Vulkan-Docs/chapters/VK_NVX_device_generated_com.../indirectcommands.txt

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[[indirectmdslayout]]
== Indirect Commands Layout
[open,refpage='VkIndirectCommandsLayoutNVX',desc='Opaque handle to an indirect commands layout object',type='handles']
--
The device-side command generation happens through an iterative processing
of an atomic sequence comprised of command tokens, which are represented by:
include::../../api/handles/VkIndirectCommandsLayoutNVX.txt[]
--
=== Tokenized Command Processing
The processing is in principle illustrated below:
[source,c]
---------------------------------------------------
void cmdProcessSequence(cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, s)
{
for (c = 0; c < indirectCommandsLayout.tokenCount; c++)
{
indirectCommandsLayout.pTokens[c].command (cmd, objectTable, pIndirectCommandsTokens[c], s);
}
}
void cmdProcessAllSequences(cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, sequencesCount)
{
for (s = 0; s < sequencesCount; s++)
{
cmdProcessSequence(cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, s);
}
}
---------------------------------------------------
The processing of each sequence is considered stateless, therefore all state
changes must: occur prior work provoking commands within the sequence.
A single sequence is either strictly targeting
ename:VK_PIPELINE_BIND_POINT_GRAPHICS or
ename:VK_PIPELINE_BIND_POINT_COMPUTE.
The primary input data for each token is provided through sname:VkBuffer
content at command generation time using flink:vkCmdProcessCommandsNVX,
however some functional arguments, for example binding sets, are specified
at layout creation time.
The input size is different for each token.
[open,refpage='VkIndirectCommandsTokenTypeNVX',desc='Enum specifying',type='enums']
--
Possible values of those elements of the
slink:VkIndirectCommandsLayoutCreateInfoNVX::pname:pTokens array which
specify command tokens (other elements of the array specify command
parameters) are:
include::../../api/enums/VkIndirectCommandsTokenTypeNVX.txt[]
.Supported indirect command tokens
[width="80%",cols="67%,33%",options="header",align="center"]
|====
|Token type | Equivalent command
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_PIPELINE_NVX | fname:vkCmdBindPipeline
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DESCRIPTOR_SET_NVX | fname:vkCmdBindDescriptorSets
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_INDEX_BUFFER_NVX | fname:vkCmdBindIndexBuffer
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_VERTEX_BUFFER_NVX | fname:vkCmdBindVertexBuffers
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_PUSH_CONSTANT_NVX | fname:vkCmdPushConstants
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_INDEXED_NVX | fname:vkCmdDrawIndexedIndirect
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_NVX | fname:vkCmdDrawIndirect
|ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DISPATCH_NVX | fname:vkCmdDispatchIndirect
|====
--
[open,refpage='VkIndirectCommandsLayoutTokenNVX',desc='Struct specifying the details of an indirect command layout token',type='structs']
--
The sname:VkIndirectCommandsLayoutTokenNVX structure specifies details to
the function arguments that need to be known at layout creation time:
include::../../api/structs/VkIndirectCommandsLayoutTokenNVX.txt[]
* pname:type specifies the token command type.
* pname:bindingUnit has a different meaning depending on the type, please
refer pseudo code further down for details.
* pname:dynamicCount has a different meaning depending on the type, please
refer pseudo code further down for details.
* pname:divisor defines the rate at which the input data buffers are
accessed.
.Valid Usage
****
* [[VUID-VkIndirectCommandsLayoutTokenNVX-bindingUnit-01342]]
pname:bindingUnit must: stay within device supported limits for the
appropriate commands.
* [[VUID-VkIndirectCommandsLayoutTokenNVX-dynamicCount-01343]]
pname:dynamicCount must: stay within device supported limits for the
appropriate commands.
* [[VUID-VkIndirectCommandsLayoutTokenNVX-divisor-01344]]
pname:divisor must: be greater than `0` and a power of two.
****
include::../../validity/structs/VkIndirectCommandsLayoutTokenNVX.txt[]
--
[open,refpage='VkIndirectCommandsTokenNVX',desc='Structure specifying parameters for the reservation of command buffer space',type='structs']
--
The sname:VkIndirectCommandsTokenNVX structure specifies the input data for
a token at processing time.
include::../../api/structs/VkIndirectCommandsTokenNVX.txt[]
* pname:tokenType specifies the token command type.
* pname:buffer specifies the slink:VkBuffer storing the functional
arguments for each squence.
These argumetns can be written by the device.
* pname:offset specified an offset into pname:buffer where the arguments
start.
.Valid Usage
****
* [[VUID-VkIndirectCommandsTokenNVX-buffer-01345]]
The pname:buffer's usage flag must: have the
ename:VK_BUFFER_USAGE_INDIRECT_BUFFER_BIT bit set.
* [[VUID-VkIndirectCommandsTokenNVX-offset-01346]]
The pname:offset must: be aligned to
sname:VkDeviceGeneratedCommandsLimitsNVX::pname:minCommandsTokenBufferOffsetAlignment.
****
include::../../validity/structs/VkIndirectCommandsTokenNVX.txt[]
--
The following code provides detailed information on how an individual
sequence is processed:
[source,c]
---------------------------------------------------
void cmdProcessSequence(cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, s)
{
for (uint32_t c = 0; c < indirectCommandsLayout.tokenCount; c++){
input = pIndirectCommandsTokens[c];
i = s / indirectCommandsLayout.pTokens[c].divisor;
switch(input.type){
VK_INDIRECT_COMMANDS_TOKEN_TYPE_PIPELINE_NVX:
size_t stride = sizeof(uint32_t);
uint32_t* data = input.buffer.pointer( input.offset + stride * i );
uint32_t object = data[0];
vkCmdBindPipeline(cmd, indirectCommandsLayout.pipelineBindPoint,
objectTable.pipelines[ object ].pipeline);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_DESCRIPTOR_SET_NVX:
size_t stride = sizeof(uint32_t) + sizeof(uint32_t) * indirectCommandsLayout.pTokens[c].dynamicCount;
uint32_t* data = input.buffer.pointer( input.offset + stride * i);
uint32_t object = data[0];
vkCmdBindDescriptorSets(cmd, indirectCommandsLayout.pipelineBindPoint,
objectTable.descriptorsets[ object ].layout,
indirectCommandsLayout.pTokens[ c ].bindingUnit,
1, &objectTable.descriptorsets[ object ].descriptorSet,
indirectCommandsLayout.pTokens[ c ].dynamicCount, data + 1);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_PUSH_CONSTANT_NVX:
size_t stride = sizeof(uint32_t) + indirectCommandsLayout.pTokens[c].dynamicCount;
uint32_t* data = input.buffer.pointer( input.offset + stride * i );
uint32_t object = data[0];
vkCmdPushConstants(cmd,
objectTable.pushconstants[ object ].layout,
objectTable.pushconstants[ object ].stageFlags,
indirectCommandsLayout.pTokens[ c ].bindingUnit, indirectCommandsLayout.pTokens[c].dynamicCount, data + 1);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_INDEX_BUFFER_NVX:
size_t s tride = sizeof(uint32_t) + sizeof(uint32_t) * indirectCommandsLayout.pTokens[c].dynamicCount;
uint32_t* data = input.buffer.pointer( input.offset + stride * i );
uint32_t object = data[0];
vkCmdBindIndexBuffer(cmd,
objectTable.vertexbuffers[ object ].buffer,
indirectCommandsLayout.pTokens[ c ].dynamicCount ? data[1] : 0,
objectTable.vertexbuffers[ object ].indexType);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_VERTEX_BUFFER_NVX:
size_t stride = sizeof(uint32_t) + sizeof(uint32_t) * indirectCommandsLayout.pTokens[c].dynamicCount;
uint32_t* data = input.buffer.pointer( input.offset + stride * i );
uint32_t object = data[0];
vkCmdBindVertexBuffers(cmd,
indirectCommandsLayout.pTokens[ c ].bindingUnit, 1,
&objectTable.vertexbuffers[ object ].buffer,
indirectCommandsLayout.pTokens[ c ].dynamicCount ? data + 1 : {0}); // device size handled as uint32_t
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_INDEXED_NVX:
vkCmdDrawIndexedIndirect(cmd,
input.buffer,
sizeof(VkDrawIndexedIndirectCommand) * i + input.offset, 1, 0);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_NVX:
vkCmdDrawIndirect(cmd,
input.buffer,
sizeof(VkDrawIndirectCommand) * i + input.offset, 1, 0);
break;
VK_INDIRECT_COMMANDS_TOKEN_TYPE_DISPATCH_NVX:
vkCmdDispatchIndirect(cmd,
input.buffer,
sizeof(VkDispatchIndirectCommand) * i + input.offset);
break;
}
}
}
---------------------------------------------------
=== Creation and Deletion
[open,refpage='vkCreateIndirectCommandsLayoutNVX',desc='Create an indirect command layout object',type='protos']
--
Indirect command layouts are created by:
include::../../api/protos/vkCreateIndirectCommandsLayoutNVX.txt[]
* pname:device is the logical device that creates the indirect command
layout.
* pname:pCreateInfo is a pointer to an instance of the
sname:VkIndirectCommandsLayoutCreateInfoNVX structure containing
parameters affecting creation of the indirect command layout.
* pname:pAllocator controls host memory allocation as described in the
<<memory-allocation, Memory Allocation>> chapter.
* pname:pIndirectCommandsLayout points to a
sname:VkIndirectCommandsLayoutNVX handle in which the resulting indirect
command layout is returned.
include::../../validity/protos/vkCreateIndirectCommandsLayoutNVX.txt[]
--
[open,refpage='VkIndirectCommandsLayoutCreateInfoNVX',desc='Structure specifying the parameters of a newly created indirect commands layout object',type='structs']
--
The sname:VkIndirectCommandsLayoutCreateInfoNVX structure is defined as:
include::../../api/structs/VkIndirectCommandsLayoutCreateInfoNVX.txt[]
* pname:sType is the type of this structure.
* pname:pNext is `NULL` or a pointer to an extension-specific structure.
* pname:pipelineBindPoint is the elink:VkPipelineBindPoint that this
layout targets.
* pname:flags is a bitmask of
elink:VkIndirectCommandsLayoutUsageFlagBitsNVX specifying usage hints of
this layout.
* pname:tokenCount is the length of the individual command sequnce.
* pname:pTokens is an array describing each command token in detail.
See elink:VkIndirectCommandsTokenTypeNVX and
slink:VkIndirectCommandsLayoutTokenNVX below for details.
The following code illustrates some of the key flags:
[source,c]
---------------------------------------------------
void cmdProcessAllSequences(cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, sequencesCount, indexbuffer, indexbufferoffset)
{
for (s = 0; s < sequencesCount; s++)
{
sequence = s;
if (indirectCommandsLayout.flags & VK_INDIRECT_COMMANDS_LAYOUT_USAGE_UNORDERED_SEQUENCES_BIT_NVX) {
sequence = incoherent_implementation_dependent_permutation[ sequence ];
}
if (indirectCommandsLayout.flags & VK_INDIRECT_COMMANDS_LAYOUT_USAGE_INDEXED_SEQUENCES_BIT_NVX) {
sequence = indexbuffer.load_uint32( sequence * sizeof(uint32_t) + indexbufferoffset);
}
cmdProcessSequence( cmd, objectTable, indirectCommandsLayout, pIndirectCommandsTokens, sequence );
}
}
---------------------------------------------------
.Valid Usage
****
* [[VUID-VkIndirectCommandsLayoutCreateInfoNVX-tokenCount-01347]]
pname:tokenCount must: be greater than `0` and below
sname:VkDeviceGeneratedCommandsLimitsNVX::pname:maxIndirectCommandsLayoutTokenCount
* [[VUID-VkIndirectCommandsLayoutCreateInfoNVX-computeBindingPointSupport-01348]]
If the
sname:VkDeviceGeneratedCommandsFeaturesNVX::pname:computeBindingPointSupport
feature is not enabled, then pname:pipelineBindPoint must: not be
ename:VK_PIPELINE_BIND_POINT_COMPUTE
* [[VUID-VkIndirectCommandsLayoutCreateInfoNVX-pTokens-01349]]
If pname:pTokens contains an entry of
ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_PIPELINE_NVX it must: be the first
element of the array and there must: be only a single element of such
token type.
* [[VUID-VkIndirectCommandsLayoutCreateInfoNVX-pTokens-01350]]
All state binding tokens in pname:pTokens must: occur prior work
provoking tokens (ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_NVX,
ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DRAW_INDEXED_NVX,
ename:VK_INDIRECT_COMMANDS_TOKEN_TYPE_DISPATCH_NVX).
* [[VUID-VkIndirectCommandsLayoutCreateInfoNVX-pTokens-01351]]
The content of pname:pTokens must: include one single work provoking
token that is compatible with the pname:pipelineBindPoint.
****
include::../../validity/structs/VkIndirectCommandsLayoutCreateInfoNVX.txt[]
--
[open,refpage='VkIndirectCommandsLayoutUsageFlagBitsNVX',desc='Bitmask specifying allowed usage of an indirect commands layout',type='enums']
--
Bits which can: be set in
slink:VkIndirectCommandsLayoutCreateInfoNVX::pname:flags, specifying usage
hints of an indirect command layout, are:
include::../../api/enums/VkIndirectCommandsLayoutUsageFlagBitsNVX.txt[]
* ename:VK_INDIRECT_COMMANDS_LAYOUT_USAGE_UNORDERED_SEQUENCES_BIT_NVX
specifies that the processing of sequences can: happen at an
implementation-dependent order, which is not guaranteed to be coherent
across multiple invocations.
* ename:VK_INDIRECT_COMMANDS_LAYOUT_USAGE_SPARSE_SEQUENCES_BIT_NVX
specifies that there is likely a high difference between allocated
number of sequences and actually used.
* ename:VK_INDIRECT_COMMANDS_LAYOUT_USAGE_EMPTY_EXECUTIONS_BIT_NVX
specifies that there are likely many draw or dispatch calls that are
zero-sized (zero grid dimension, no primitives to render).
* ename:VK_INDIRECT_COMMANDS_LAYOUT_USAGE_INDEXED_SEQUENCES_BIT_NVX
specifies that the input data for the sequences is not implicitly
indexed from 0..sequencesUsed but a user provided sname:VkBuffer
encoding the index is provided.
--
[open,refpage='VkIndirectCommandsLayoutUsageFlagsNVX',desc='Bitmask of VkIndirectCommandsLayoutUsageFlagBitsNVX',type='flags']
--
include::../../api/flags/VkIndirectCommandsLayoutUsageFlagsNVX.txt[]
tname:VkIndirectCommandsLayoutUsageFlagsNVX is a bitmask type for setting a
mask of zero or more elink:VkIndirectCommandsLayoutUsageFlagBitsNVX.
--
[open,refpage='vkDestroyIndirectCommandsLayoutNVX',desc='Destroy an object table',type='protos']
--
Indirect command layouts are destroyed by:
include::../../api/protos/vkDestroyIndirectCommandsLayoutNVX.txt[]
* pname:device is the logical device that destroys the layout.
* pname:indirectCommandsLayout is the table to destroy.
* pname:pAllocator controls host memory allocation as described in the
<<memory-allocation, Memory Allocation>> chapter.
.Valid Usage
****
* [[VUID-vkDestroyIndirectCommandsLayoutNVX-indirectCommandsLayout-01352]]
All submitted commands that refer to pname:indirectCommandsLayout must:
have completed execution
* [[VUID-vkDestroyIndirectCommandsLayoutNVX-objectTable-01353]]
If sname:VkAllocationCallbacks were provided when pname:objectTable was
created, a compatible set of callbacks must: be provided here
* [[VUID-vkDestroyIndirectCommandsLayoutNVX-objectTable-01354]]
If no sname:VkAllocationCallbacks were provided when pname:objectTable
was created, pname:pAllocator must: be `NULL`
****
include::../../validity/protos/vkDestroyIndirectCommandsLayoutNVX.txt[]
--