From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 13 Aug 2024 12:14:49 +0000 (+0300)
Subject: Adjust the logic for discarding fraembuffer contents in Vulkan
X-Git-Url: https://git.tdb.fi/?a=commitdiff_plain;h=f69f21937213d8ffedaa35a2a3da6cbfaab5daab;p=libs%2Fgl.git

Adjust the logic for discarding fraembuffer contents in Vulkan

It was unnecessarily transitioning from a known layout when the
framebuffer is being cleraed.  This triggered a validation error on the
first frame when rendering directly to the swapchain.
---

diff --git a/source/backends/vulkan/renderpass.cpp b/source/backends/vulkan/renderpass.cpp
index 1c2af612..b6c09c23 100644
--- a/source/backends/vulkan/renderpass.cpp
+++ b/source/backends/vulkan/renderpass.cpp
@@ -53,18 +53,26 @@ void RenderPass::fill_creation_info(vector<char> &buffer) const
 	VkAttachmentReference2 *color_ptr = color_refs;
 	VkAttachmentReference2 *ds_ptr = depth_stencil_ref;
 	unsigned i = 0;
-	auto fill_attachment = [=, &color_ptr, &ds_ptr, &i](FrameAttachment a, VkSampleCountFlagBits samples, bool discard){
+	auto fill_attachment = [=, &color_ptr, &ds_ptr, &i](FrameAttachment a, VkSampleCountFlagBits samples, bool force_discard){
 		VkImageLayout subpass_layout = static_cast<VkImageLayout>(get_vulkan_attachment_layout(get_components(get_attachment_pixelformat(a))));
 		VkImageLayout external_layout = (to_present ? VK_IMAGE_LAYOUT_PRESENT_SRC_KHR : subpass_layout);
 
 		attachments[i].sType = VK_STRUCTURE_TYPE_ATTACHMENT_DESCRIPTION_2;
 		attachments[i].format = static_cast<VkFormat>(get_vulkan_pixelformat(get_attachment_pixelformat(a)));
 		attachments[i].samples = samples;
-		attachments[i].loadOp = (discard ? VK_ATTACHMENT_LOAD_OP_DONT_CARE : clear ? VK_ATTACHMENT_LOAD_OP_CLEAR : VK_ATTACHMENT_LOAD_OP_LOAD);
+		if(force_discard || (clear && !clear_values))
+			attachments[i].loadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+		else if(clear && clear_values)
+			attachments[i].loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+		else
+			attachments[i].loadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
 		attachments[i].storeOp = VK_ATTACHMENT_STORE_OP_STORE;
 		attachments[i].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
 		attachments[i].stencilStoreOp = VK_ATTACHMENT_STORE_OP_STORE;
-		attachments[i].initialLayout = (discard ? VK_IMAGE_LAYOUT_UNDEFINED : external_layout);
+		if(force_discard || discard_fb_contents)
+			attachments[i].initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+		else
+			attachments[i].initialLayout = external_layout;
 		attachments[i].finalLayout = external_layout;
 
 		if(subpass_layout==VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL)
@@ -84,10 +92,9 @@ void RenderPass::fill_creation_info(vector<char> &buffer) const
 		++i;
 	};
 
-	bool discard = (clear && !clear_values && discard_fb_contents);
 	VkSampleCountFlagBits vk_samples = static_cast<VkSampleCountFlagBits>(get_vulkan_samples(format.get_samples()));
 	for(FrameAttachment a: format)
-		fill_attachment(a, vk_samples, discard);
+		fill_attachment(a, vk_samples, false);
 
 	if(resolve)
 	{