init wgpu + doc + err robustes

lib/context.rs

@@ -0,0 +1,62 @@
+//! # Context Module
+//!
+//! Initializes the GPU, creates the surface, and holds the Device and Queue. It is static (created once at startup).
+
+use std::sync::Arc;
+use wgpu::{Adapter, Device, Instance, Queue, Surface};
+use winit::window::Window;
+
+use crate::error::WsgError;
+
+/// Represents the GPU context. Holds all WGPU objects needed for rendering.
+/// Created once at startup and shared across frames via Arc.
+pub struct Context {
+    /// The entry point to wgpu — manages connections with graphics drivers (Vulkan, Metal, DX12).
+    pub instance: Instance,
+    /// Rendering target surface linking wgpu to the window (winit).
+    pub surface: Surface<'static>,
+    /// Physical or software GPU adapter selected by the user.
+    pub adapter: Adapter,
+    /// The engine core — creates buffers, textures, pipelines.
+    pub device: Device,
+    /// Command submission queue — drawing commands are sent here for execution.
+    pub queue: Queue,
+}
+
+impl Context {
+    /// Initializes the WGPU context. Creates the surface from the window, requests a device from the adapter,
+    /// and stores all required objects (instance, surface, adapter, device, queue).
+    /// Called once at application startup. Returns an error if GPU initialization fails.
+    pub async fn new(window: Arc<Window>) -> Result<Self, WsgError> {
+        // WGPU instance
+        let instance = wgpu::Instance::default();
+
+        // Surface (bound to window lifecycle, so unsafe)
+        let surface = instance
+            .create_surface(window)
+            .map_err(|e| WsgError::SurfaceCreation(e))?;
+
+        // Request for adapter (GPU)
+        let adapter = instance
+            .request_adapter(&wgpu::RequestAdapterOptions {
+                compatible_surface: Some(&surface),
+                ..Default::default()
+            })
+            .await
+            .map_err(|_| WsgError::NoAdapter)?;
+
+        // Request for adapter device and queue
+        let (device, queue) = adapter
+            .request_device(&wgpu::DeviceDescriptor::default())
+            .await
+            .map_err(|_| WsgError::DeviceCreation)?;
+
+        Ok(Self {
+            instance,
+            surface,
+            adapter,
+            device,
+            queue,
+        })
+    }
+}