feat: add aspect ratio demo bin

src/bin/aspect_demo.rs

@@ -0,0 +1,130 @@
+use std::time::{Duration, Instant};
+
+use sdl2::event::Event;
+use sdl2::keyboard::Keycode;
+use sdl2::pixels::Color;
+use sdl2::rect::Rect;
+
+// A self-contained SDL2 demo showing how to keep a consistent aspect ratio
+// with letterboxing/pillarboxing in a resizable window.
+//
+// This uses SDL2's logical size feature, which automatically sets a viewport
+// to preserve the target aspect ratio and adds black bars as needed.
+// We also clear the full window to black and then clear the logical viewport
+// to a content color, so bars remain visibly black.
+
+const LOGICAL_WIDTH: u32 = 320; // target content width
+const LOGICAL_HEIGHT: u32 = 180; // target content height (16:9)
+
+fn main() -> Result<(), String> {
+    // Initialize SDL2
+    let sdl = sdl2::init()?;
+    let video = sdl.video()?;
+
+    // Create a resizable window
+    let window = video
+        .window("SDL2 Aspect Ratio Demo", 960, 540)
+        .resizable()
+        .position_centered()
+        .build()
+        .map_err(|e| e.to_string())?;
+
+    let mut canvas = window.into_canvas().build().map_err(|e| e.to_string())?;
+
+    // Set the desired logical (virtual) resolution. SDL will letterbox/pillarbox
+    // as needed to preserve this aspect ratio when the window is resized.
+    canvas
+        .set_logical_size(LOGICAL_WIDTH, LOGICAL_HEIGHT)
+        .map_err(|e| e.to_string())?;
+    // Optional: uncomment to enforce integer scaling only (more retro look)
+    // canvas.set_integer_scale(true)?;
+
+    let mut events = sdl.event_pump()?;
+
+    let mut running = true;
+    let start = Instant::now();
+    let mut last_log = Instant::now();
+
+    while running {
+        for event in events.poll_iter() {
+            match event {
+                Event::Quit { .. }
+                | Event::KeyDown {
+                    keycode: Some(Keycode::Escape),
+                    ..
+                } => {
+                    running = false;
+                }
+                Event::Window { win_event, .. } => {
+                    // Periodically log window size and the computed viewport
+                    // to demonstrate how letterboxing/pillarboxing behaves.
+                    use sdl2::event::WindowEvent;
+                    match win_event {
+                        WindowEvent::Resized(_, _)
+                        | WindowEvent::SizeChanged(_, _)
+                        | WindowEvent::Maximized
+                        | WindowEvent::Restored => {
+                            if last_log.elapsed() > Duration::from_millis(250) {
+                                let out_size = canvas.output_size()?;
+                                let viewport = canvas.viewport();
+                                println!(
+                                    "window={}x{}, viewport x={}, y={}, w={}, h={}",
+                                    out_size.0,
+                                    out_size.1,
+                                    viewport.x(),
+                                    viewport.y(),
+                                    viewport.width(),
+                                    viewport.height()
+                                );
+                                last_log = Instant::now();
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        // 1) Clear the entire window to black (no viewport) so the bars are black
+        canvas.set_viewport(None);
+        canvas.set_draw_color(Color::RGB(0, 0, 0));
+        canvas.clear();
+
+        // 2) Re-apply logical size so SDL sets a viewport that preserves aspect
+        //    ratio. Clearing now only affects the letterboxed content area.
+        canvas
+            .set_logical_size(LOGICAL_WIDTH, LOGICAL_HEIGHT)
+            .map_err(|e| e.to_string())?;
+
+        // Fill the content area with a background color to differentiate from bars
+        canvas.set_draw_color(Color::RGB(30, 30, 40));
+        canvas.clear();
+
+        // Draw a simple grid to visualize scaling clearly
+        canvas.set_draw_color(Color::RGB(60, 60, 90));
+        let step = 20i32;
+        for x in (0..=LOGICAL_WIDTH as i32).step_by(step as usize) {
+            let _ = canvas.draw_line(sdl2::rect::Point::new(x, 0), sdl2::rect::Point::new(x, LOGICAL_HEIGHT as i32));
+        }
+        for y in (0..=LOGICAL_HEIGHT as i32).step_by(step as usize) {
+            let _ = canvas.draw_line(sdl2::rect::Point::new(0, y), sdl2::rect::Point::new(LOGICAL_WIDTH as i32, y));
+        }
+
+        // Draw a border around the logical content area
+        canvas.set_draw_color(Color::RGB(200, 200, 220));
+        let border = Rect::new(0, 0, LOGICAL_WIDTH, LOGICAL_HEIGHT);
+        canvas.draw_rect(border)?;
+
+        // Draw a moving box to demonstrate dynamic content staying within aspect
+        let elapsed_ms = start.elapsed().as_millis() as i32;
+        let t = (elapsed_ms / 8) % LOGICAL_WIDTH as i32;
+        let box_rect = Rect::new(t - 10, (LOGICAL_HEIGHT as i32 / 2) - 10, 20, 20);
+        canvas.set_draw_color(Color::RGB(255, 140, 0));
+        canvas.fill_rect(box_rect).ok();
+
+        canvas.present();
+    }
+
+    Ok(())
+}

src/systems/input.rs

@@ -15,6 +15,12 @@ use crate::{
     map::direction::Direction,
 };
 
+// Touch input constants
+const TOUCH_DIRECTION_THRESHOLD: f32 = 10.0;
+const TOUCH_EASING_DISTANCE_THRESHOLD: f32 = 1.0;
+const MAX_TOUCH_MOVEMENT_SPEED: f32 = 100.0;
+const TOUCH_EASING_FACTOR: f32 = 1.5;
+
 #[derive(Resource, Default, Debug, Copy, Clone)]
 pub enum CursorPosition {
     #[default]
@@ -47,35 +53,6 @@ impl TouchData {
             current_direction: None,
         }
     }
-
-    pub fn update_position(&mut self, new_pos: Vec2) -> Option<Direction> {
-        self.current_pos = new_pos;
-        let delta = new_pos - self.start_pos;
-
-        // Minimum threshold for direction detection (in pixels)
-        const THRESHOLD: f32 = 20.0;
-
-        if delta.length() < THRESHOLD {
-            self.current_direction = None;
-            return None;
-        }
-
-        // Determine primary direction based on larger component
-        let direction = if delta.x.abs() > delta.y.abs() {
-            if delta.x > 0.0 {
-                Direction::Right
-            } else {
-                Direction::Left
-            }
-        } else if delta.y > 0.0 {
-            Direction::Down
-        } else {
-            Direction::Up
-        };
-
-        self.current_direction = Some(direction);
-        Some(direction)
-    }
 }
 
 #[derive(Resource, Debug, Clone)]
@@ -178,6 +155,55 @@ pub fn process_simple_key_events(bindings: &mut Bindings, frame_events: &[Simple
     emitted_events
 }
 
+/// Calculates the primary direction from a 2D vector delta
+fn calculate_direction_from_delta(delta: Vec2) -> Direction {
+    if delta.x.abs() > delta.y.abs() {
+        if delta.x > 0.0 {
+            Direction::Right
+        } else {
+            Direction::Left
+        }
+    } else if delta.y > 0.0 {
+        Direction::Down
+    } else {
+        Direction::Up
+    }
+}
+
+/// Updates the touch reference position with easing
+///
+/// This slowly moves the start_pos towards the current_pos, with the speed
+/// decreasing as the distance gets smaller. The maximum movement speed is capped.
+/// Returns the delta vector and its length for reuse by the caller.
+fn update_touch_reference_position(touch_data: &mut TouchData, delta_time: f32) -> (Vec2, f32) {
+    // Calculate the vector from start to current position
+    let delta = touch_data.current_pos - touch_data.start_pos;
+    let distance = delta.length();
+
+    // If there's no significant distance, nothing to do
+    if distance < TOUCH_EASING_DISTANCE_THRESHOLD {
+        return (delta, distance);
+    }
+
+    // Calculate speed based on distance (slower as it gets closer)
+    // The easing function creates a curve where movement slows down as it approaches the target
+    let speed = (distance / TOUCH_EASING_FACTOR).min(MAX_TOUCH_MOVEMENT_SPEED);
+
+    // Calculate movement distance for this frame
+    let movement_amount = speed * delta_time;
+
+    // If the movement would overshoot, just set to target
+    if movement_amount >= distance {
+        touch_data.start_pos = touch_data.current_pos;
+    } else {
+        // Use direct vector scaling instead of normalization
+        let scale_factor = movement_amount / distance;
+        touch_data.start_pos += delta * scale_factor;
+    }
+
+    (delta, distance)
+}
+
 pub fn input_system(
     delta_time: Res<DeltaTime>,
     mut bindings: ResMut<Bindings>,
@@ -216,9 +242,7 @@ pub fn input_system(
 
                 // Handle mouse motion as touch motion for desktop testing
                 if let Some(ref mut touch_data) = touch_state.active_touch {
-                    if let Some(direction) = touch_data.update_position(Vec2::new(x as f32, y as f32)) {
+                    touch_data.current_pos = Vec2::new(x as f32, y as f32);
-                        writer.write(GameEvent::Command(GameCommand::MovePlayer(direction)));
-                    }
                 }
             }
             // Handle mouse events as touch for desktop testing
@@ -242,9 +266,7 @@ pub fn input_system(
                     if touch_data.finger_id == finger_id {
                         let screen_x = x * crate::constants::CANVAS_SIZE.x as f32;
                         let screen_y = y * crate::constants::CANVAS_SIZE.y as f32;
-                        if let Some(direction) = touch_data.update_position(Vec2::new(screen_x, screen_y)) {
+                        touch_data.current_pos = Vec2::new(screen_x, screen_y);
-                            writer.write(GameEvent::Command(GameCommand::MovePlayer(direction)));
-                        }
                     }
                 }
             }
@@ -283,6 +305,25 @@ pub fn input_system(
         writer.write(event);
     }
 
+    // Update touch reference position with easing
+    if let Some(ref mut touch_data) = touch_state.active_touch {
+        // Apply easing to the reference position and get the delta for direction calculation
+        let (delta, distance) = update_touch_reference_position(touch_data, delta_time.0);
+
+        // Check for direction based on updated reference position
+        if distance >= TOUCH_DIRECTION_THRESHOLD {
+            let direction = calculate_direction_from_delta(delta);
+
+            // Only send command if direction has changed
+            if touch_data.current_direction != Some(direction) {
+                touch_data.current_direction = Some(direction);
+                writer.write(GameEvent::Command(GameCommand::MovePlayer(direction)));
+            }
+        } else if touch_data.current_direction.is_some() {
+            touch_data.current_direction = None;
+        }
+    }
+
     if let (false, CursorPosition::Some { remaining_time, .. }) = (cursor_seen, &mut *cursor) {
         *remaining_time -= delta_time.0;
         if *remaining_time <= 0.0 {