The Specification describes Vulkan commands as functions or procedures using C99 syntax. Language bindings for other languages such as C++ and JavaScript may allow for stricter parameter passing, or object-oriented interfaces.
Vulkan uses the standard C types for the base type of scalar parameters
(e.g. types from stdint.h), with exceptions described below, or elsewhere
in the text when appropriate:
VkBool32 represents boolean True and False values, since C does
not have a sufficiently portable built-in boolean type:
typedef uint32_t VkBool32;
VK_TRUE represents a boolean True (integer 1) value, and
VK_FALSE a boolean False (integer 0) value.
All values returned from a Vulkan implementation in a VkBool32 will
be either VK_TRUE or VK_FALSE.
Applications must not pass any other values than VK_TRUE or
VK_FALSE into a Vulkan implementation where a VkBool32 is
expected.
VkDeviceSize represents device memory size and offset values:
typedef uint64_t VkDeviceSize;
Commands that create Vulkan objects are of the form vkCreate* and take
Vk*CreateInfo structures with the parameters needed to create the
object.
These Vulkan objects are destroyed with commands of the form
vkDestroy*.
The last in-parameter to each command that creates or destroys a Vulkan
object is pAllocator.
The pAllocator parameter can be set to a non-NULL value such that
allocations for the given object are delegated to an application provided
callback; refer to the Memory Allocation chapter for
further details.
Commands that allocate Vulkan objects owned by pool objects are of the form
vkAllocate*, and take Vk*AllocateInfo structures.
These Vulkan objects are freed with commands of the form vkFree*.
These objects do not take allocators; if host memory is needed, they will
use the allocator that was specified when their parent pool was created.
Commands are recorded into a command buffer by calling API commands of the
form vkCmd*.
Each such command may have different restrictions on where it can be used:
in a primary and/or secondary command buffer, inside and/or outside a render
pass, and in one or more of the supported queue types.
These restrictions are documented together with the definition of each such
command.
The duration of a Vulkan command refers to the interval between calling the command and its return to the caller.
Information is retrieved from the implementation with commands of the form
vkGet* and vkEnumerate*.
Unless otherwise specified for an individual command, the results are invariant; that is, they will remain unchanged when retrieved again by calling the same command with the same parameters, so long as those parameters themselves all remain valid.