the line shrinks after me

also 1d or 2d graphs are possible

src/main.rs

@@ -5,6 +5,7 @@ use macroquad::prelude::*;
 
 const DOT_RADIUS: f32 = 1.0;
 
+#[derive(Clone,Copy)]
 struct Dot {
     x: f32,
     y: f32,
@@ -48,46 +49,119 @@ impl DebugWindow {
 }
 
 
+enum Axis {
+    One,
+    Two
+}
+
+struct Tail {
+    points: [Dot; 500],
+    head: usize,
+    axis: Axis,
+    x_offset: f32,
+    y_offset: f32,
+    px_per_s: f32,
+}
+impl Tail {
+    fn new(axis: Axis) -> Self {
+        
+        let (x_offset, y_offset) = match axis {
+            Axis::One => (0., screen_height() /2.),
+            Axis::Two => (screen_width() /2., screen_height() /2.),
+        };
+        
+        Self {
+            // start all the dots off screen
+            points: [Dot::new(-1.,-1.); 500],
+            head: 0,
+            axis,
+            x_offset,
+            y_offset,
+            px_per_s: 500.,
+        }
+    }
+    fn place_next(&mut self, delta_time: f32, x_displace: f32, y_displace: f32) {
+        match self.axis {
+            Axis::One => {
+                // x will scroll while y gets displaced
+                if self.x_offset >= screen_width() {
+                    self.x_offset = 0.;
+                } else {
+                    self.x_offset = self.x_offset + (delta_time * self.px_per_s)
+                }
+                self.push(Dot::new(self.x_offset, self.y_offset+y_displace));
+            },
+            Axis::Two => {
+                // both x and y will get displaced
+                self.push(Dot::new(self.x_offset+x_displace,self.y_offset+y_displace))
+            },
+        }     
+    } 
+    fn push(&mut self, dot: Dot) {
+        if self.head >= self.points.len() -1 {
+            self.head = 0
+        } else {
+            self.head += 1
+        }
+
+        self.points[self.head] = dot;
+    }
+    fn draw(&self) {
+        // TODO fadding alpha?
+        self.points.iter().for_each(|d| d.draw());
+    }
+    fn dots(&self) -> usize {
+        self.points.len()
+    }
+}
+
 #[macroquad::main("Graph")]
 async fn main() {
     // Dot params 
-    let y_offset = screen_height() / 2.0;
-    let mut x_offset = screen_width();
-    let mut trail: Vec<Dot> = Vec::new();
+    let mut y_displacement = 0.;
+    let mut x_displacement = 0.;
+    let mut tail = Tail::new(Axis::Two);
 
     // Selection box
     let mut inital_x_pos = 0.;
     let mut inital_y_pos = 0.;
     
     // Tooling
-    let mut show_debug = false;
-    let mut px_per_s: f32 = 100.;
-
+    let mut show_debug = true;
+    let mut px_per_s: f32 = 1000.;
 
     let stdin = stdin();
     let handle= stdin.lock();
+
     loop {
         clear_background(BLACK);
 
-        // handle.
         let delta_time = get_frame_time();
 
-        if x_offset >= screen_width() {
-            // wrap once you've hit the end of the line
-            x_offset = 0.;
-            trail.clear();
-        } else {
-            x_offset = x_offset + (delta_time * px_per_s);
+        tail.place_next(delta_time, x_displacement, y_displacement);
+        tail.draw();
+
+        if is_key_down(KeyCode::S) {
+            if y_displacement < screen_height()/2. {
+                y_displacement += 10.;
             }
-
-        let x  = 0.+x_offset;
-        let y  = 0.+y_offset;
-
-        let dot = Dot::new(x,y);
-        trail.push(dot);
-        trail.iter().for_each(|d| d.draw());
-
-        if is_key_pressed(KeyCode::D) {
+        }
+        if is_key_down(KeyCode::W) {
+            if y_displacement > -(screen_height()/2.) {
+                y_displacement -= 10.;
+            }
+        }
+        if is_key_down(KeyCode::D) {
+            if x_displacement < screen_width()/2. {
+                x_displacement += 10.;
+            }
+        }
+        if is_key_down(KeyCode::A) {
+            if x_displacement > -(screen_width()/2.) {
+                x_displacement -= 10.;
+            }
+        }
+        if is_key_pressed(KeyCode::F3) {
             show_debug = !show_debug;
         }
         if is_key_pressed(KeyCode::Up) {
@@ -112,9 +186,9 @@ async fn main() {
         if show_debug {
             let mut debug = DebugWindow::new();
             debug.add_line(format!("FPS {}, Latency {:.2}ms", get_fps(), delta_time * 1000.0));
-            debug.add_line(format!("px/s {}", px_per_s));
-            debug.add_line(format!("Dots {}", trail.len()));
+            debug.add_line(format!("Dots {}", tail.dots()));
             debug.add_line(format!("Cursor Pos {:?}", mouse_position()));
+            debug.add_line(format!("px/s {}", px_per_s));
             debug.draw();
         }