Merge #367

367: Support rendering to the swapchain from multiple command buffers r=jazzay a=kvark

Fixes #366

Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>

wgpu-native/src/device.rs

@@ -1571,22 +1571,20 @@ pub fn queue_submit<B: GfxBackend>(
             let comb = &mut command_buffer_guard[cmb_id];
 
             if let Some((view_id, fbo)) = comb.used_swap_chain.take() {
-                let sem = match texture_view_guard[view_id.value].inner {
+                match texture_view_guard[view_id.value].inner {
                     resource::TextureViewInner::Native { .. } => unreachable!(),
                     resource::TextureViewInner::SwapChain {
                         ref source_id,
-                        ref mut framebuffer,
+                        ref mut framebuffers,
                         ..
                     } => {
-                        assert!(
-                            framebuffer.is_none(),
-                            "Using a swap chain in multiple framebuffers is not supported yet"
-                        );
-                        *framebuffer = Some(fbo);
-                        &swap_chain_guard[source_id.value].semaphore
+                        if framebuffers.is_empty() {
+                            let sem = &swap_chain_guard[source_id.value].semaphore;
+                            signal_semaphores.push(sem);
+                        }
+                        framebuffers.push(fbo);
                     }
                 };
-                signal_semaphores.push(sem);
             }
 
             // optimize the tracked states

wgpu-native/src/resource.rs

@@ -18,6 +18,7 @@ use crate::{
 use bitflags::bitflags;
 use hal;
 use rendy_memory::MemoryBlock;
+use smallvec::SmallVec;
 
 use std::borrow::Borrow;
 
@@ -274,9 +275,7 @@ pub(crate) enum TextureViewInner<B: hal::Backend> {
     SwapChain {
         image: <B::Surface as hal::window::PresentationSurface<B>>::SwapchainImage,
         source_id: Stored<SwapChainId>,
-        //Note: limited to a single framebuffer, could be relaxed
-        // to support multiple ones.
-        framebuffer: Option<B::Framebuffer>,
+        framebuffers: SmallVec<[B::Framebuffer; 1]>,
     },
 }
 

wgpu-native/src/swap_chain.rs

@@ -50,9 +50,12 @@ use crate::{gfx_select, hub::GLOBAL};
 
 use hal::{self, device::Device as _, queue::CommandQueue as _, window::PresentationSurface as _};
 
+use smallvec::SmallVec;
+
 #[cfg(feature = "local")]
 use std::marker::PhantomData;
 
+
 const FRAME_TIMEOUT_MS: u64 = 1000;
 pub const DESIRED_NUM_FRAMES: u32 = 3;
 
@@ -173,7 +176,7 @@ pub fn swap_chain_get_next_texture<B: GfxBackend>(
                 value: swap_chain_id,
                 ref_count: sc.life_guard.ref_count.clone(),
             },
-            framebuffer: None,
+            framebuffers: SmallVec::new(),
         },
         format: sc.desc.format,
         extent: hal::image::Extent {
@@ -229,11 +232,11 @@ pub fn swap_chain_present<B: GfxBackend>(global: &Global, swap_chain_id: SwapCha
         .take()
         .expect("Swap chain image is not acquired");
     let (view, _) = hub.texture_views.unregister(view_id.value, &mut token);
-    let (image, framebuffer) = match view.inner {
+    let (image, framebuffers) = match view.inner {
         resource::TextureViewInner::Native { .. } => unreachable!(),
         resource::TextureViewInner::SwapChain {
-            image, framebuffer, ..
-        } => (image, framebuffer),
+            image, framebuffers, ..
+        } => (image, framebuffers),
     };
 
     let err = unsafe {
@@ -244,7 +247,7 @@ pub fn swap_chain_present<B: GfxBackend>(global: &Global, swap_chain_id: SwapCha
         log::warn!("present failed: {:?}", e);
     }
 
-    if let Some(fbo) = framebuffer {
+    for fbo in framebuffers {
         unsafe {
             device.raw.destroy_framebuffer(fbo);
         }