From 9bad77e68aef86b3a89425368d006caa58eb47fd Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Tue, 14 Apr 2026 11:35:52 +0200
Subject: [PATCH] Warn if using a software rasterizer (#8101)

* Related to https://github.com/emilk/egui/issues/8093
---
 crates/egui-wgpu/src/lib.rs | 41 +++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/crates/egui-wgpu/src/lib.rs b/crates/egui-wgpu/src/lib.rs
index eb04173b5..64e35511d 100644
--- a/crates/egui-wgpu/src/lib.rs
+++ b/crates/egui-wgpu/src/lib.rs
@@ -138,29 +138,12 @@ async fn request_adapter(
             }
         })?;
 
-    if cfg!(target_arch = "wasm32") {
-        log::debug!(
-            "Picked wgpu adapter: {}",
-            adapter_info_summary(&adapter.get_info())
+    if 1 < available_adapters.len() {
+        log::info!(
+            "There are {} available wgpu adapters: {}",
+            available_adapters.len(),
+            describe_adapters(available_adapters)
         );
-    } else {
-        // native:
-        if available_adapters.len() == 1 {
-            log::debug!(
-                "Picked the only available wgpu adapter: {}",
-                adapter_info_summary(&adapter.get_info())
-            );
-        } else {
-            log::info!(
-                "There were {} available wgpu adapters: {}",
-                available_adapters.len(),
-                describe_adapters(available_adapters)
-            );
-            log::debug!(
-                "Picked wgpu adapter: {}",
-                adapter_info_summary(&adapter.get_info())
-            );
-        }
     }
 
     Ok(adapter)
@@ -236,6 +219,8 @@ impl RenderState {
             }) => (adapter, device, queue),
         };
 
+        log_adapter_info(&adapter.get_info());
+
         let surface_formats = {
             profiling::scope!("get_capabilities");
             compatible_surface.map_or_else(
@@ -406,6 +391,18 @@ pub fn depth_format_from_bits(depth_buffer: u8, stencil_buffer: u8) -> Option<wg
 
 // ---------------------------------------------------------------------------
 
+fn log_adapter_info(info: &wgpu::AdapterInfo) {
+    let summary = adapter_info_summary(info);
+
+    let is_test = cfg!(test); // Software rasterizers are expected (and preferred) during testing!
+
+    if info.device_type == wgpu::DeviceType::Cpu && !is_test {
+        log::warn!("Software rasterizer detected - loss of performance expected. {summary}");
+    } else {
+        log::debug!("wgpu adapter: {summary}");
+    }
+}
+
 /// A human-readable summary about an adapter
 pub fn adapter_info_summary(info: &wgpu::AdapterInfo) -> String {
     let wgpu::AdapterInfo {