diff --git a/blog/2025-03-30-draw-compute-shader/draw-compute/shader/src/lib.rs b/blog/2025-03-30-draw-compute-shader/draw-compute/shader/src/lib.rs
index 10b25d4..77386e2 100644
--- a/blog/2025-03-30-draw-compute-shader/draw-compute/shader/src/lib.rs
+++ b/blog/2025-03-30-draw-compute-shader/draw-compute/shader/src/lib.rs
@@ -54,12 +54,16 @@ pub fn main_fs(
     #[spirv(storage_buffer, descriptor_set = 0, binding = 1)] image: &mut [glam::Vec4],
     output: &mut glam::Vec4,
 ) {
-    let pixel_coordinate = frag_coord.xy().as_usizevec2();
-    let (pixel_x, pixel_y) = (pixel_coordinate.x, pixel_coordinate.y);
+    let vp_size = viewport.size.as_vec2();
+    let img_size = viewport.image.as_vec2();
 
-    *output = if pixel_x < viewport.image.x as usize && pixel_y < viewport.image.y as usize {
-        image[image_index(pixel_x, pixel_y, viewport.image.x as usize)]
+    let scale = (vp_size / img_size).min_element();
+    let img_offset = (vp_size / scale - img_size) / 2.0;
+    let img_coord = (frag_coord.xy() - viewport.offset.as_vec2()) / scale - img_offset;
+
+    *output = if img_coord.cmpge(glam::Vec2::ZERO).all() && img_coord.cmple(img_size).all() {
+        image[image_index(img_coord.x as usize, img_coord.y as usize, viewport.image.x as usize)]
     } else {
         BLACK
-    };
+    }
 }
diff --git a/blog/2025-03-30-draw-compute-shader/draw-compute/src/main.rs b/blog/2025-03-30-draw-compute-shader/draw-compute/src/main.rs
index 9d32b2b..c67686f 100644
--- a/blog/2025-03-30-draw-compute-shader/draw-compute/src/main.rs
+++ b/blog/2025-03-30-draw-compute-shader/draw-compute/src/main.rs
@@ -172,6 +172,7 @@ impl DrawResources {
 
     fn resize(&mut self, width: u64, height: u64) {
         self.image_buffer = Self::image_buffer(&self.device, width, height);
+        self.image_size = glam::uvec2(width as u32, height as u32);
         self.bind_group = Self::bind_group(
             &self.device,
             &self.bind_group_layout,
@@ -206,7 +207,7 @@ impl CallbackTrait for DrawCallback {
             );
         }
 
-        let mut viewport = shader::Viewport {
+        let viewport = shader::Viewport {
             image: resources.image_size,
             offset: glam::uvec2(self.draw_rect.min.x as u32, self.draw_rect.min.y as u32),
             size: glam::uvec2(
@@ -273,6 +274,13 @@ impl eframe::App for ComputeDraw {
             callback_resources.insert(DrawResources::new(&device, &format, 800, 600));
         }
 
+        egui::TopBottomPanel::bottom("bottom").show(ctx, |ui| {
+            let wgpu_render_state = frame.wgpu_render_state().expect("missing WGPU state");
+            let image_size = wgpu_render_state.renderer.as_ref().read().callback_resources.get::<DrawResources>().unwrap().image_size;
+
+            ui.label(format!("Viewport: image={image_size}"))
+        });
+
         egui::CentralPanel::default().show(ctx, |ui| {
             egui::Frame::canvas(ui.style()).show(ui, |ui| {
                 let interact_rect = ui.available_rect_before_wrap();
@@ -301,7 +309,7 @@ fn main() {
     eframe::run_native(
         "Compute Draw",
         native_options,
-        Box::new(|cc| Ok(Box::new(ComputeDraw { initial_draw: true }))),
+        Box::new(|_cc| Ok(Box::new(ComputeDraw { initial_draw: true }))),
     )
     .unwrap()
 }