C Specification

Function pointers for all Vulkan commands can be obtained by calling:

// Provided by VK_VERSION_1_0
PFN_vkVoidFunction vkGetInstanceProcAddr(
    VkInstance                                  instance,
    const char*                                 pName);

Parameters

  • instance is the instance that the function pointer will be compatible with, or NULL for commands not dependent on any instance.

  • pName is the name of the command to obtain.

Description

vkGetInstanceProcAddr itself is obtained in a platform- and loader- specific manner. Typically, the loader library will export this command as a function symbol, so applications can link against the loader library, or load it dynamically and look up the symbol using platform-specific APIs.

The table below defines the various use cases for vkGetInstanceProcAddr and expected return value (“fp” is “function pointer”) for each case. A valid returned function pointer (“fp”) must not be NULL.

The returned function pointer is of type PFN_vkVoidFunction, and must be cast to the type of the command being queried before use.

Table 1. vkGetInstanceProcAddr behavior
instance pName return value

*1

NULL

undefined

invalid non-NULL instance

*1

undefined

NULL

global command2

fp

NULL

vkGetInstanceProcAddr

fp5

instance

vkGetInstanceProcAddr

fp

instance

core dispatchable command

fp3

instance

enabled instance extension dispatchable command for instance

fp3

instance

available device extension4 dispatchable command for instance

fp3

any other case, not covered above

NULL
1

"*" means any representable value for the parameter (including valid values, invalid values, and NULL).

2

The global commands are: vkEnumerateInstanceVersion, vkEnumerateInstanceExtensionProperties, vkEnumerateInstanceLayerProperties, and vkCreateInstance. Dispatchable commands are all other commands which are not global.

3

The returned function pointer must only be called with a dispatchable object (the first parameter) that is instance or a child of instance, e.g. VkInstance, VkPhysicalDevice, VkDevice, VkQueue, or VkCommandBuffer.

4

An “available device extension” is a device extension supported by any physical device enumerated by instance.

5

Starting with Vulkan 1.2, vkGetInstanceProcAddr can resolve itself with a NULL instance pointer.

Valid Usage (Implicit)

  • VUID-vkGetInstanceProcAddr-instance-parameter
    If instance is not NULL, instance must be a valid VkInstance handle

  • VUID-vkGetInstanceProcAddr-pName-parameter
    pName must be a null-terminated UTF-8 string

See Also

PFN_vkVoidFunction, VK_VERSION_1_0, VkInstance

Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2024 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0