From 7e66aa502ea5f399139cd80044a410ca5eaa4ca7 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Thu, 18 Jan 2024 16:40:30 +0100
Subject: [PATCH] We cannot list available adapters on web

---
 crates/egui-wgpu/src/lib.rs               | 17 ++++++++++++++++-
 crates/egui_demo_app/src/backend_panel.rs |  1 +
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/crates/egui-wgpu/src/lib.rs b/crates/egui-wgpu/src/lib.rs
index 95b44bc01cf..8aafc06b0a0 100644
--- a/crates/egui-wgpu/src/lib.rs
+++ b/crates/egui-wgpu/src/lib.rs
@@ -57,6 +57,10 @@ pub struct RenderState {
     pub adapter: Arc<wgpu::Adapter>,
 
     /// All the available adapters.
+    ///
+    /// This is not availabler on web.
+    /// On web, we always select WebGPU is available, then fall back to WebGL if not.
+    #[cfg(not(target_arch = "wasm32"))]
     pub available_adapters: Arc<[wgpu::Adapter]>,
 
     /// Wgpu device used for rendering, created from the adapter.
@@ -86,7 +90,9 @@ impl RenderState {
     ) -> Result<Self, WgpuError> {
         crate::profile_scope!("RenderState::create"); // async yield give bad names using `profile_function`
 
-        let available_adapters: Vec<_> = instance.enumerate_adapters(wgpu::Backends::all());
+        // This is always an empty list on web.
+        #[cfg(not(target_arch = "wasm32"))]
+        let available_adapters = instance.enumerate_adapters(wgpu::Backends::all());
 
         let adapter = {
             crate::profile_scope!("request_adapter");
@@ -118,6 +124,13 @@ impl RenderState {
                 })?
         };
 
+        #[cfg(target_arch = "wasm32")]
+        log::debug!(
+            "Picked wgpu adapter: {}",
+            adapter_info_summary(&adapter.get_info())
+        );
+
+        #[cfg(not(target_arch = "wasm32"))]
         if available_adapters.len() == 1 {
             log::debug!(
                 "Picked the only available wgpu adapter: {}",
@@ -152,6 +165,7 @@ impl RenderState {
 
         Ok(Self {
             adapter: Arc::new(adapter),
+            #[cfg(not(target_arch = "wasm32"))]
             available_adapters: available_adapters.into(),
             device: Arc::new(device),
             queue: Arc::new(queue),
@@ -161,6 +175,7 @@ impl RenderState {
     }
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 fn describe_adapters(adapters: &[wgpu::Adapter]) -> String {
     if adapters.is_empty() {
         "(none)".to_owned()
diff --git a/crates/egui_demo_app/src/backend_panel.rs b/crates/egui_demo_app/src/backend_panel.rs
index e8aebe7287c..2e2f0f0a71c 100644
--- a/crates/egui_demo_app/src/backend_panel.rs
+++ b/crates/egui_demo_app/src/backend_panel.rs
@@ -266,6 +266,7 @@ fn integration_ui(ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
             wgpu_adapter_ui(ui, &render_state.adapter);
             ui.end_row();
 
+            #[cfg(not(target_arch = "wasm32"))]
             if 1 < render_state.available_adapters.len() {
                 ui.label("Others:");
                 ui.vertical(|ui| {