Added hidden texture support in packer

crates/packer/src/atlasset.rs

@@ -4,6 +4,7 @@ use image::{imageops, GenericImageView, ImageBuffer, Rgba, RgbaImage};
 use std::{
 	fs::File,
 	io::{Read, Write},
+	num::NonZeroU32,
 	path::{Path, PathBuf},
 };
 
@@ -205,19 +206,19 @@ impl AtlasSet {
 			)
 		})?;
 
-		self.index
+		self.index.push(
-			.path_map
+			p,
-			.insert(p.to_path_buf(), self.index.index.len() as u32);
+			SpriteAtlasImage {
-
-		self.index.index.push(SpriteAtlasImage {
 				true_size: image_dim,
-			idx: self.index.index.len() as u32,
+				// Add one to account for hidden texture
+				idx: NonZeroU32::new(self.index.len() as u32 + 1).unwrap(),
 				atlas: atlas_idx as u32,
 				x: (x + self.image_margin) as f32 / self.texture_width as f32,
 				y: (y + self.image_margin) as f32 / self.texture_height as f32,
 				w: image_dim.0 as f32 / self.texture_width as f32,
 				h: image_dim.1 as f32 / self.texture_height as f32,
-		});
+			},
+		);
 
 		return Ok(atlas_idx);
 	}

crates/packer/src/lib.rs

@@ -2,7 +2,11 @@
 
 //! This crate creates texture atlases from an asset tree.
 
-use std::{collections::HashMap, path::PathBuf};
+use std::{
+	collections::HashMap,
+	num::NonZeroU32,
+	path::{Path, PathBuf},
+};
 
 use serde::{Deserialize, Serialize};
 
@@ -13,8 +17,9 @@ pub struct SpriteAtlasImage {
 	/// This is an index in SpriteAtlas.atlas_list
 	pub atlas: u32,
 
-	/// A globally unique, consecutively numbered index for this sprite
+	/// A globally unique, consecutively numbered index for this sprite.
-	pub idx: u32,
+	/// This is nonzero because index zero is reserved for the "hidden" texture.
+	pub idx: NonZeroU32,
 
 	/// The size of this image, in pixels
 	pub true_size: (u32, u32),
@@ -41,10 +46,10 @@ pub struct SpriteAtlasImage {
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct SpriteAtlas {
 	/// The images in this atlas
-	pub index: Vec<SpriteAtlasImage>,
+	pub(crate) index: Vec<SpriteAtlasImage>,
 
 	/// Map paths to image indices
-	pub path_map: HashMap<PathBuf, u32>,
+	path_map: HashMap<PathBuf, NonZeroU32>,
 
 	/// The file names of the atlas textures we've generated
 	pub atlas_list: Vec<String>,
@@ -59,4 +64,30 @@ impl SpriteAtlas {
 			atlas_list: Vec::new(),
 		}
 	}
+
+	/// Get a SpriteAtlasImage by index
+	pub fn get_by_idx(&self, idx: NonZeroU32) -> &SpriteAtlasImage {
+		&self.index[idx.get() as usize - 1]
+	}
+
+	/// Get an image index from its path
+	/// returns None if this path isn't in this index
+	pub fn get_idx_by_path(&self, path: &Path) -> Option<NonZeroU32> {
+		self.path_map.get(path).map(|x| *x)
+	}
+
+	/// Get the number of images in this atlas
+	pub fn len(&self) -> u32 {
+		self.index.len() as u32
+	}
+
+	/// Add an image with the given path to this index
+	pub fn push(&mut self, p: &Path, i: SpriteAtlasImage) {
+		self.path_map.insert(
+			p.to_path_buf(),
+			NonZeroU32::new(self.index.len() as u32 + 1).unwrap(),
+		);
+
+		self.index.push(i);
+	}
 }