Towards fixing everything.

Most importantly these issues: KhronosGroup/Vulkan-ValidationLayers#6177

auto_vk_toolkit/include/imgui_manager.hpp

@@ -25,6 +25,7 @@ namespace avk
 			, mQueue { &aQueueToSubmitTo }
 			, mUserInteractionEnabled{ true }
 			, mAlterSettingsBeforeInitialization{ std::move(aAlterSettingsBeforeInitialization) }
+			, mIncomingLayout{ layout::color_attachment_optimal }
 		{
 			if (aRenderpassToUse.has_value()) {
 				mRenderpass = std::move(aRenderpassToUse.value());
@@ -126,6 +127,24 @@ namespace avk
 		bool end_wanting_to_occupy_mouse() const {
 			return !mOccupyMouse && mOccupyMouseLastFrame;
 		}
+
+		/** Gets the image layout that imgui_manager assumes the color attachment to be in when it starts
+		 *  to render into it.
+		 *	The default value is: avk::layout::color_attachment_optimal
+		 */
+		layout::image_layout previous_image_layout() const {
+			return mIncomingLayout;
+		}
+
+		/** Sets the image layout that imgui_manager shall expect the color attachment to be in
+		 *  before starting to render into it.
+		 *	Note: This change might only have effect BEFORE imgui_manager has been initialized,
+		 *	      i.e., before its ::initialize() method has been invoked by the framework for the
+		 *		  first time. => Ensure to configure this value before starting the composition!
+		 */
+		void set_previous_image_layout(layout::image_layout aIncomingLayout) {
+			mIncomingLayout = aIncomingLayout;
+		}
 	private:
 		void upload_fonts();
 		void construct_render_pass();
@@ -156,6 +175,7 @@ namespace avk
 		// customization
 		std::function<void(float)> mAlterSettingsBeforeInitialization = {};
 		std::string mCustomTtfFont = {};
+		layout::image_layout mIncomingLayout;
 	};
 
 }

auto_vk_toolkit/src/imgui_manager.cpp

@@ -522,7 +522,7 @@ namespace avk
 
 		auto* wnd = context().main_window();
 		std::vector<attachment> attachments;
-		attachments.push_back(attachment::declare(format_from_window_color_buffer(wnd), on_load::load, usage::color(0), on_store::store.in_layout(layout::present_src)));
+		attachments.push_back(attachment::declare(format_from_window_color_buffer(wnd), on_load::load.from_previous_layout(mIncomingLayout), usage::color(0), on_store::store.in_layout(layout::present_src)));
 		for (auto a : wnd->get_additional_back_buffer_attachments()) {
 			// Well... who would have guessed the following (and, who understands??):
 			//
@@ -544,13 +544,13 @@ namespace avk
 				subpass_dependency(
 					subpass::external >> subpass::index(0),
 					// ... we have to synchronize all these stages with color+dept_stencil write access:
-					stage::color_attachment_output | stage::early_fragment_tests | stage::late_fragment_tests >> stage::color_attachment_output | stage::early_fragment_tests | stage::late_fragment_tests,
-					access::color_attachment_write | access::depth_stencil_attachment_write >> access::color_attachment_read | access::depth_stencil_attachment_write
+					stage::color_attachment_output   >>   stage::color_attachment_output,
+					access::none                     >>   access::color_attachment_read | access::color_attachment_write // read && write due to layout transition
 				),
 				subpass_dependency(
 					subpass::index(0) >> subpass::external,
-					stage::color_attachment_output >> stage::none, // assume semaphore afterwards
-					access::color_attachment_write >> access::none
+					stage::color_attachment_output   >>   stage::color_attachment_output,  // assume semaphore afterwards
+					access::color_attachment_write   >>   access::none                     //  ^ ...but still, gotta synchronize image layout transition with subsequent presentKHR :ohgodwhy:
 				)
 			}
 		);
@@ -562,13 +562,13 @@ namespace avk
 			, {
 				subpass_dependency(
 					subpass::external >> subpass::index(0),
-					stage::none >> stage::color_attachment_output,
-					access::none >> access::color_attachment_read | access::color_attachment_write
+					stage::color_attachment_output   >>   stage::color_attachment_output,
+					access::none                     >>   access::color_attachment_read | access::color_attachment_write // read && write due to layout transition
 				),
 				subpass_dependency(
 					subpass::index(0) >> subpass::external,
-					stage::color_attachment_output >> stage::none, // assume semaphore afterwards
-					access::color_attachment_write >> access::none
+					stage::color_attachment_output >> stage::color_attachment_output,  // assume semaphore afterwards
+					access::color_attachment_write >> access::none                     //  ^ ...but still, gotta synchronize image layout transition with subsequent presentKHR :ohgodwhy:
 				)
 			}
 		);

auto_vk_toolkit/src/window.cpp

@@ -834,12 +834,12 @@ namespace avk
 			auto newRenderPass = context().create_renderpass(renderpassAttachments, {
 				// We only create one subpass here => create default dependencies as per specification chapter 8.1) Render Pass Creation:
 				avk::subpass_dependency{avk::subpass::external >> avk::subpass::index(0),
-					avk::stage::none  >> avk::stage::all_graphics,
-					avk::access::none >> avk::access::input_attachment_read | avk::access::color_attachment_read | avk::access::color_attachment_write | avk::access::depth_stencil_attachment_read | avk::access::depth_stencil_attachment_write
+					stage::color_attachment_output    >>   stage::early_fragment_tests | stage::late_fragment_tests | stage::color_attachment_output,
+					access::none                      >>   access::color_attachment_read | access::color_attachment_write | access::depth_stencil_attachment_read | access::depth_stencil_attachment_write
 				},
 				avk::subpass_dependency{avk::subpass::index(0) >> avk::subpass::external,
-					avk::stage::all_graphics                                                          >> avk::stage::none,
-					avk::access::color_attachment_write | avk::access::depth_stencil_attachment_write >> avk::access::none
+					stage::color_attachment_output    >>   stage::color_attachment_output,
+					access::color_attachment_write    >>   access::none
 				}
 			});
 			if (mBackBufferRenderpass.has_value() && mBackBufferRenderpass.is_shared_ownership_enabled()) {

examples/framebuffer/source/framebuffer.cpp

@@ -223,12 +223,12 @@ class framebuffer_app : public avk::invokee
 				// Transition the layouts before performing the transfer operation:
 				avk::sync::image_memory_barrier(mOneFramebuffer->image_at(mSelectedAttachmentToCopy),
 					// None here, because we're synchronizing with a semaphore
-					avk::stage::none  >> avk::stage::copy | avk::stage::blit,
-					avk::access::none >> avk::access::transfer_read
+					avk::stage::color_attachment_output  >> avk::stage::copy | avk::stage::blit,
+					avk::access::color_attachment_write  >> avk::access::transfer_read
 				).with_layout_transition(sourceImageLayout >> avk::layout::transfer_src),
 				avk::sync::image_memory_barrier(mainWnd->current_backbuffer()->image_at(0),
-					avk::stage::none  >> avk::stage::copy | avk::stage::blit,
-					avk::access::none >> avk::access::transfer_write
+					avk::stage::color_attachment_output  >> avk::stage::copy | avk::stage::blit,
+					avk::access::color_attachment_write  >> avk::access::transfer_write
 				).with_layout_transition(avk::layout::undefined >> avk::layout::transfer_dst),
 
 				// Perform the transfer operation:

examples/hello_world/source/hello_world.cpp

@@ -160,7 +160,7 @@ int main() // <== Starting point ==
 		auto composition = configure_and_compose(
 			avk::application_name("Hello, Auto-Vk-Toolkit World!"),
 			[](avk::validation_layers& config) {
-				//config.enable_feature(vk::ValidationFeatureEnableEXT::eSynchronizationValidation);
+				config.enable_feature(vk::ValidationFeatureEnableEXT::eSynchronizationValidation);
 			},
 			// Pass windows:
 			mainWnd,

examples/model_loader/source/model_loader.cpp

@@ -466,7 +466,7 @@ int main() // <== Starting point ==
 		auto composition = configure_and_compose(
 			avk::application_name("Auto-Vk-Toolkit Example: Model Loader"),
 			[](avk::validation_layers& config) {
-				//config.enable_feature(vk::ValidationFeatureEnableEXT::eSynchronizationValidation);
+				config.enable_feature(vk::ValidationFeatureEnableEXT::eSynchronizationValidation);
 			},
 			// Pass windows:
 			mainWnd,