feat(editor): add ViewportTexture offscreen render target

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/voltex_editor/src/lib.rs

@@ -5,6 +5,7 @@ pub mod renderer;
 pub mod ui_context;
 pub mod widgets;
 pub mod dock;
+pub mod orbit_camera;
 
 pub use font::FontAtlas;
 pub use draw_list::{DrawVertex, DrawCommand, DrawList};
@@ -12,3 +13,7 @@ pub use layout::LayoutState;
 pub use renderer::UiRenderer;
 pub use ui_context::UiContext;
 pub use dock::{DockTree, DockNode, Axis, Rect, LeafLayout};
+pub use orbit_camera::OrbitCamera;
+
+pub mod viewport_texture;
+pub use viewport_texture::{ViewportTexture, VIEWPORT_COLOR_FORMAT, VIEWPORT_DEPTH_FORMAT};

crates/voltex_editor/src/viewport_texture.rs

@@ -0,0 +1,69 @@
+pub const VIEWPORT_COLOR_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;
+pub const VIEWPORT_DEPTH_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Depth32Float;
+
+pub struct ViewportTexture {
+    pub color_texture: wgpu::Texture,
+    pub color_view: wgpu::TextureView,
+    pub depth_texture: wgpu::Texture,
+    pub depth_view: wgpu::TextureView,
+    pub width: u32,
+    pub height: u32,
+}
+
+impl ViewportTexture {
+    pub fn new(device: &wgpu::Device, width: u32, height: u32) -> Self {
+        let w = width.max(1);
+        let h = height.max(1);
+
+        let color_texture = device.create_texture(&wgpu::TextureDescriptor {
+            label: Some("Viewport Color"),
+            size: wgpu::Extent3d {
+                width: w,
+                height: h,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: VIEWPORT_COLOR_FORMAT,
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
+            view_formats: &[],
+        });
+        let color_view = color_texture.create_view(&wgpu::TextureViewDescriptor::default());
+
+        let depth_texture = device.create_texture(&wgpu::TextureDescriptor {
+            label: Some("Viewport Depth"),
+            size: wgpu::Extent3d {
+                width: w,
+                height: h,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: VIEWPORT_DEPTH_FORMAT,
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
+            view_formats: &[],
+        });
+        let depth_view = depth_texture.create_view(&wgpu::TextureViewDescriptor::default());
+
+        ViewportTexture {
+            color_texture,
+            color_view,
+            depth_texture,
+            depth_view,
+            width: w,
+            height: h,
+        }
+    }
+
+    pub fn ensure_size(&mut self, device: &wgpu::Device, width: u32, height: u32) -> bool {
+        let w = width.max(1);
+        let h = height.max(1);
+        if w == self.width && h == self.height {
+            return false;
+        }
+        *self = Self::new(device, w, h);
+        true
+    }
+}