RHI: fix Vulkan layout for PreserveDepthStencilContents depth textures

Vulkan fails when we attach a depth texture to a render target with
QRhiTextureRenderTarget::PreserveDepthStencilContents (we want to reuse
the depth data from a depth pre-pass.)

vkCreateRenderPass(): pCreateInfo->pAttachments[3] format is
VK_FORMAT_D32_SFLOAT and loadOp is VK_ATTACHMENT_LOAD_OP_LOAD, but
initialLayout is VK_IMAGE_LAYOUT_UNDEFINED.
The Vulkan spec states: If format includes a color or depth component
and loadOp is VK_ATTACHMENT_LOAD_OP_LOAD, then initialLayout must not be
VK_IMAGE_LAYOUT_UNDEFINED (https://www.khronos.org/registry/vulkan/
specs/1.3-extensions/html/vkspec.html#VUID-VkAttachmentDescription-
format-06699)

To fix this, just do the same as color attachments: specify a
VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL instead of
VK_IMAGE_LAYOUT_UNDEFINED when the depth-stencil is preserved.

[ChangeLog][RHI] QRhiTextureRenderTarget::PreserveDepthStencilContents
now works properly on Vulkan

Pick-to: 6.7
Change-Id: I0577bc8021b3598ddfdcea4af98aaef46e8a4519
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gui/rhi/qrhivulkan.cpp b/src/gui/rhi/qrhivulkan.cpp
index 111fefe7a9..4d7b361f80 100644
--- a/src/gui/rhi/qrhivulkan.cpp
+++ b/src/gui/rhi/qrhivulkan.cpp
@@ -1494,7 +1494,7 @@ bool QRhiVulkan::createOffscreenRenderPass(QVkRenderPassDescriptor *rpD,
         attDesc.storeOp = storeOp;
         attDesc.stencilLoadOp = loadOp;
         attDesc.stencilStoreOp = storeOp;
-        attDesc.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+        attDesc.initialLayout = preserveDs ? VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL : VK_IMAGE_LAYOUT_UNDEFINED;
         attDesc.finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
         rpD->attDescs.append(attDesc);
     }