From 5d299af0e592c76c62c6347152eae2257a95c71f Mon Sep 17 00:00:00 2001
From: Micha White <botahamec@outlook.com>
Date: Sat, 1 Oct 2022 17:52:50 -0400
Subject: Quick and dirty texture atlases

---
 src/lib.rs      |  2 ++
 src/renderer.rs |  2 ++
 src/texture.rs  | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 src/texture.rs

(limited to 'src')

diff --git a/src/lib.rs b/src/lib.rs
index bacb53d..1453ef0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,6 @@
 #![feature(let_else)]
 #![feature(nonzero_min_max)]
+#![feature(type_alias_impl_trait)]
 #![warn(clippy::pedantic)]
 #![warn(clippy::nursery)]
 #![allow(clippy::module_name_repetitions)]
@@ -8,6 +9,7 @@ pub mod camera;
 pub mod config;
 pub mod instance;
 pub mod renderer;
+mod texture;
 mod vertex;
 
 pub(crate) use camera::Camera;
diff --git a/src/renderer.rs b/src/renderer.rs
index 55333f4..d45233b 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -35,11 +35,13 @@ pub enum NewRendererError {
 	#[error(transparent)]
 	NoGpu(#[from] NoGpuError),
 	#[error(transparent)]
+	// TODO better error
 	WindowInitError(#[from] OsError),
 }
 
 #[derive(Debug)]
 pub struct Renderer {
+	// TODO move some of this data elsewhere
 	surface: wgpu::Surface,
 	surface_config: wgpu::SurfaceConfiguration,
 	supported_present_modes: Box<[wgpu::PresentMode]>,
diff --git a/src/texture.rs b/src/texture.rs
new file mode 100644
index 0000000..aa6f871
--- /dev/null
+++ b/src/texture.rs
@@ -0,0 +1,89 @@
+use std::error::Error;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use image::error::DecodingError;
+use image::{DynamicImage, ImageError};
+use texture_packer::{
+	exporter::{ExportResult, ImageExporter},
+	MultiTexturePacker, TexturePackerConfig,
+};
+use thiserror::Error;
+
+static NEXT_TEXTURE_ID: AtomicUsize = AtomicUsize::new(0);
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+struct TextureId(usize);
+
+impl TextureId {
+	pub fn new() -> Self {
+		Self(NEXT_TEXTURE_ID.fetch_add(1, Ordering::Relaxed))
+	}
+}
+
+type PackError = impl std::fmt::Debug;
+
+#[derive(Error, Debug)]
+pub enum TextureError {
+	#[error("{:?}", .0)]
+	TextureTooLarge(PackError), // use an error with a source
+	#[error("{}", .0)]
+	BadImage(#[source] DecodingError), // TODO don't export this
+	#[error("Unexpected Error (this is a bug in alligator_render): {}", .0)]
+	Unexpected(#[source] Box<dyn Error>),
+}
+
+impl From<ImageError> for TextureError {
+	fn from(ie: ImageError) -> Self {
+		match ie {
+			ImageError::Decoding(de) => Self::BadImage(de),
+			_ => Self::Unexpected(Box::new(ie)),
+		}
+	}
+}
+
+struct TextureAtlases<'a> {
+	packer: MultiTexturePacker<'a, image::RgbaImage, TextureId>,
+}
+
+impl<'a> Default for TextureAtlases<'a> {
+	fn default() -> Self {
+		Self {
+			packer: MultiTexturePacker::new_skyline(TexturePackerConfig::default()),
+		}
+	}
+}
+
+impl<'a> TextureAtlases<'a> {
+	/// Creates a new texture atlas, with the given size
+	// TODO why is this u32?
+	pub fn new(width: u32, height: u32) -> Self {
+		Self {
+			packer: MultiTexturePacker::new_skyline(TexturePackerConfig {
+				max_width: width,
+				max_height: height,
+				..Default::default()
+			}),
+		}
+	}
+
+	// TODO specify format
+	// TODO support RGBA16
+	pub fn load_from_memory(&mut self, buf: &[u8]) -> Result<TextureId, TextureError> {
+		let img = image::load_from_memory(buf)?.into_rgba8();
+		let id = TextureId::new();
+		self.packer
+			.pack_own(id, img)
+			.map_err(TextureError::TextureTooLarge)?;
+
+		Ok(id)
+	}
+
+	pub(crate) fn atlases(&self) -> ExportResult<Box<[DynamicImage]>> {
+		self.packer
+			.get_pages()
+			.iter()
+			.map(ImageExporter::export)
+			.collect::<ExportResult<Vec<DynamicImage>>>()
+			.map(Vec::into_boxed_slice)
+	}
+}
-- 
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