Render Texture Extraction

1 files changed, 65 insertions, 0 deletions

diff --git a/src/systems.rs b/src/systems.rs
new file mode 100644
index 0000000..25b25dc
--- /dev/null
+++ b/src/systems.rs
@@ -0,0 +1,65 @@
+use std::time::Duration;
+
+use bevy::{prelude::*, render::{render_asset::{RenderAssets, RenderAssetUsages}, renderer::RenderDevice, render_resource::{MapMode, Maintain, Extent3d, TextureDimension}}};
+
+use pollster::FutureExt;
+
+use crate::{render_assets::FramebufferExtractSource, components::FramebufferExtractDestination};
+
+pub fn extract_framebuffers(
+    mut extract_bundles: Query<(&Handle<FramebufferExtractSource>, &mut FramebufferExtractDestination)>, 
+    sources: Res<RenderAssets<FramebufferExtractSource>>,
+    device: Res<RenderDevice>,
+) {
+    for (source_handle, destination_handle) in extract_bundles.iter_mut() {
+        let Some(gpu_source) = sources.get(source_handle) else {
+            continue;
+        };
+
+        let mut image_bytes = {
+            let slice = gpu_source.buffer.slice(..);
+
+            {
+                let (tx, rx) = oneshot::channel();
+                device.map_buffer(&slice, MapMode::Read, move |res| {
+                    tx.send(res).unwrap();
+                });
+                device.poll(Maintain::Wait);
+                rx.block_on().unwrap().unwrap();
+            }
+             
+            slice.get_mapped_range().to_vec()
+        };
+
+        gpu_source.buffer.unmap();
+
+        let bytes_per_row = gpu_source.bytes_per_row as usize;
+        let padded_bytes_per_row = gpu_source.padded_bytes_per_row as usize;
+        let source_size = gpu_source.source_size;
+        let destination_handle = destination_handle.clone();
+        let source_format = gpu_source.format;
+
+        std::thread::spawn(move || {
+            if bytes_per_row != padded_bytes_per_row {
+                let mut unpadded_bytes = Vec::<u8>::with_capacity(source_size.height as usize * bytes_per_row);
+                for padded_row in image_bytes.chunks(padded_bytes_per_row) {
+                    unpadded_bytes.extend_from_slice(&padded_row[..bytes_per_row]);
+                }
+                image_bytes = unpadded_bytes;
+            }
+
+            *destination_handle.0.lock().unwrap() = Image::new(
+                Extent3d {
+                    width: source_size.width,
+                    height: source_size.height,
+                    depth_or_array_layers: 1,
+                },
+                TextureDimension::D2,
+                image_bytes,
+                source_format,
+                RenderAssetUsages::MAIN_WORLD | RenderAssetUsages::RENDER_WORLD,
+            );
+        });
+    }
+
+}