refresh intro levels 2-4, making them more like a tutorial

levels/chapter_01.json

@@ -22,6 +22,14 @@
 			"id": "digits",
 			"name": "Digits",
 			"description": "place digits and use number keys to assign them values",
+			"init_board": {
+				"grid": "           \n\n\n       o\n     o\n   o\n       1\n   4 8 7\n\n   I I I\n\n\n\n",
+				"comments": [
+					{ "text": "Digit tiles are consumed by marbles that pass over them,\n adding their value to the end of the marble's number", "x": 8, "y": 5 },
+					{ "text": "Try selecting this 7 with the digit tool (#) in your toolbar\n then change it to a 6 using your keyboard number keys", "x": 8, "y": 7 },
+					{ "text": "You can also use the arrow keys to move the selection around,\n if you need to type more numbers", "x": 8, "y": 10 }
+				]
+			},
 			"stages": [{
 				"input": [],
 				"output": [4, 8, 16]
@@ -31,7 +39,14 @@
 			"id": "loop",
 			"name": "Loop",
 			"description": "repeated output",
-			"init_board": "\n   \n o\n\n\n\n ^ \n\n",
+			"init_board": {
+				"grid": "           \n\n\n   v\n   o\n\n   *B  I\n\n\n   ^\n\n\n\n",
+				"comments": [
+					{ "text": "Arrows change the direction of marbles that collide with them", "x": 4, "y": 3 },
+					{ "text": " v Buttons are activated by marbles, and can power other machines", "x": 3, "y": 5 },
+					{ "text": "^ Silos create new marbles when powered", "x": 4, "y": 7 }
+				]
+			},
 			"stages": [{
 				"input": [],
 				"output": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
@@ -41,6 +56,12 @@
 			"id": "copy_input",
 			"name": "Copy Cat",
 			"description": "read input and output the same thing",
+			"init_board": {
+			    "grid": "           \n\n\n   v\n   o\n\n   *I  I\n\n\n   ^\n\n\n\n",
+				"comments": [
+					{ "text": "^ When an input/output silo is powered, it creates a new marble,\n containing the next value from the level input as a number", "x": 4, "y": 7 }
+				]
+			},
 			"stages": [{
 				"input": "Hello, world!",
 				"output": "Hello, world!"

src/board.rs

@@ -39,7 +39,7 @@ impl From<CompatBoard> for Board {
 	fn from(value: CompatBoard) -> Self {
 		match value {
 			CompatBoard::V1(string) => Self {
-				grid: Grid::parse(&string),
+				grid: Grid::from_ascii(&string),
 				comments: Vec::new(),
 			},
 			CompatBoard::V2 { grid, comments } => Self { grid, comments },
@@ -79,6 +79,7 @@ impl Board {
 		for comment in &self.comments {
 			let x = comment.x * tile_size + offset.x as i32;
 			let y = comment.y * tile_size + offset.y as i32;
+			let y = y + (tile_size - font_size) / 2; // center vertically in the grid row
 			for (i, line) in comment.text.lines().enumerate() {
 				let y = y + line_space * i as i32;
 				d.draw_text(line, x, y, font_size, Color::ORANGE);
@@ -149,7 +150,7 @@ impl Board {
 
 	pub fn from_user_str(source: &str) -> Self {
 		serde_json::from_str(source).unwrap_or_else(|_| Self {
-			grid: Grid::parse(source),
+			grid: Grid::from_ascii(source),
 			comments: Vec::new(),
 		})
 	}

src/marble_engine/grid.rs

@@ -53,7 +53,7 @@ impl ResizeDeltas {
 }
 
 impl Grid {
-	pub fn parse(source: &str) -> Self {
+	pub fn from_ascii(source: &str) -> Self {
 		let mut rows = Vec::new();
 
 		let mut width = 0;
@@ -79,13 +79,18 @@ impl Grid {
 		}
 	}
 
-	pub fn to_str(&self) -> String {
+	pub fn to_ascii(&self) -> String {
 		let mut out = String::new();
 		for y in 0..self.height {
 			for x in 0..self.width {
 				let tile = self.get((x, y).into()).unwrap();
 				out.push(tile.to_char());
 			}
+			if y > 0 {
+				while out.as_bytes().last() == Some(&b' ') {
+					out.pop();
+				}
+			}
 			out.push('\n');
 		}
 		out
@@ -269,12 +274,12 @@ impl Grid {
 
 impl From<String> for Grid {
 	fn from(value: String) -> Self {
-		Self::parse(&value)
+		Self::from_ascii(&value)
 	}
 }
 
 impl From<Grid> for String {
 	fn from(val: Grid) -> String {
-		val.to_str()
+		val.to_ascii()
 	}
 }

tests/main.rs

@@ -3,7 +3,7 @@ use marble_machinations::marble_engine::{grid::Grid, Machine};
 #[test]
 fn creating_marbles_cause_indirect_claim() {
 	let mut eng = Machine::new_empty();
-	eng.set_grid(Grid::parse(
+	eng.set_grid(Grid::from_ascii(
 		"
   I
 o 2