From f76b3c4230e890e3cdeb01c26809cf4bde8d26f4 Mon Sep 17 00:00:00 2001
From: Wilhelm Vallrand <44950746+vallrand@users.noreply.github.com>
Date: Fri, 19 May 2023 23:11:41 +0300
Subject: [PATCH] Fix bloom wasm support (#8631)

# Objective

- Fixes #7352

## Solution

GLES doesn't support binding specific mip levels for sampling. Fallback
to using separate textures instead.
-
[wgpu-hal/src/gles/device.rs](https://github.com/gfx-rs/wgpu/blob/628a95cd1c27abce4d4ff2ffe4558cc4ef1e7fd3/wgpu-hal/src/gles/device.rs#L1038)

---

---------

Co-authored-by: Wilhelm Vallrand <>
---
 Cargo.toml                                 |  4 +--
 crates/bevy_core_pipeline/src/bloom/mod.rs | 42 +++++++++++++++++++---
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 0e1b5d9f33..7698dc2ec8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -274,7 +274,7 @@ path = "examples/2d/bloom_2d.rs"
 name = "2D Bloom"
 description = "Illustrates bloom post-processing in 2d"
 category = "2D Rendering"
-wasm = false
+wasm = true
 
 [[example]]
 name = "move_sprite"
@@ -535,7 +535,7 @@ path = "examples/3d/bloom_3d.rs"
 name = "3D Bloom"
 description = "Illustrates bloom configuration using HDR and emissive materials"
 category = "3D Rendering"
-wasm = false
+wasm = true
 
 [[example]]
 name = "load_gltf"
diff --git a/crates/bevy_core_pipeline/src/bloom/mod.rs b/crates/bevy_core_pipeline/src/bloom/mod.rs
index 7157bc449e..3c41ca716e 100644
--- a/crates/bevy_core_pipeline/src/bloom/mod.rs
+++ b/crates/bevy_core_pipeline/src/bloom/mod.rs
@@ -302,11 +302,16 @@ impl ViewNode for BloomNode {
 #[derive(Component)]
 struct BloomTexture {
     // First mip is half the screen resolution, successive mips are half the previous
+    #[cfg(any(not(feature = "webgl"), not(target_arch = "wasm32")))]
     texture: CachedTexture,
+    // WebGL does not support binding specific mip levels for sampling, fallback to separate textures instead
+    #[cfg(all(feature = "webgl", target_arch = "wasm32"))]
+    texture: Vec<CachedTexture>,
     mip_count: u32,
 }
 
 impl BloomTexture {
+    #[cfg(any(not(feature = "webgl"), not(target_arch = "wasm32")))]
     fn view(&self, base_mip_level: u32) -> TextureView {
         self.texture.texture.create_view(&TextureViewDescriptor {
             base_mip_level,
@@ -314,6 +319,16 @@ impl BloomTexture {
             ..Default::default()
         })
     }
+    #[cfg(all(feature = "webgl", target_arch = "wasm32"))]
+    fn view(&self, base_mip_level: u32) -> TextureView {
+        self.texture[base_mip_level as usize]
+            .texture
+            .create_view(&TextureViewDescriptor {
+                base_mip_level: 0,
+                mip_level_count: Some(1u32),
+                ..Default::default()
+            })
+    }
 }
 
 fn prepare_bloom_textures(
@@ -347,10 +362,29 @@ fn prepare_bloom_textures(
                 view_formats: &[],
             };
 
-            commands.entity(entity).insert(BloomTexture {
-                texture: texture_cache.get(&render_device, texture_descriptor),
-                mip_count,
-            });
+            #[cfg(any(not(feature = "webgl"), not(target_arch = "wasm32")))]
+            let texture = texture_cache.get(&render_device, texture_descriptor);
+            #[cfg(all(feature = "webgl", target_arch = "wasm32"))]
+            let texture: Vec<CachedTexture> = (0..mip_count)
+                .map(|mip| {
+                    texture_cache.get(
+                        &render_device,
+                        TextureDescriptor {
+                            size: Extent3d {
+                                width: (texture_descriptor.size.width >> mip).max(1),
+                                height: (texture_descriptor.size.height >> mip).max(1),
+                                depth_or_array_layers: 1,
+                            },
+                            mip_level_count: 1,
+                            ..texture_descriptor.clone()
+                        },
+                    )
+                })
+                .collect();
+
+            commands
+                .entity(entity)
+                .insert(BloomTexture { texture, mip_count });
         }
     }
 }