1 files changed, 58 insertions, 6 deletions

diff --git a/wgpu/src/settings.rs b/wgpu/src/settings.rs
index bc146c4c..dc06b82d 100644
--- a/wgpu/src/settings.rs
+++ b/wgpu/src/settings.rs
@@ -1,15 +1,18 @@
 //! Configure a renderer.
 pub use crate::Antialiasing;
 
-/// The settings of a [`Renderer`].
+/// The settings of a [`Backend`].
 ///
-/// [`Renderer`]: ../struct.Renderer.html
+/// [`Backend`]: crate::Backend
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Settings {
-    /// The output format of the [`Renderer`].
+    /// The present mode of the [`Backend`].
     ///
-    /// [`Renderer`]: ../struct.Renderer.html
-    pub format: wgpu::TextureFormat,
+    /// [`Backend`]: crate::Backend
+    pub present_mode: wgpu::PresentMode,
+
+    /// The internal graphics backend to use.
+    pub internal_backend: wgpu::BackendBit,
 
     /// The bytes of the font that will be used by default.
     ///
@@ -21,17 +24,66 @@ pub struct Settings {
     /// By default, it will be set to 20.
     pub default_text_size: u16,
 
+    /// If enabled, spread text workload in multiple threads when multiple cores
+    /// are available.
+    ///
+    /// By default, it is disabled.
+    pub text_multithreading: bool,
+
     /// The antialiasing strategy that will be used for triangle primitives.
+    ///
+    /// By default, it is `None`.
     pub antialiasing: Option<Antialiasing>,
 }
 
+impl Settings {
+    /// Creates new [`Settings`] using environment configuration.
+    ///
+    /// Specifically:
+    ///
+    /// - The `internal_backend` can be configured using the `WGPU_BACKEND`
+    /// environment variable. If the variable is not set, the primary backend
+    /// will be used. The following values are allowed:
+    ///     - `vulkan`
+    ///     - `metal`
+    ///     - `dx12`
+    ///     - `dx11`
+    ///     - `gl`
+    ///     - `webgpu`
+    ///     - `primary`
+    pub fn from_env() -> Self {
+        Settings {
+            internal_backend: backend_from_env()
+                .unwrap_or(wgpu::BackendBit::PRIMARY),
+            ..Self::default()
+        }
+    }
+}
+
 impl Default for Settings {
     fn default() -> Settings {
         Settings {
-            format: wgpu::TextureFormat::Bgra8UnormSrgb,
+            present_mode: wgpu::PresentMode::Mailbox,
+            internal_backend: wgpu::BackendBit::PRIMARY,
             default_font: None,
             default_text_size: 20,
+            text_multithreading: false,
             antialiasing: None,
         }
     }
 }
+
+fn backend_from_env() -> Option<wgpu::BackendBit> {
+    std::env::var("WGPU_BACKEND").ok().map(|backend| {
+        match backend.to_lowercase().as_str() {
+            "vulkan" => wgpu::BackendBit::VULKAN,
+            "metal" => wgpu::BackendBit::METAL,
+            "dx12" => wgpu::BackendBit::DX12,
+            "dx11" => wgpu::BackendBit::DX11,
+            "gl" => wgpu::BackendBit::GL,
+            "webgpu" => wgpu::BackendBit::BROWSER_WEBGPU,
+            "primary" => wgpu::BackendBit::PRIMARY,
+            other => panic!("Unknown backend: {}", other),
+        }
+    })
+}