v0.7: A* pathfinding, mouse control, step-up, jump limits

- A* pathfinding for actor (find_path in actors.rs)
- Right-click sets target (actor_goto), finds ground below air clicks
- Actor follows path with horizontal velocity + jumping
- Step-up: actor climbs 1-4px small edges/obstacles
- Jump height limited to 40px in pathfinding (avoids unreachable targets)
- Powder displacement when walking through sand/dirt
- Actor collision: solids block, powders pass-through
- Fallback: direct movement if no path found

engine/src/actors.rs

@@ -1,4 +1,6 @@
 use crate::grid::Grid;
+use std::cmp::Ordering;
+use std::collections::BinaryHeap;
 
 pub struct Actor {
     pub x: f32,
@@ -8,15 +10,54 @@ pub struct Actor {
     pub vx: f32,
     pub vy: f32,
     pub color: [u8; 3],
+    path: Vec<(i32, i32)>,
+    path_index: usize,
+    speed: f32,
 }
 
 impl Actor {
     pub fn new(x: f32, y: f32, w: u32, h: u32, color: [u8; 3]) -> Self {
-        Self { x, y, w, h, vx: 0.0, vy: 0.0, color }
+        Self { x, y, w, h, vx: 0.0, vy: 0.0, color, path: Vec::new(), path_index: 0, speed: 120.0 }
+    }
+
+    pub fn goto(&mut self, grid: &Grid, target_x: f32, target_y: f32) {
+        let sx = self.x.round() as i32;
+        let sy = (self.y + self.h as f32 / 2.0).round() as i32;
+        let tx = target_x.round() as i32;
+        let ty = target_y.round() as i32;
+        self.path = find_path(grid, self.w, self.h, sx, sy, tx, ty);
+        if self.path.is_empty() {
+            self.path = vec![(tx, ty)];
+        }
+        self.path_index = 0;
     }
 
     pub fn update(&mut self, grid: &Grid, dt: f32) {
         const GRAVITY: f32 = 500.0;
+
+        if !self.path.is_empty() && self.path_index < self.path.len() {
+            let (wx, wy) = self.path[self.path_index];
+            let cx = self.x + self.w as f32 / 2.0;
+            let cy = self.y + self.h as f32 / 2.0;
+            let dx = wx as f32 - cx;
+            let dy = wy as f32 - cy;
+            let dist = (dx * dx + dy * dy).sqrt();
+
+            if dist < 3.0 {
+                self.path_index += 1;
+                if self.path_index >= self.path.len() {
+                    self.vx = 0.0;
+                    self.path.clear();
+                }
+            } else {
+                let spd = self.speed.min(dist * 10.0);
+                self.vx = dx / dist * spd;
+                if dy < -10.0 && self.vy == 0.0 {
+                    self.vy = -280.0;
+                }
+            }
+        }
+
         self.vy += GRAVITY * dt;
         self.vy = self.vy.clamp(-600.0, 600.0);
 
@@ -24,7 +65,23 @@ impl Actor {
         let new_y = (self.y + self.vy * dt).clamp(0.0, grid.height as f32 - self.h as f32);
 
         if self.vx != 0.0 && self.collides_at(grid, new_x, self.y) {
+            let mut stepped = false;
+            for step in 1u32..=4 {
+                let try_y = self.y - step as f32;
+                if try_y >= 0.0 && !self.collides_at(grid, new_x, try_y) {
+                    self.x = new_x;
+                    self.y = try_y;
+                    self.vy = 0.0;
+                    stepped = true;
+                    break;
+                }
+            }
+            if stepped {
+                return;
+            }
+            if !stepped {
                 self.vx = 0.0;
+            }
         } else {
             self.x = new_x;
         }
@@ -94,10 +151,111 @@ impl Actor {
                             placed = true;
                             break;
                         }
-    }
                     }
                     if placed { break; }
                 }
             }
         }
     }
+}
+
+#[derive(Clone, Eq, PartialEq)]
+struct Node {
+    x: i32,
+    y: i32,
+    g: i32,
+    f: i32,
+}
+
+impl Ord for Node {
+    fn cmp(&self, other: &Self) -> Ordering {
+        other.f.cmp(&self.f)
+    }
+}
+
+impl PartialOrd for Node {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+fn walkable(grid: &Grid, aw: u32, ah: u32, x: i32, y: i32) -> bool {
+    for dy in 0i32..ah as i32 {
+        for dx in 0i32..aw as i32 {
+            let gx = x + dx;
+            let gy = y + dy;
+            if gx < 0 || gy < 0 || gx >= grid.width as i32 || gy >= grid.height as i32 {
+                return false;
+            }
+            let mat = grid.get(gx as u32, gy as u32);
+            let props = &crate::material::PROPS[mat as usize];
+            if props.is_solid && !props.is_powder {
+                return false;
+            }
+        }
+    }
+    true
+}
+
+fn find_path(grid: &Grid, aw: u32, ah: u32, sx: i32, sy: i32, tx: i32, ty: i32) -> Vec<(i32, i32)> {
+    if !walkable(grid, aw, ah, tx, ty) {
+        return Vec::new();
+    }
+
+    let w = grid.width as i32;
+    let h = grid.height as i32;
+    let mut open = BinaryHeap::new();
+    let mut g_scores = vec![i32::MAX; (w * h) as usize];
+    let mut came_from = vec![-1i32; (w * h) as usize];
+
+    let start_idx = (sy * w + sx) as usize;
+    g_scores[start_idx] = 0;
+    let h_start = (tx - sx).abs() + (ty - sy).abs();
+    open.push(Node { x: sx, y: sy, g: 0, f: h_start });
+
+    let dirs = [(0, -1), (1, 0), (0, 1), (-1, 0), (-1, -1), (1, -1), (1, 1), (-1, 1)];
+
+    while let Some(current) = open.pop() {
+        if current.x == tx && current.y == ty {
+            let mut path = Vec::new();
+            let mut cx = tx;
+            let mut cy = ty;
+            path.push((cx, cy));
+            let mut idx = (cy * w + cx) as usize;
+            while came_from[idx] != -1 {
+                let prev = came_from[idx];
+                cx = prev % w;
+                cy = prev / w;
+                path.push((cx, cy));
+                idx = (cy * w + cx) as usize;
+            }
+            path.reverse();
+            if path.len() > 1 {
+                path.remove(0);
+            }
+            return path;
+        }
+
+        for &(dx, dy) in &dirs {
+            let nx = current.x + dx;
+            let ny = current.y + dy;
+            if nx < 0 || ny < 0 || nx >= w || ny >= h { continue; }
+            if !walkable(grid, aw, ah, nx, ny) { continue; }
+
+            if ny < current.y && (current.y - ny) > 40 { continue; }
+
+            let cost = if dx != 0 && dy != 0 { 14 } else { 10 };
+            let tentative_g = current.g + cost;
+            let nidx = (ny * w + nx) as usize;
+
+            if tentative_g < g_scores[nidx] {
+                g_scores[nidx] = tentative_g;
+                came_from[nidx] = (current.y * w + current.x) as i32;
+                let h = (tx - nx).abs() + (ty - ny).abs();
+                open.push(Node { x: nx, y: ny, g: tentative_g, f: tentative_g + h });
+            }
+        }
+    }
+
+    Vec::new()
+}

engine/src/lib.rs

@@ -163,7 +163,7 @@ pub fn move_actor(dx: f32, dy: f32) {
         if let Some(ref mut a) = e.actor {
             a.vx = dx * 150.0;
             if dy < 0.0 && a.vy == 0.0 {
-                a.vy = -400.0;
+                a.vy = -280.0;
             }
         }
     });
@@ -179,3 +179,25 @@ pub fn update_actor(dt: f32) {
         }
     });
 }
+
+#[wasm_bindgen]
+pub fn actor_goto(x: f32, y: f32) {
+    with_engine(|e| {
+        if let Some(ref mut a) = e.actor {
+            let ground_y = find_ground(&e.grid, x as i32, y as i32);
+            a.goto(&e.grid, x, ground_y as f32);
+        }
+    });
+}
+
+fn find_ground(grid: &Grid, x: i32, mut y: i32) -> i32 {
+    while y < grid.height as i32 {
+        let mat = grid.get(x as u32, y as u32);
+        let props = &crate::material::PROPS[mat as usize];
+        if props.is_solid && !props.is_powder {
+            return y - 1;
+        }
+        y += 1;
+    }
+    y
+}

web/src/engine.ts

@@ -13,6 +13,7 @@ import __wbg_init, {
   actor_y,
   move_actor,
   update_actor,
+  actor_goto,
 } from "../pkg/atomic_engine.js";
 
 export const M = {
@@ -89,6 +90,7 @@ export interface Engine {
   actorY: () => number;
   moveActor: (dx: number, dy: number) => void;
   updateActor: (dt: number) => void;
+  actorGoto: (x: number, y: number) => void;
   memory: WebAssembly.Memory;
 }
 
@@ -111,5 +113,6 @@ export async function createEngine(gridWidth: number, gridHeight: number): Promi
     actorY: () => actor_y(),
     moveActor: (dx, dy) => move_actor(dx, dy),
     updateActor: (dt) => update_actor(dt),
+    actorGoto: (x, y) => actor_goto(x, y),
   };
 }

web/src/input.ts

@@ -3,6 +3,7 @@ export class Input {
   mouseX = 0;
   mouseY = 0;
   mouseDown = false;
+  mouseRight = false;
   wheel = 0;
 
   constructor() {
@@ -12,11 +13,19 @@ export class Input {
       this.mouseX = e.clientX;
       this.mouseY = e.clientY;
     });
-    window.addEventListener("mousedown", () => (this.mouseDown = true));
+    window.addEventListener("mousedown", (e) => {
+      if (e.button === 2) {
+        this.mouseRight = true;
+        e.preventDefault();
+      } else {
+        this.mouseDown = true;
+      }
+    });
     window.addEventListener("mouseup", () => (this.mouseDown = false));
     window.addEventListener("wheel", (e) => {
       this.wheel += e.deltaY > 0 ? -1 : 1;
     });
+    window.addEventListener("contextmenu", (e) => e.preventDefault());
   }
 
   isDown(key: string): boolean {

web/src/main.ts

@@ -210,6 +210,11 @@ async function main() {
       const g = screenToGrid(input.mouseX, input.mouseY);
       engine.fillCircle(g.x, g.y, 6, paintMat);
     }
+    if (input.mouseRight) {
+      const g = screenToGrid(input.mouseX, input.mouseY);
+      engine.actorGoto(g.x, g.y);
+      input.mouseRight = false;
+    }
 
     camera.update(dt);
     engine.updateRender(