VkDebugUtilsMessengerCreateInfoEXT

The definition of VkDebugUtilsMessengerCreateInfoEXT is:

typedef struct VkDebugUtilsMessengerCreateInfoEXT {
    VkStructureType sType;
    const void* pNext;
    VkDebugUtilsMessengerCreateFlagsEXT flags;
    VkDebugUtilsMessageSeverityFlagsEXT messageSeverity;
    VkDebugUtilsMessageTypeFlagsEXT messageType;
    PFN_vkDebugUtilsMessengerCallbackEXT pfnUserCallback;
    void* pUserData;
} VkDebugUtilsMessengerCreateInfoEXT;

• sType is a VkStructureType value identifying this structure.
• pNext is NULL or a pointer to a structure extending this structure.
• flags is 0 and is reserved for future use.
• messageSeverity is a bitmask of VkDebugUtilsMessageSeverityFlagBitsEXT specifying which severity of event(s) will cause this callback to be called.
• messageType is a bitmask of VkDebugUtilsMessageTypeFlagBitsEXT specifying which type of event(s) will cause this callback to be called.
• pfnUserCallback is the application callback function to call.
• pUserData is user data to be passed to the callback.

For each VkDebugUtilsMessengerEXT that is created the VkDebugUtilsMessengerCreateInfoEXT::messageSeverity and VkDebugUtilsMessengerCreateInfoEXT::messageType determine when that VkDebugUtilsMessengerCreateInfoEXT::pfnUserCallback is called. The process to determine if the user’s pfnUserCallback is triggered when an event occurs is as follows:

1. The implementation will perform a bitwise AND of the event’s VkDebugUtilsMessageSeverityFlagBitsEXT with the messageSeverity provided during creation of the VkDebugUtilsMessengerEXT object.
   1. If the value is 0, the message is skipped.
2. The implementation will perform bitwise AND of the event’s VkDebugUtilsMessageTypeFlagBitsEXT with the messageType provided during the creation of the VkDebugUtilsMessengerEXT object.
   1. If the value is 0, the message is skipped.
3. The callback will trigger a debug message for the current event

The callback will come directly from the component that detected the event, unless some other layer intercepts the calls for its own purposes (filter them in a different way, log to a system error log, etc.).

An application can receive multiple callbacks if multiple VkDebugUtilsMessengerEXT objects are created. A callback will always be executed in the same thread as the originating Vulkan call.

A callback can be called from multiple threads simultaneously (if the application is making Vulkan calls from multiple threads).