From 459fa078e01586f1b9296fb75950fd4c0a9d2b9b Mon Sep 17 00:00:00 2001
From: John Zulauf <jzulauf@lunarg.com>
Date: Fri, 16 Oct 2020 18:34:06 -0600
Subject: [PATCH] Add subpass sync support for layout transitions

Add additional source and dest mask bits for "from external" and "to
external" subpass dependencies (respectively) when intial and final
layouts cause implicit layout transitions.

This is a big hammer -- any transition in a given direction will create
a full barrier.  Attachment specific stage and access flags could be
used instead with additional logic to deduce the prior and intended
subsequent usages.
---
 drivers/vulkan/rendering_device_vulkan.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/vulkan/rendering_device_vulkan.cpp b/drivers/vulkan/rendering_device_vulkan.cpp
index 72a0c128c2c..b051fe825c0 100644
--- a/drivers/vulkan/rendering_device_vulkan.cpp
+++ b/drivers/vulkan/rendering_device_vulkan.cpp
@@ -3218,6 +3218,18 @@ VkRenderPass RenderingDeviceVulkan::_render_pass_create(const Vector<AttachmentF
 		} else {
 			ERR_FAIL_V_MSG(VK_NULL_HANDLE, "Texture index " + itos(i) + " is neither color, depth stencil or resolve so it can't be used as attachment.");
 		}
+
+		// NOTE: Big Mallet Approach -- any layout transition causes a full barrier
+		if (reference.layout != description.initialLayout) {
+			// NOTE: this should be smarter based on the textures knowledge of it's previous role
+			dependency_from_external.srcStageMask |= VK_PIPELINE_STAGE_ALL_COMMANDS_BIT;
+			dependency_from_external.srcAccessMask |= VK_ACCESS_MEMORY_READ_BIT | VK_ACCESS_MEMORY_WRITE_BIT;
+		}
+		if (reference.layout != description.finalLayout) {
+			// NOTE: this should be smarter based on the textures knowledge of it's subsequent role
+			dependency_from_external.dstStageMask |= VK_PIPELINE_STAGE_ALL_COMMANDS_BIT;
+			dependency_from_external.dstAccessMask |= VK_ACCESS_MEMORY_READ_BIT | VK_ACCESS_MEMORY_WRITE_BIT;
+		}
 	}
 
 	ERR_FAIL_COND_V_MSG(depth_stencil_references.size() > 1, VK_NULL_HANDLE,