Rework UI overlay initialization

Author: SaschaWillems

base/VulkanUIOverlay.cpp

@@ -2,7 +2,7 @@
 /*
 * UI overlay class using ImGui
 *
-* Copyright (C) 2017-2025 by Sascha Willems - www.saschawillems.de
+* Copyright (C) 2017-2026 by Sascha Willems - www.saschawillems.de
 *
 * This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
 */
@@ -56,7 +56,7 @@ namespace vks
 	}
 
 	/** Prepare all vulkan resources required to render the UI overlay */
-	void UIOverlay::prepareResources()
+	void UIOverlay::prepare()
 	{
 		assert(maxConcurrentFrames > 0);
 
@@ -192,11 +192,7 @@ namespace vks
 
 		// Buffers per max. frames-in-flight
 		buffers.resize(maxConcurrentFrames);
-	}
 
-	/** Prepare a separate pipeline for the UI overlay rendering decoupled from the main application */
-	void UIOverlay::preparePipeline(const VkPipelineCache pipelineCache, const VkRenderPass renderPass, const VkFormat colorFormat, const VkFormat depthFormat)
-	{
 		// Pipeline layout
 		// Push constants for UI rendering parameters
 		VkPushConstantRange pushConstantRange{ .stageFlags = VK_SHADER_STAGE_VERTEX_BIT, .size = sizeof(PushConstBlock) };
@@ -276,7 +272,7 @@ namespace vks
 			pipelineCreateInfo.pNext = &pipelineRenderingCreateInfo;
 		}
 #endif
-		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device->logicalDevice, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipeline));
+		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device->logicalDevice, VK_NULL_HANDLE, 1, &pipelineCreateInfo, nullptr, &pipeline));
 	}
 
 	/** Update vertex and index buffer containing the imGui elements when required */

base/VulkanUIOverlay.h

@@ -1,7 +1,7 @@
 /*
 * UI overlay class using ImGui
 *
-* Copyright (C) 2017-2025 by Sascha Willems - www.saschawillems.de
+* Copyright (C) 2017-2026 by Sascha Willems - www.saschawillems.de
 *
 * This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
 */
@@ -74,11 +74,14 @@ namespace vks
 		bool visible{ true };
 		float scale{ 1.0f };
 
+		VkRenderPass renderPass{ VK_NULL_HANDLE };
+		VkFormat colorFormat{ VK_FORMAT_UNDEFINED };
+		VkFormat depthFormat{ VK_FORMAT_UNDEFINED };
+
 		UIOverlay();
 		~UIOverlay();
 
-		void preparePipeline(const VkPipelineCache pipelineCache, const VkRenderPass renderPass, const VkFormat colorFormat, const VkFormat depthFormat);
-		void prepareResources();
+		void prepare();
 
 		void update(uint32_t currentBuffer);
 		void draw(const VkCommandBuffer commandBuffer, uint32_t currentBuffer);

base/vulkanexamplebase.cpp

@@ -239,12 +239,14 @@ void VulkanExampleBase::prepare()
 		ui.maxConcurrentFrames = maxConcurrentFrames;
 		ui.device = vulkanDevice;
 		ui.queue = queue;
+		ui.renderPass = renderPass;
+		ui.colorFormat = swapChain.colorFormat;
+		ui.depthFormat = depthFormat;
 		ui.shaders = {
 			loadShader(getShadersPath() + "base/uioverlay.vert.spv", VK_SHADER_STAGE_VERTEX_BIT),
 			loadShader(getShadersPath() + "base/uioverlay.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT),
 		};
-		ui.prepareResources();
-		ui.preparePipeline(pipelineCache, renderPass, swapChain.colorFormat, depthFormat);
+		ui.prepare();
 	}
 }