Improves aquarium performance and appearance

Adjusts the simulation to use a fixed timestep and scales movement based on that timestep. This decouples the simulation speed from the rendering framerate.

Increases the default frame duration and provides UI elements to control the render cadence.

Reduces fish velocity to complement the fixed timestep, maintaining a visually appealing speed.

Author: gitcoder89431

examples/egui_demo.rs

@@ -20,6 +20,7 @@ struct MyApp {
     assets: Vec<asciiquarium_rust::FishArt>,
     state: AquariumState,
     theme: AsciiquariumTheme,
+    // Controls repaint cadence (ms). Simulation uses an internal dt; higher values reduce CPU and may not linearly affect perceived speed.
     frame_ms: u64,
     bg_enabled: bool,
 }
@@ -52,7 +53,7 @@ impl MyApp {
             assets,
             state,
             theme,
-            frame_ms: 33,
+            frame_ms: 50,
             bg_enabled: true,
         }
     }
@@ -84,6 +85,8 @@ impl eframe::App for MyApp {
                 ui.separator();
 
                 ui.label("Frame (ms):");
+                ui.label(format!("{} ms", self.frame_ms));
+                ui.small("Render cadence; simulation uses fixed dt ~33ms");
                 if ui.button("-").clicked() && self.frame_ms > 5 {
                     self.frame_ms -= 2;
                 }
@@ -156,13 +159,13 @@ fn spawn_random_fish(state: &mut AquariumState, asset_count: usize) {
     let y = rng.gen_range(0..=max_y) as f32;
 
     // Random velocity with minimum magnitude to avoid stationary fish
-    let mut vx = rng.gen_range(-0.5_f32..=0.5_f32);
-    let mut vy = rng.gen_range(-0.25_f32..=0.25_f32);
-    if vx.abs() < 0.05 {
-        vx = if vx.is_sign_negative() { -0.08 } else { 0.08 };
+    let mut vx = rng.gen_range(-0.25_f32..=0.25_f32);
+    let mut vy = rng.gen_range(-0.12_f32..=0.12_f32);
+    if vx.abs() < 0.03 {
+        vx = if vx.is_sign_negative() { -0.04 } else { 0.04 };
     }
-    if vy.abs() < 0.02 {
-        vy = if vy.is_sign_negative() { -0.03 } else { 0.03 };
+    if vy.abs() < 0.012 {
+        vy = if vy.is_sign_negative() { -0.015 } else { 0.015 };
     }
 
     state.fishes.push(FishInstance {

src/widgets/asciiquarium.rs

@@ -319,6 +319,7 @@ fn ensure_environment_initialized(state: &mut AquariumState) {
 /// Update the aquarium by one tick with simple wall-bounce physics and environment.
 pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
     let (aw, ah) = (state.size.0 as f32, state.size.1 as f32);
+    let dt: f32 = 0.033;
 
     // Ensure environment exists.
     ensure_environment_initialized(state);
@@ -332,7 +333,7 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
         state.env.ships.push(Ship {
             x: -(sw as f32),
             y: 0,
-            vx: 1.0,
+            vx: 6.0,
         });
     }
     if state.env.sharks.is_empty() {
@@ -343,7 +344,7 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
         state.env.sharks.push(Shark {
             x: -40.0,
             y,
-            vx: 1.2,
+            vx: 8.0,
         });
     }
     if state.env.whales.is_empty() {
@@ -352,12 +353,12 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
         state.env.whales.push(Whale {
             x: state.size.0 as f32 + 10.0,
             y,
-            vx: -0.6,
+            vx: -4.0,
         });
     }
     for fish in &mut state.fishes {
-        fish.position.0 += fish.velocity.0;
-        fish.position.1 += fish.velocity.1;
+        fish.position.0 += fish.velocity.0 * dt;
+        fish.position.1 += fish.velocity.1 * dt;
 
         let (fw, fh) = assets
             .get(fish.fish_art_index)
@@ -398,16 +399,16 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
             };
             state.bubbles.push(Bubble {
                 position: (bx, mid_y),
-                velocity: (0.0, -0.3),
+                velocity: (0.0, -3.0),
             });
         }
     }
 
     // Update bubbles (rise) and cull above waterline (y < 0).
     let mut kept = Vec::with_capacity(state.bubbles.len());
     for mut b in state.bubbles.drain(..) {
-        b.position.0 += b.velocity.0;
-        b.position.1 += b.velocity.1;
+        b.position.0 += b.velocity.0 * dt;
+        b.position.1 += b.velocity.1 * dt;
         if b.position.1 >= 0.0 {
             kept.push(b);
         }
@@ -416,7 +417,7 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
 
     // Move ships.
     for ship in &mut state.env.ships {
-        ship.x += ship.vx;
+        ship.x += ship.vx * dt;
         let (sw, _) = if ship.vx >= 0.0 {
             measure_block(SHIP_R)
         } else {
@@ -431,7 +432,7 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
 
     // Move sharks.
     for shark in &mut state.env.sharks {
-        shark.x += shark.vx;
+        shark.x += shark.vx * dt;
         let (sw, _) = if shark.vx >= 0.0 {
             measure_block(SHARK_R)
         } else {
@@ -448,7 +449,7 @@ pub fn update_aquarium(state: &mut AquariumState, assets: &[FishArt]) {
 
     // Move whales.
     for whale in &mut state.env.whales {
-        whale.x += whale.vx;
+        whale.x += whale.vx * dt;
         let (ww, _) = if whale.vx >= 0.0 {
             measure_block(WHALE_R)
         } else {