From 6f67586b8fc6efdb86d0c9a9744c546da97c4dab Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Tue, 11 Aug 2026 00:46:56 -0700
Subject: physics for sand and water

---
 src/sim/board.rs | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

(limited to 'src/sim/board.rs')

diff --git a/src/sim/board.rs b/src/sim/board.rs
index 4cc5756..7af19be 100644
--- a/src/sim/board.rs
+++ b/src/sim/board.rs
@@ -1,24 +1,24 @@
-use crate::config::{PIXEL_BUFFER_HEIGHT, PIXEL_BUFFER_WIDTH};
-
-type MaterialId = u16;
+use crate::{
+    config::{PIXEL_BUFFER_HEIGHT, PIXEL_BUFFER_WIDTH},
+    sim::materials::MaterialId,
+};
 
 #[derive(Clone, Copy)]
 pub struct Cell {
     pub material: MaterialId,
-    pub velocity_x: i8,
-    pub velocity_y: i8,
     pub flags: u8,
 }
 
 impl Cell {
-    fn empty() -> Cell {
+    pub fn void() -> Cell {
         Cell {
-            material: 0,
-            velocity_x: 0,
-            velocity_y: 0,
+            material: MaterialId::Void,
             flags: 0,
         }
     }
+    pub fn from_material(material: MaterialId) -> Cell {
+        Cell { material, flags: 0 }
+    }
 }
 
 pub struct Board {
@@ -40,8 +40,8 @@ impl Board {
         let idx = self.position_to_index(x, y).unwrap();
         self.cells[idx] = c;
     }
-    pub fn cell_at_position(&self, x: i32, y: i32) -> Option<&Cell> {
-        Some(&self.cells[self.position_to_index(x, y)?])
+    pub fn cell_at_position(&self, x: i32, y: i32) -> Option<Cell> {
+        Some(self.cells[self.position_to_index(x, y)?])
     }
     pub fn position_to_index(&self, x: i32, y: i32) -> Option<usize> {
         let board_x = x + self.size_x as i32 / 2;
@@ -61,7 +61,7 @@ impl Board {
     pub fn empty() -> Board {
         let size_x = PIXEL_BUFFER_WIDTH * 2;
         let size_y = PIXEL_BUFFER_HEIGHT * 2;
-        let cells: Vec<Cell> = vec![Cell::empty(); (size_x * size_y) as usize];
+        let cells: Vec<Cell> = vec![Cell::void(); (size_x * size_y) as usize];
 
         Board {
             size_x,
-- 
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