add HDR image loader

Using the `image` crate, HDR images can be loaded into RGBA-f32 textures.

CREDITS.md

@@ -15,3 +15,4 @@
 ## Assets
 
 * Generic RPG Pack (CC0 license) by [Bakudas](https://twitter.com/bakudas) and [Gabe Fern](https://twitter.com/_Gabrielfer)
+* Environment maps (`.hdr` files) from [HDRIHaven](https://hdrihaven.com) (CC0 license)

crates/bevy_render/Cargo.toml

@@ -22,6 +22,7 @@ spirv-reflect = "0.2.3"
 glsl-to-spirv = { git = "https://github.com/cart/glsl-to-spirv" }
 # TODO: move this to its own crate
 png = "0.16.0"
+image = "0.23"
 
 # misc
 log = { version = "0.4", features = ["release_max_level_info"] }

crates/bevy_render/src/lib.rs

@@ -38,7 +38,7 @@ use render_graph::{
 };
 use renderer::{AssetRenderResourceBindings, RenderResourceBindings};
 use std::ops::Range;
-use texture::{PngTextureLoader, TextureResourceSystemState};
+use texture::{HdrTextureLoader, PngTextureLoader, TextureResourceSystemState};
 
 pub mod stage {
     /// Stage where render resources are set up
@@ -75,6 +75,7 @@ impl AppPlugin for RenderPlugin {
             .add_asset::<Texture>()
             .add_asset::<Shader>()
             .add_asset::<PipelineDescriptor>()
+            .add_asset_loader::<Texture, HdrTextureLoader>()
             .add_asset_loader::<Texture, PngTextureLoader>()
             .register_component::<Camera>()
             .register_component::<Draw>()

crates/bevy_render/src/texture/hdr_texture_loader.rs

@@ -0,0 +1,43 @@
+use super::{Texture, TextureFormat};
+use anyhow::Result;
+use bevy_asset::AssetLoader;
+use bevy_math::Vec2;
+use std::path::Path;
+
+#[derive(Clone, Default)]
+pub struct HdrTextureLoader;
+
+impl AssetLoader<Texture> for HdrTextureLoader {
+    fn from_bytes(&self, _asset_path: &Path, bytes: Vec<u8>) -> Result<Texture> {
+        let format = TextureFormat::Rgba32Float;
+        debug_assert_eq!(
+            format.pixel_size(),
+            4 * 4 * 1,
+            "Format should have 32bit x 4 size"
+        );
+
+        let decoder = image::hdr::HdrDecoder::new(bytes.as_slice())?;
+        let info = decoder.metadata();
+        let rgb_data = decoder.read_image_hdr()?;
+        let mut rgba_data = Vec::with_capacity(rgb_data.len() * format.pixel_size());
+
+        for rgb in rgb_data {
+            let alpha = 1.0f32;
+
+            rgba_data.extend_from_slice(&rgb.0[0].to_ne_bytes());
+            rgba_data.extend_from_slice(&rgb.0[1].to_ne_bytes());
+            rgba_data.extend_from_slice(&rgb.0[2].to_ne_bytes());
+            rgba_data.extend_from_slice(&alpha.to_ne_bytes());
+        }
+
+        Ok(Texture::new(
+            Vec2::new(info.width as f32, info.height as f32),
+            rgba_data,
+            format,
+        ))
+    }
+    fn extensions(&self) -> &[&str] {
+        static EXTENSIONS: &[&str] = &["hdr"];
+        EXTENSIONS
+    }
+}

crates/bevy_render/src/texture/mod.rs

@@ -1,9 +1,11 @@
+mod hdr_texture_loader;
 mod png_texture_loader;
 mod sampler_descriptor;
 mod texture;
 mod texture_descriptor;
 mod texture_dimension;
 
+pub use hdr_texture_loader::*;
 pub use png_texture_loader::*;
 pub use sampler_descriptor::*;
 pub use texture::*;

crates/bevy_render/src/texture/texture.rs

@@ -67,7 +67,8 @@ impl Texture {
         self.size = size;
         let width = size.x() as usize;
         let height = size.y() as usize;
-        self.data.resize(width * height * self.format.pixel_size(), 0);
+        self.data
+            .resize(width * height * self.format.pixel_size(), 0);
     }
 
     pub fn texture_resource_system(