From a8d3e74734f2b892824d361a7a0e7abe076ce1eb Mon Sep 17 00:00:00 2001
From: saschawillems <webmaster@saschawillems.de>
Date: Wed, 8 Jun 2016 22:41:29 +0200
Subject: [PATCH] Updated debug callback, added more message prefixes and some
 comments (also fixes

---
 base/vulkandebug.cpp       | 55 +++++++++++++++++++++++++++-----------
 base/vulkanexamplebase.cpp |  6 ++++-
 2 files changed, 45 insertions(+), 16 deletions(-)

diff --git a/base/vulkandebug.cpp b/base/vulkandebug.cpp
index 0b0b6ddd..333f5603 100644
--- a/base/vulkandebug.cpp
+++ b/base/vulkandebug.cpp
@@ -1,5 +1,7 @@
 /*
 * Vulkan examples debug wrapper
+* 
+* Appendix for VK_EXT_Debug_Report can be found at https://github.com/KhronosGroup/Vulkan-Docs/blob/1.0-VK_EXT_debug_report/doc/specs/vulkan/appendices/debug_report.txt
 *
 * Copyright (C) 2016 by Sascha Willems - www.saschawillems.de
 *
@@ -36,29 +38,52 @@ namespace vkDebug
 		const char* pMsg,
 		void* pUserData)
 	{
-		char *message = (char *)malloc(strlen(pMsg) + 100);
+		// Message text passed in by validation layer
+		std::string text(pMsg);
 
-		assert(message);
+		// Select prefix depending on flags passed to the callback
+		// Note that multiple flags may be set for a single validation message
+		std::string prefix("");
 
+		// Error that may result in undefined behaviour
 		if (flags & VK_DEBUG_REPORT_ERROR_BIT_EXT)
 		{
-			std::cout << "ERROR: " << "[" << pLayerPrefix << "] Code " << msgCode << " : " << pMsg << "\n";
+			prefix += "ERROR:";
+		};
+		// Warnings may hint at unexpected / non-spec API usage
+		if (flags & VK_DEBUG_REPORT_WARNING_BIT_EXT)
+		{
+			prefix += "WARNING:";
+		};
+		// May indicate sub-optimal usage of the API
+		if (flags & VK_DEBUG_REPORT_PERFORMANCE_WARNING_BIT_EXT)
+		{
+			prefix += "PERFORMANCE:";
+		};
+		// Informal messages that may become handy during debugging
+		if (flags & VK_DEBUG_REPORT_INFORMATION_BIT_EXT)
+		{
+			prefix += "INFO:";
 		}
-		else
-			if (flags & VK_DEBUG_REPORT_WARNING_BIT_EXT)
-			{
-				// Uncomment to see warnings
-				//std::cout << "WARNING: " << "[" << pLayerPrefix << "] Code " << msgCode << " : " << pMsg << "\n";
-			}
-			else
-			{
-				return false;
-			}
+		// Diagnostic info from the Vulkan loader and layers
+		// Usually not helpful in terms of API usage, but may help to debug layer and loader problems 
+		if (flags & VK_DEBUG_REPORT_DEBUG_BIT_EXT)
+		{
+			prefix += "DEBUG:";
+		}
+
+		// Display message to default output (console if activated)
+		std::cout << prefix << " [" << pLayerPrefix << "] Code " << msgCode << " : " << pMsg << "\n";
 
 		fflush(stdout);
 
-		free(message);
-		return false;
+		// The return value of this callback controls wether the Vulkan call that caused
+		// the validation message will be aborted or not
+		// We return VK_FALSE as we DON'T want Vulkan calls that cause a validation message 
+		// (and return a VkResult) to abort
+		// If you instead want to have calls abort, pass in VK_TRUE and the function will 
+		// return VK_ERROR_VALIDATION_FAILED_EXT 
+		return VK_FALSE;
 	}
 
 	void setupDebugging(VkInstance instance, VkDebugReportFlagsEXT flags, VkDebugReportCallbackEXT callBack)
diff --git a/base/vulkanexamplebase.cpp b/base/vulkanexamplebase.cpp
index ca942ef3..86b4a877 100644
--- a/base/vulkanexamplebase.cpp
+++ b/base/vulkanexamplebase.cpp
@@ -242,7 +242,11 @@ void VulkanExampleBase::prepare()
 {
 	if (enableValidation)
 	{
-		vkDebug::setupDebugging(instance, VK_DEBUG_REPORT_ERROR_BIT_EXT | VK_DEBUG_REPORT_WARNING_BIT_EXT, VK_NULL_HANDLE);
+		// The report flags determine what type of messages for the layers will be displayed
+		// For validating (debugging) an appplication the error and warning bits should suffice
+		VkDebugReportFlagsEXT debugReportFlags = VK_DEBUG_REPORT_ERROR_BIT_EXT; // VK_DEBUG_REPORT_WARNING_BIT_EXT (enable to also display warnings)
+		// Additional flags include performance info, loader and layer debug messages, etc.
+		vkDebug::setupDebugging(instance,  debugReportFlags, VK_NULL_HANDLE);
 	}
 	if (enableDebugMarkers)
 	{