From 167e31655b63aa4d4548532cf0410cea9fd145ca Mon Sep 17 00:00:00 2001
From: Kai Stevenson <kai@kaistevenson.com>
Date: Sun, 9 Aug 2026 16:30:29 -0700
Subject: drawing

---
 src/sim/board.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 src/sim/board.rs

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

diff --git a/src/sim/board.rs b/src/sim/board.rs
new file mode 100644
index 0000000..4cc5756
--- /dev/null
+++ b/src/sim/board.rs
@@ -0,0 +1,72 @@
+use crate::config::{PIXEL_BUFFER_HEIGHT, PIXEL_BUFFER_WIDTH};
+
+type MaterialId = u16;
+
+#[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 {
+        Cell {
+            material: 0,
+            velocity_x: 0,
+            velocity_y: 0,
+            flags: 0,
+        }
+    }
+}
+
+pub struct Board {
+    pub size_x: u32,
+    pub size_y: u32,
+    pub cells: Vec<Cell>,
+}
+
+impl Board {
+    pub fn index_to_position(&self, idx: usize) -> (i32, i32) {
+        let y = idx / self.size_x as usize;
+        let x = idx % self.size_x as usize;
+        let board_x = x as i32 - self.size_x as i32 / 2;
+        let board_y = y as i32 - self.size_x as i32 / 2;
+        return (board_x, board_y);
+    }
+    pub fn set_cell_at_position(&mut self, x: i32, y: i32, c: Cell) {
+        // TODO: option?
+        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 position_to_index(&self, x: i32, y: i32) -> Option<usize> {
+        let board_x = x + self.size_x as i32 / 2;
+        let board_y = y + self.size_y as i32 / 2;
+
+        let on_board = board_x >= 0
+            && board_x < self.size_x as i32
+            && board_y >= 0
+            && board_y < self.size_y as i32;
+
+        if !on_board {
+            return None;
+        }
+
+        return Some((board_y * self.size_x as i32 + board_x) as usize);
+    }
+    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];
+
+        Board {
+            size_x,
+            size_y,
+            cells,
+        }
+    }
+}
-- 
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