3 files changed, 26 insertions, 36 deletions

diff --git a/src/sim/materials/mod.rs b/src/sim/materials/mod.rs
index 410236d..86ae7d5 100644
--- a/src/sim/materials/mod.rs
+++ b/src/sim/materials/mod.rs
@@ -14,7 +14,7 @@ pub enum MaterialId {
 
 pub struct MaterialDef {
     pub name: &'static str,
-    pub color: [u8; 4],
+    pub color: (u8, u8, u8, u8),
     pub density: u8,
     pub sim_update: Option<fn(ctx: &mut UpdateCtx) -> ()>,
 }
@@ -22,25 +22,25 @@ pub struct MaterialDef {
 static MATERIALS: [MaterialDef; 4] = [
     MaterialDef {
         name: "Void",
-        color: [0x00, 0x00, 0x00, 0xFF],
+        color: (0x00, 0x00, 0x00, 0xFF),
         density: 0,
         sim_update: None,
     },
     MaterialDef {
         name: "Sand",
-        color: [0xDE, 0xCB, 0x85, 0xFF],
+        color: (0xDE, 0xCB, 0x85, 0xFF),
         density: 50,
         sim_update: Some(sand::sim_update),
     },
     MaterialDef {
         name: "Wood",
-        color: [0x85, 0x56, 0x1D, 0xFF],
+        color: (0x85, 0x56, 0x1D, 0xFF),
         density: 50,
         sim_update: None,
     },
     MaterialDef {
         name: "Water",
-        color: [0x38, 0xA9, 0xFF, 0xFF],
+        color: (0x38, 0xA9, 0xFF, 0xFF),
         density: 40,
         sim_update: Some(water::sim_update),
     },
diff --git a/src/sim/materials/sand.rs b/src/sim/materials/sand.rs
index 6a780f3..ac8889f 100644
--- a/src/sim/materials/sand.rs
+++ b/src/sim/materials/sand.rs
@@ -3,8 +3,8 @@ use crate::sim::sim::UpdateCtx;
 #[inline]
 pub fn sim_update(ctx: &mut UpdateCtx) {
     ctx.candidates_swap(&[
-        (ctx.self_x, ctx.self_y + 1),
-        (ctx.self_x - 1 + 2 * ctx.seqno_parity as i32, ctx.self_y + 1),
-        (ctx.self_x + 1 - 2 * ctx.seqno_parity as i32, ctx.self_y + 1),
+        (0, 1),
+        (-1 + 2 * ctx.seqno_parity as i32, 1),
+        (1 - 2 * ctx.seqno_parity as i32, 1),
     ]);
 }
diff --git a/src/sim/materials/water.rs b/src/sim/materials/water.rs
index d875aee..65782dd 100644
--- a/src/sim/materials/water.rs
+++ b/src/sim/materials/water.rs
@@ -4,21 +4,21 @@ use crate::sim::sim::UpdateCtx;
 pub fn sim_update(ctx: &mut UpdateCtx) {
     // if the water can fall, do so
     if ctx.candidates_swap(&[
-        (ctx.self_x, ctx.self_y + 1),
-        (ctx.self_x - 1 + 2 * ctx.seqno_parity as i32, ctx.self_y + 1),
-        (ctx.self_x + 1 - 2 * ctx.seqno_parity as i32, ctx.self_y + 1),
+        (0, 1),
+        (-1 + 2 * ctx.seqno_parity as i32, 1),
+        (1 - 2 * ctx.seqno_parity as i32, 1),
     ]) {
         return;
     }
 
     // if the water can't fall, check if we can move left or right
     // these are inverted on parity so that we don't preference a direction
-    let left_target = ctx.board.cell_at_position(ctx.self_x - 1, ctx.self_y);
-    let can_move_left = left_target
-        .is_some_and(|c| c.material.def().density < ctx.self_cell.material.def().density);
-    let right_target = ctx.board.cell_at_position(ctx.self_x + 1, ctx.self_y);
-    let can_move_right = right_target
-        .is_some_and(|c| c.material.def().density < ctx.self_cell.material.def().density);
+    let left_target = ctx.get_cell(-1, 0);
+    let can_move_left =
+        left_target.is_some_and(|c| c.material.def().density < ctx.material.density);
+    let right_target = ctx.get_cell(1, 0);
+    let can_move_right =
+        right_target.is_some_and(|c| c.material.def().density < ctx.material.density);
 
     // we can't move down or to other side, so we're stuck
     if !can_move_left && !can_move_right {
@@ -40,39 +40,29 @@ pub fn sim_update(ctx: &mut UpdateCtx) {
         }
 
         let offset = side * (1 + i / 2);
-        let hole_target = ctx
-            .board
-            .cell_at_position(ctx.self_x + offset, ctx.self_y + 1);
+        let hole_target = ctx.get_cell(offset, 1);
         if let Some(target) = hole_target
-            && target.material.def().density < ctx.self_cell.material.def().density
+            && target.material.def().density < ctx.material.density
         {
             // we identified a hole and we know that the space on this side is open
             // move toward the hole
-            let move_target = if side == 1 { right_target } else { left_target }.clone();
             // new_target.flags = new_target.flags ^ 0b1;
-            // safe to unwrap
-            ctx.board
-                .set_cell_at_position(ctx.self_x, ctx.self_y, move_target.unwrap());
-            ctx.board
-                .set_cell_at_position(ctx.self_x + side, ctx.self_y, ctx.self_cell);
+            ctx.candidates_swap(&[(side, 0)]);
             return;
         }
     }
 
     // we didn't find a hole, so just move "randomly" on the same surface
     // TODO when to settle?
-    let (target, target_x) = if !can_move_left {
-        (right_target, 1)
+    let target_x = if !can_move_left {
+        1
     } else if !can_move_right {
-        (left_target, -1)
+        -1
     } else if ctx.seqno_parity % 2 == 1 {
-        (right_target, 1)
+        1
     } else {
-        (left_target, -1)
+        -1
     };
 
-    ctx.board
-        .set_cell_at_position(ctx.self_x, ctx.self_y, target.unwrap());
-    ctx.board
-        .set_cell_at_position(ctx.self_x + target_x, ctx.self_y, ctx.self_cell);
+    ctx.candidates_swap(&[(target_x, 0)]);
 }