Add support for reading from a mapped buffer.

bevyengine · Jan 21, 2021 · 805190b · 805190b
1 parent dc52ef3
commit 805190b
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Showing 3 changed files with 32 additions and 0 deletions.
diff --git a/crates/bevy_render/src/renderer/headless_render_resource_context.rs b/crates/bevy_render/src/renderer/headless_render_resource_context.rs
@@ -66,6 +66,17 @@ impl RenderResourceContext for HeadlessRenderResourceContext {
         write(&mut buffer, self);
     }
 
+    fn read_mapped_buffer(
+        &self,
+        id: BufferId,
+        _range: Range<u64>,
+        read: &dyn Fn(&[u8], &dyn RenderResourceContext),
+    ) {
+        let size = self.buffer_info.read().get(&id).unwrap().size;
+        let buffer = vec![0; size];
+        read(&buffer, self);
+    }
+
     fn map_buffer(&self, _id: BufferId, _mode: BufferMapMode) {}
 
     fn unmap_buffer(&self, _id: BufferId) {}

diff --git a/crates/bevy_render/src/renderer/render_resource_context.rs b/crates/bevy_render/src/renderer/render_resource_context.rs
@@ -24,6 +24,12 @@ pub trait RenderResourceContext: Downcast + Send + Sync + 'static {
         range: Range<u64>,
         write: &mut dyn FnMut(&mut [u8], &dyn RenderResourceContext),
     );
+    fn read_mapped_buffer(
+        &self,
+        id: BufferId,
+        range: Range<u64>,
+        read: &dyn Fn(&[u8], &dyn RenderResourceContext),
+    );
     fn map_buffer(&self, id: BufferId, mode: BufferMapMode);
     fn unmap_buffer(&self, id: BufferId);
     fn create_buffer_with_data(&self, buffer_info: BufferInfo, data: &[u8]) -> BufferId;

diff --git a/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs b/crates/bevy_wgpu/src/renderer/wgpu_render_resource_context.rs
@@ -622,6 +622,21 @@ impl RenderResourceContext for WgpuRenderResourceContext {
         write(&mut data, self);
     }
 
+    fn read_mapped_buffer(
+        &self,
+        id: BufferId,
+        range: Range<u64>,
+        read: &dyn Fn(&[u8], &dyn RenderResourceContext),
+    ) {
+        let buffer = {
+            let buffers = self.resources.buffers.read();
+            buffers.get(&id).unwrap().clone()
+        };
+        let buffer_slice = buffer.slice(range);
+        let data = buffer_slice.get_mapped_range();
+        read(&data, self);
+    }
+
     fn map_buffer(&self, id: BufferId, mode: BufferMapMode) {
         let buffers = self.resources.buffers.read();
         let buffer = buffers.get(&id).unwrap();