From: Matthew Schwartz <matthew.schwartz@linux.dev>
Subject: Lazily allocate shared Vulkan output images
Origin: upstream, commit e383171ff1c0f7b5b37f05f2bb67f7c5282b087f

Backport the upstream lazy-allocation change to Gamescope 3.16.20. Native
Wayland presentation normally sends the game's DMA-BUF directly to the host
compositor, so allocating six output-sized Vulkan images at startup and after
every host-window configure is unnecessary. Allocate those images only if a
frame actually needs full Vulkan composition.

--- a/src/rendervulkan.cpp
+++ b/src/rendervulkan.cpp
@@ -3345,6 +3345,31 @@ static bool vulkan_make_output_images( VulkanOutput_t *pOutput )
 	return true;
 }
 
+// Without a swapchain the shared images are ours to make, so they wait for their first use.
+static bool vulkan_defer_output_images()
+{
+	return !GetBackend()->UsesVulkanSwapchain();
+}
+
+static bool vulkan_ensure_output_images()
+{
+	if ( !vulkan_defer_output_images() )
+		return true;
+
+	VulkanOutput_t *pOutput = &g_output;
+	if ( !pOutput->outputImages.empty() && pOutput->outputImages[0] )
+		return true;
+
+	vk_log.debugf( "Making the shared output images on first use" );
+	if ( vulkan_make_output_images( pOutput ) )
+		return true;
+
+	// A half-made set would pass the check above, so the next use tries again from nothing.
+	pOutput->outputImages.clear();
+	pOutput->outputImagesPartialOverlay.clear();
+	return false;
+}
+
 bool vulkan_remake_output_images()
 {
 	VulkanOutput_t *pOutput = &g_output;
@@ -3355,6 +3380,14 @@ bool vulkan_remake_output_images()
 	for (auto& pScreenshotImage : pOutput->pScreenshotImages)
 		pScreenshotImage = nullptr;
 
+	if ( vulkan_defer_output_images() )
+	{
+		pOutput->outputImages.clear();
+		pOutput->outputImagesPartialOverlay.clear();
+		pOutput->temporaryHackyBlankImage = vulkan_create_debug_blank_texture();
+		return true;
+	}
+
 	bool bRet = vulkan_make_output_images( pOutput );
 	assert( bRet );
 	return bRet;
@@ -3433,7 +3466,9 @@ bool vulkan_make_output()
 			return false;
 		}
 
-		if ( !vulkan_make_output_images( pOutput ) )
+		if ( vulkan_defer_output_images() )
+			pOutput->temporaryHackyBlankImage = vulkan_create_debug_blank_texture();
+		else if ( !vulkan_make_output_images( pOutput ) )
 			return false;
 	}
 
@@ -3980,6 +4015,9 @@ std::optional<uint64_t> vulkan_composite( struct FrameInfo_t *frameInfo, gamesco
 		g_reshadeManager.clear();
 	}
 
+	if ( !pOutputOverride && !vulkan_ensure_output_images() )
+		return std::nullopt;
+
 	gamescope::Rc<CVulkanTexture> compositeImage;
 	if ( pOutputOverride )
 		compositeImage = pOutputOverride;