From 60321d465aaa6137f57c70d1dfba33aabdae6813 Mon Sep 17 00:00:00 2001
From: Sascha Willems <webmaster@saschawillems.de>
Date: Sat, 14 Oct 2023 16:35:41 +0200
Subject: [PATCH] Proper resize handling

---
 .../variablerateshading.cpp                   | 33 +++++++++++--------
 .../variablerateshading/variablerateshading.h |  3 +-
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/examples/variablerateshading/variablerateshading.cpp b/examples/variablerateshading/variablerateshading.cpp
index 50f66300..fe41b4e8 100644
--- a/examples/variablerateshading/variablerateshading.cpp
+++ b/examples/variablerateshading/variablerateshading.cpp
@@ -47,21 +47,33 @@ void VulkanExample::getEnabledFeatures()
 }
 
 /*
-	If the window has been resized, we need to recreate the shading rate image
+	If the window has been resized, we need to recreate the shading rate image and the render pass. That's because the render pass holds information on the fragment shading rate image resolution
+	
 */
 void VulkanExample::handleResize()
 {
-	// Delete allocated resources
+	vkDeviceWaitIdle(device);
+	// Invalidate the shading rate image, will be recreated in the renderpass setup
 	vkDestroyImageView(device, shadingRateImage.view, nullptr);
 	vkDestroyImage(device, shadingRateImage.image, nullptr);
 	vkFreeMemory(device, shadingRateImage.memory, nullptr);
-	// Recreate image
 	prepareShadingRateImage();
+	// Recreate the render pass and update it with the new fragment shading rate image resolution
+	vkDestroyRenderPass(device, renderPass, nullptr);
+	setupRenderPass();
 	resized = false;
 }
 
 void VulkanExample::setupFrameBuffer()
 {
+	if (resized) {
+		handleResize();
+	}
+
+	if (shadingRateImage.image == VK_NULL_HANDLE) {
+		prepareShadingRateImage();
+	}
+
 	VkImageView attachments[3];
 
 	// Depth/Stencil attachment is the same for all frame buffers
@@ -94,8 +106,9 @@ void VulkanExample::setupRenderPass()
 		vkCreateRenderPass2KHR = reinterpret_cast<PFN_vkCreateRenderPass2KHR>(vkGetInstanceProcAddr(instance, "vkCreateRenderPass2KHR"));
 	}
 
-	// Create an image with the shading rates to be used during rendering
-	prepareShadingRateImage();
+	if (shadingRateImage.image == VK_NULL_HANDLE) {
+		prepareShadingRateImage();
+	}
 
 	std::array<VkAttachmentDescription2KHR, 3> attachments = {};
 	// Color attachment
@@ -202,11 +215,6 @@ void VulkanExample::setupRenderPass()
 
 void VulkanExample::buildCommandBuffers()
 {
-	if (resized)
-	{
-		handleResize();
-	}
-
 	// As this is an extension, we need to manually load the extension pointers
 	if (!vkCmdSetFragmentShadingRateKHR) {
 		vkCmdSetFragmentShadingRateKHR = reinterpret_cast<PFN_vkCmdSetFragmentShadingRateKHR>(vkGetDeviceProcAddr(device, "vkCmdSetFragmentShadingRateKHR"));
@@ -538,14 +546,11 @@ void VulkanExample::preparePipelines()
 	};
 	VkSpecializationInfo specializationInfo = vks::initializers::specializationInfo(specializationMapEntries, sizeof(specializationData), &specializationData);
 	shaderStages[1].pSpecializationInfo = &specializationInfo;
-
-	// Create pipeline without shading rate 
 	VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.opaque));
+
 	specializationData.alphaMask = true;
 	rasterizationStateCI.cullMode = VK_CULL_MODE_NONE;
 	VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCI, nullptr, &pipelines.masked));
-	rasterizationStateCI.cullMode = VK_CULL_MODE_BACK_BIT;
-	specializationData.alphaMask = false;
 }
 
 void VulkanExample::prepareUniformBuffers()
diff --git a/examples/variablerateshading/variablerateshading.h b/examples/variablerateshading/variablerateshading.h
index c634bcf3..9d2167c8 100644
--- a/examples/variablerateshading/variablerateshading.h
+++ b/examples/variablerateshading/variablerateshading.h
@@ -17,7 +17,7 @@ public:
 	vkglTF::Model scene;
 
 	struct ShadingRateImage {
-		VkImage image;
+		VkImage image{ VK_NULL_HANDLE };
 		VkDeviceMemory memory;
 		VkImageView view;
 	} shadingRateImage;
@@ -58,7 +58,6 @@ public:
 	virtual void getEnabledFeatures();
 	void handleResize();
 	void buildCommandBuffers();
-	void loadglTFFile(std::string filename);
 	void loadAssets();
 	void prepareShadingRateImage();
 	void setupDescriptors();