.0, speed: 3.1 });
+    bars.push(Bar { color: [1.0, 0.0, 0.0], height: 25, position: 0.0, speed: 0.2 });
+    bars.push(Bar { color: [0.0, 1.0, 0.0], height: 7, position: 0.0, speed: 0.4 });
+    bars.push(Bar { color: [0.0, 0.0, 1.0], height: 30, position: 0.0, speed: 1.0 });
+    while window.is_open() && !window.is_key_down(Key::Escape) {
+        let mut column_buffer = vec![0x_00_00_00_u32; HEIGHT];
+        for bar in &mut bars {
+            bar.draw_column(&mut column_buffer);
+            bar.update_position();
+        }
+        let buffer: Vec<u32> = column_buffer.iter()
+            .flat_map(|&row_color| repeat(row_color).take(WIDTH))
+            .collect();
+        window
+            .update_with_buffer(&buffer, WIDTH, HEIGHT)
+            .unwrap();
+    }
+}
+</lang>
 =={{header|Wren}}==