1 files changed, 250 insertions, 0 deletions
diff --git a/render/src/texture.rs b/render/src/texture.rs
new file mode 100644
index 0000000..76e77a8
--- /dev/null
+++ b/render/src/texture.rs
@@ -0,0 +1,250 @@
+use std::error::Error;
+use std::num::NonZeroU32;
+use std::sync::Arc;
+
+use alligator_resources::texture::{LoadError, Rgba16Texture, TextureId, TextureManager};
+use image::{EncodableLayout, GenericImage, RgbaImage};
+use texture_packer::TexturePacker;
+use texture_packer::{
+	exporter::{ExportResult, ImageExporter},
+	TexturePackerConfig,
+};
+use thiserror::Error;
+
+/// The texture did not fit in the texture atlas
+#[derive(Debug, Error)]
+#[error("{:?}", .0)]
+pub struct PackError(PackErrorInternal);
+
+// TODO this can be removed when a new texture packer is made
+type PackErrorInternal = impl std::fmt::Debug;
+
+#[derive(Error, Debug)]
+pub enum TextureError {
+	#[error("{:?}", .0)]
+	TextureTooLarge(#[from] PackError),
+	#[error("{}", .0)]
+	BadImage(#[from] LoadError),
+	#[error("Unexpected Error (this is a bug in alligator_render): {}", .0)]
+	Unexpected(#[source] Box<dyn Error>),
+}
+
+/// Simpler constructor for a wgpu extent3d
+const fn extent_3d(width: u32, height: u32) -> wgpu::Extent3d {
+	wgpu::Extent3d {
+		width,
+		height,
+		depth_or_array_layers: 1,
+	}
+}
+
+/// A texture atlas, usable by the renderer
+// TODO make this Debug
+// TODO make these resizable
+pub struct TextureAtlas {
+	textures: Arc<TextureManager>,
+	packer: TexturePacker<'static, Rgba16Texture, TextureId>,
+	diffuse_texture: wgpu::Texture,
+	diffuse_bind_group: wgpu::BindGroup,
+	image: RgbaImage,
+	width: u32,
+	height: u32,
+	changed: bool,
+}
+
+macro_rules! texture_info {
+	($name: ident, $prop: ident, $divisor: ident) => {
+		pub fn $name(&mut self, id: TextureId) -> Result<f32, TextureError> {
+			let frame = match self.texture_frame(id) {
+				Some(frame) => frame,
+				None => {
+					self.load_texture(id)?;
+					self.texture_frame(id).unwrap()
+				}
+			};
+			let property = frame.frame.$prop;
+			let value = property as f32 / self.$divisor as f32;
+			Ok(value)
+		}
+	};
+}
+
+impl TextureAtlas {
+	/// Creates a new texture atlas, with the given size
+	// TODO why is this u32?
+	// TODO this is still too large
+	pub fn new(
+		device: &wgpu::Device,
+		textures: Arc<TextureManager>,
+		width: u32,
+		height: u32,
+	) -> (Self, wgpu::BindGroupLayout) {
+		let atlas_size = extent_3d(width, height);
+		let diffuse_texture = device.create_texture(&wgpu::TextureDescriptor {
+			label: Some("Diffuse Texture"),
+			size: atlas_size,
+			mip_level_count: 1,
+			sample_count: 1,
+			dimension: wgpu::TextureDimension::D2,
+			format: wgpu::TextureFormat::Rgba8Unorm,
+			usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_DST,
+			view_formats: &[wgpu::TextureFormat::Rgba8UnormSrgb],
+		});
+
+		// TODO I don't think this refreshes anything
+		let diffuse_texture_view =
+			diffuse_texture.create_view(&wgpu::TextureViewDescriptor::default());
+
+		let diffuse_sampler = device.create_sampler(&wgpu::SamplerDescriptor::default());
+
+		let texture_bind_group_layout =
+			device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+				label: Some("Texture Bind Group Layout"),
+				entries: &[
+					wgpu::BindGroupLayoutEntry {
+						binding: 0,
+						visibility: wgpu::ShaderStages::FRAGMENT,
+						ty: wgpu::BindingType::Texture {
+							sample_type: wgpu::TextureSampleType::Float { filterable: true },
+							view_dimension: wgpu::TextureViewDimension::D2,
+							multisampled: false,
+						},
+						count: None,
+					},
+					wgpu::BindGroupLayoutEntry {
+						binding: 1,
+						visibility: wgpu::ShaderStages::FRAGMENT,
+						ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+						count: None,
+					},
+				],
+			});
+
+		let diffuse_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+			label: Some("Diffuse Bind Group"),
+			layout: &texture_bind_group_layout,
+			entries: &[
+				wgpu::BindGroupEntry {
+					binding: 0,
+					resource: wgpu::BindingResource::TextureView(&diffuse_texture_view),
+				},
+				wgpu::BindGroupEntry {
+					binding: 1,
+					resource: wgpu::BindingResource::Sampler(&diffuse_sampler),
+				},
+			],
+		});
+
+		(
+			Self {
+				textures,
+				packer: TexturePacker::new_skyline(TexturePackerConfig {
+					max_width: width,
+					max_height: height,
+					allow_rotation: false,
+					trim: false,
+					texture_padding: 0,
+					..Default::default()
+				}),
+				diffuse_texture,
+				diffuse_bind_group,
+				width,
+				height,
+				image: RgbaImage::from_raw(
+					width,
+					height,
+					vec![0; 4 * width as usize * height as usize],
+				)
+				.unwrap(),
+				changed: true,
+			},
+			texture_bind_group_layout,
+		)
+	}
+
+	/// get the bind group for the texture
+	pub(crate) const fn bind_group(&self) -> &wgpu::BindGroup {
+		&self.diffuse_bind_group
+	}
+
+	/// Load a new subtexture from memory
+	pub fn load_texture(&mut self, id: TextureId) -> Result<TextureId, TextureError> {
+		self.changed = true;
+		let img = self.textures.load_texture(id)?;
+		self.packer.pack_own(id, img).map_err(PackError)?;
+		Ok(id)
+	}
+
+	/// Get the frame for s particular subtexture
+	fn texture_frame(&self, id: TextureId) -> Option<&texture_packer::Frame<TextureId>> {
+		self.packer.get_frame(&id)
+	}
+
+	texture_info!(texture_width, w, width);
+	texture_info!(texture_height, h, height);
+	texture_info!(texture_x, x, width);
+	texture_info!(texture_y, y, height);
+
+	/// Fill the cached image
+	fn fill_image(&mut self) -> ExportResult<()> {
+		let atlas = {
+			profiling::scope!("export atlas");
+			ImageExporter::export(&self.packer)?
+		};
+		profiling::scope!("copy image");
+		self.image
+			.copy_from(&atlas, 0, 0)
+			.expect("image cache is too small");
+		Ok(())
+	}
+
+	/// Clear the texture atlas, and give it a new size
+	pub fn clear(&mut self, width: u32, height: u32) {
+		self.changed = true;
+		self.width = width;
+		self.height = height;
+		self.packer = TexturePacker::new_skyline(TexturePackerConfig {
+			max_width: self.width,
+			max_height: self.height,
+			..Default::default()
+		});
+	}
+
+	/// Fill the GPU texture atlas
+	#[profiling::function]
+	pub(crate) fn fill_textures(&mut self, queue: &wgpu::Queue) {
+		// saves time if nothing changed since the last time we did this
+		// FIXME This doesn't do much good once we get procedurally generated animation
+		//       We'll have to create our own texture packer, with mutable subtextures,
+		//       and more efficient algorithms. This'll also make frame times more consistent
+		if !self.changed {
+			return;
+		}
+
+		let atlas_size = extent_3d(self.width, self.height);
+
+		// put the packed texture into the base image
+		if let Err(e) = self.fill_image() {
+			log::error!("{}", e);
+		}
+
+		// copy that to the gpu
+		queue.write_texture(
+			wgpu::ImageCopyTexture {
+				texture: &self.diffuse_texture,
+				mip_level: 0,
+				origin: wgpu::Origin3d::ZERO,
+				aspect: wgpu::TextureAspect::All,
+			},
+			self.image.as_bytes(),
+			wgpu::ImageDataLayout {
+				offset: 0,
+				bytes_per_row: NonZeroU32::new(atlas_size.width * 4),
+				rows_per_image: NonZeroU32::new(atlas_size.height),
+			},
+			atlas_size,
+		);
+
+		self.changed = false;
+	}
+}