Apparently the bounce is still broken. It always was.

src/direction.rs

@@ -1,10 +1,10 @@
 #[derive(Clone, Debug)]
-pub struct Direction {
+pub struct Coord {
     pub x: isize,
     pub y: isize
 }
 
-impl Direction {
+impl Coord {
     pub fn new(x: isize, y: isize) -> Self {
         Self { x, y }
     }

src/npc.rs

@@ -1,4 +1,27 @@
-use crate::{cell::{Cell, CellVariance}, direction::Direction, stage::{self, Stage}, HEIGHT, WIDTH};
+use std::cell;
+
+use crate::{
+    cell::{Cell, CellVariance},
+    direction::Coord,
+    stage::{self, Stage},
+    HEIGHT, WIDTH,
+};
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum Direction {
+    TOP,    /* 💪 */
+    BOTTOM, /* 👉👈🥺 */
+    LEFT,
+    RIGHT,
+}
+
+#[derive(Clone, Debug)]
+pub struct Neighbour {
+    pub cell: Cell,
+    pub direction: Direction,
+    pub pos_x: usize,
+    pub pos_y: usize,
+}
 
 #[derive(Clone, Debug)]
 pub struct NPC {
@@ -6,40 +29,24 @@ pub struct NPC {
     pub obstructed_from: Vec<CellVariance>,
     pub pos_x: usize,
     pub pos_y: usize,
-    pub direction: Direction,
+    pub direction: Coord,
 }
 
 impl NPC {
-    pub fn new(
-        pos_x: usize,
-        pos_y: usize,
-        direction: Direction,
-        walk_on: CellVariance,
-        obstructed_from: Vec<CellVariance>,
-    ) -> Self {
-        Self {
-            walk_on,
-            obstructed_from,
-            pos_x,
-            pos_y,
-            direction,
-        }
-    }
-
-    pub fn new_day(pos_x: usize, pos_y: usize, direction: Direction) -> Self {
+    pub fn new_day(pos_x: usize, pos_y: usize, direction: Coord) -> Self {
         Self {
             walk_on: CellVariance::DAY,
-            obstructed_from: vec![CellVariance::NIGHT],
+            obstructed_from: vec![CellVariance::NIGHT, CellVariance::VOID],
             pos_x,
             pos_y,
             direction,
         }
     }
 
-    pub fn new_night(pos_x: usize, pos_y: usize, direction: Direction) -> Self {
+    pub fn new_night(pos_x: usize, pos_y: usize, direction: Coord) -> Self {
         Self {
             walk_on: CellVariance::NIGHT,
-            obstructed_from: vec![CellVariance::DAY],
+            obstructed_from: vec![CellVariance::DAY, CellVariance::VOID],
             pos_x,
             pos_y,
             direction,
@@ -51,41 +58,130 @@ impl NPC {
         Cell::new(self.obstructed_from[0])
     }
 
-    pub fn process_bounce(&mut self, mut stage: &Stage) {
-        println!("Calc bounce for {:?}", self);
-        let obstacle = self.next_position();
-        
+    pub fn process_bounce(&mut self, map: &Vec<Cell>) -> Option<Neighbour> {
         // Get the current and next positions
-        let (curr_x, curr_y) = (self.pos_x, self.pos_y);
-        let (next_x, next_y) = obstacle;
+        
         let mut next_direction = self.direction.clone();
+        
+        // If we are here, we know that we hit something.
+        match self.check_neighborhood(map) {
+            None => {
+                self.move_next();
+                return None;
+            }
+            Some(neighbour) => {
+                if neighbour.direction == Direction::LEFT || neighbour.direction == Direction::RIGHT
+                {
+                    next_direction.x *= -1;
+                } else {
+                    next_direction.y *= -1;
+                }
 
-        // Hit top from below || Hit bottom from above
-        let hit_head = next_y > curr_y || curr_y > next_y;
+                // Return the new bounce direction
+                self.direction = next_direction;
 
-        // Hit right from left || Hit left from right
-        let hit_side = next_x > curr_x || curr_x > next_x;
+                self.move_next();
 
-        if hit_head {
-            next_direction.y *= -1;
+                // Don't tell update function that we hit a void block, to avoid overriding it.
+                // We changed direction anyway.
+                if neighbour.cell.variance != CellVariance::VOID {
+                    return Some(neighbour);
+                }
+
+                None
+            }
         }
-
-        // Hit right from left || Hit left from right
-        if hit_side {
-            next_direction.x *= -1;
-        }
-
-        // Return the new bounce direction
-        self.direction = next_direction;
-
-        let _ = self.pos_x.checked_add_signed(self.direction.x);
-        let _ = self.pos_y.checked_add_signed(self.direction.y);
     }
 
-    pub fn next_position(&self) -> (usize, usize) {
+    fn check_neighborhood(&self, map: &Vec<Cell>) -> Option<Neighbour> {
+        if self.pos_y == 0 && self.direction.y == -1 {
+            return Some(Neighbour {
+                cell: map[0],
+                direction: Direction::TOP,
+                pos_x: 0,
+                pos_y: 0,
+            });
+        }
+
+        if self.pos_x == 0 && self.direction.x == -1 {
+            return Some(Neighbour {
+                cell: map[0],
+                direction: Direction::LEFT,
+                pos_x: 0,
+                pos_y: 0,
+            });
+        }
+
+        let left = (self.pos_x.checked_sub(1).unwrap_or(0), self.pos_y);
+        let right = (self.pos_x.checked_add(1).unwrap_or(0), self.pos_y);
+        let top = (self.pos_x, self.pos_y.checked_sub(1).unwrap_or(0));
+        let bottom = (self.pos_x, (self.pos_y.checked_add(1).unwrap_or(0)));
+
+        let cell_left = map.get(left.0 + left.1 * WIDTH).unwrap_or(&Cell {
+            variance: CellVariance::VOID,
+        });
+        let cell_right = map.get(right.0 + right.1 * WIDTH).unwrap_or(&Cell {
+            variance: CellVariance::VOID,
+        });
+        let cell_top = map.get(top.0 + top.1 * WIDTH).unwrap_or(&Cell {
+            variance: CellVariance::VOID,
+        });
+        let cell_bottom = map.get(bottom.0 + bottom.1 * WIDTH).unwrap_or(&Cell {
+            variance: CellVariance::VOID,
+        });
+
+        if self.obstructed_from.contains(&cell_left.variance) {
+            return Some(Neighbour {
+                cell: cell_left.clone(),
+                direction: Direction::LEFT,
+                pos_x: left.0,
+                pos_y: left.1,
+            });
+        }
+        if self.obstructed_from.contains(&cell_right.variance) {
+            return Some(Neighbour {
+                cell: cell_right.clone(),
+                direction: Direction::RIGHT,
+                pos_x: right.0,
+                pos_y: right.1,
+            });
+        }
+        if self.obstructed_from.contains(&cell_top.variance) {
+            return Some(Neighbour {
+                cell: cell_top.clone(),
+                direction: Direction::TOP,
+                pos_x: top.0,
+                pos_y: top.1,
+            });
+        }
+        if self.obstructed_from.contains(&cell_bottom.variance) {
+            return Some(Neighbour {
+                cell: cell_bottom.clone(),
+                direction: Direction::BOTTOM,
+                pos_x: bottom.0,
+                pos_y: bottom.1,
+            });
+        }
+
+        return None;
+    }
+
+    pub fn move_next(&mut self) {
+        let mov_x = self.pos_x.checked_add_signed(self.direction.x);
+        let mov_y = self.pos_y.checked_add_signed(self.direction.y);
+
+        if mov_x.is_none() || mov_y.is_none() {
+            println!("Illegal move prevented");
+        } else {
+            self.pos_x = mov_x.unwrap();
+            self.pos_y = mov_y.unwrap();
+        }
+    }
+
+    pub fn next_position(&self) -> (Option<usize>, Option<usize>) {
         (
-            (self.pos_x as isize + self.direction.x).clamp(0, WIDTH.try_into().unwrap()) as usize,
-            (self.pos_y as isize + self.direction.y).clamp(0, HEIGHT.try_into().unwrap()) as usize
+            (self.pos_x.checked_add_signed(self.direction.x)),
+            (self.pos_y.checked_add_signed(self.direction.y)),
         )
     }
 }

src/stage.rs

@@ -10,7 +10,7 @@ use randomize::PCG32;
 
 use crate::cell::Cell;
 use crate::cell::CellVariance;
-use crate::direction::Direction;
+use crate::direction::Coord;
 use crate::npc::NPC;
 
 #[derive(Debug, Clone)]
@@ -116,10 +116,10 @@ impl Stage {
         let npc: NPC;
         match cell.variance {
             CellVariance::DAY => {
-                npc = NPC::new_day(pos_x, pos_y, Direction::new(-1, -1));
+                npc = NPC::new_day(pos_x, pos_y, Coord::new(-1, -1));
             }
             CellVariance::NIGHT => {
-                npc = NPC::new_night(pos_x, pos_y, Direction::new(-1, -1));
+                npc = NPC::new_night(pos_x, pos_y, Coord::new(-1, -1));
             }
             CellVariance::VOID => {
                 // Ignore this stupid request.
@@ -173,8 +173,13 @@ impl Stage {
     pub fn update(&mut self) {
         // Process bounce logic
         for npc in self.npcs.iter_mut() {
-            let me = &self;
-            npc.process_bounce(self);
+            match npc.process_bounce(&self.cells_dup) {
+                Some(n) => {
+                    let c = self.cells[n.pos_x + n.pos_y * self.width];
+                    self.cells[n.pos_x + n.pos_y * self.width] = c.invert();
+                },
+                None => {}
+            }
         }
 
         // Write current background