From c8554b59d4a398f958b33fa94013c5cfa8b4b515 Mon Sep 17 00:00:00 2001
From: Sven Niederberger <s-niederberger@outlook.com>
Date: Mon, 14 Jul 2025 16:00:47 +0200
Subject: [PATCH] update the example

---
 examples/shader/gpu_readback.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/examples/shader/gpu_readback.rs b/examples/shader/gpu_readback.rs
index 964776291e..7766db5e8b 100644
--- a/examples/shader/gpu_readback.rs
+++ b/examples/shader/gpu_readback.rs
@@ -74,7 +74,7 @@ fn setup(
     mut buffers: ResMut<Assets<ShaderStorageBuffer>>,
 ) {
     // Create a storage buffer with some data
-    let buffer = vec![0u32; BUFFER_LEN];
+    let buffer: Vec<u32> = (0..BUFFER_LEN as u32).collect();
     let mut buffer = ShaderStorageBuffer::from(buffer);
     // We need to enable the COPY_SRC usage so we can copy the buffer to the cpu
     buffer.buffer_description.usage |= BufferUsages::COPY_SRC;
@@ -110,6 +110,19 @@ fn setup(
             let data: Vec<u32> = trigger.event().to_shader_type();
             info!("Buffer {:?}", data);
         });
+
+    // It is also possible to read only a range of the buffer.
+    commands
+        .spawn(Readback::buffer_range(
+            buffer.clone(),
+            4 * u32::SHADER_SIZE.get(), // skip the first four elements
+            8 * u32::SHADER_SIZE.get(), // read eight elements
+        ))
+        .observe(|trigger: On<ReadbackComplete>| {
+            let data: Vec<u32> = trigger.event().to_shader_type();
+            info!("Buffer range {:?}", data);
+        });
+
     // This is just a simple way to pass the buffer handle to the render app for our compute node
     commands.insert_resource(ReadbackBuffer(buffer));