vkCmdPushConstants(3)

C Specification

To update push constants, call:

// Provided by VK_VERSION_1_0
void vkCmdPushConstants(
    VkCommandBuffer                             commandBuffer,
    VkPipelineLayout                            layout,
    VkShaderStageFlags                          stageFlags,
    uint32_t                                    offset,
    uint32_t                                    size,
    const void*                                 pValues);

Parameters

commandBuffer is the command buffer in which the push constant update will be recorded.
layout is the pipeline layout used to program the push constant updates.
stageFlags is a bitmask of VkShaderStageFlagBits specifying the shader stages that will use the push constants in the updated range.
offset is the start offset of the push constant range to update, in units of bytes.
size is the size of the push constant range to update, in units of bytes.
pValues is a pointer to an array of size bytes containing the new push constant values.

Description

When a command buffer begins recording, all push constant values are undefined.

Push constant values can be updated incrementally, causing shader stages in stageFlags to read the new data from pValues for push constants modified by this command, while still reading the previous data for push constants not modified by this command. When a bound pipeline command is issued, the bound pipeline’s layout must be compatible with the layouts used to set the values of all push constants in the pipeline layout’s push constant ranges, as described in Pipeline Layout Compatibility. Binding a pipeline with a layout that is not compatible with the push constant layout does not disturb the push constant values.

Note

As stageFlags needs to include all flags the relevant push constant ranges were created with, any flags that are not supported by the queue family that the VkCommandPool used to allocate commandBuffer was created on are ignored.

Valid Usage

VUID-vkCmdPushConstants-offset-01795
For each byte in the range specified by offset and size and for each shader stage in stageFlags, there must be a push constant range in layout that includes that byte and that stage
VUID-vkCmdPushConstants-offset-01796
For each byte in the range specified by offset and size and for each push constant range that overlaps that byte, stageFlags must include all stages in that push constant range’s VkPushConstantRange::stageFlags
VUID-vkCmdPushConstants-offset-00368
offset must be a multiple of 4
VUID-vkCmdPushConstants-size-00369
size must be a multiple of 4
VUID-vkCmdPushConstants-offset-00370
offset must be less than VkPhysicalDeviceLimits::maxPushConstantsSize
VUID-vkCmdPushConstants-size-00371
size must be less than or equal to VkPhysicalDeviceLimits::maxPushConstantsSize minus offset

Valid Usage (Implicit)

VUID-vkCmdPushConstants-commandBuffer-parameter
commandBuffer must be a valid VkCommandBuffer handle
VUID-vkCmdPushConstants-layout-parameter
layout must be a valid VkPipelineLayout handle
VUID-vkCmdPushConstants-stageFlags-parameter
stageFlags must be a valid combination of VkShaderStageFlagBits values
VUID-vkCmdPushConstants-stageFlags-requiredbitmask
stageFlags must not be 0
VUID-vkCmdPushConstants-pValues-parameter
pValues must be a valid pointer to an array of size bytes
VUID-vkCmdPushConstants-commandBuffer-recording
commandBuffer must be in the recording state
VUID-vkCmdPushConstants-commandBuffer-cmdpool
The VkCommandPool that commandBuffer was allocated from must support graphics, or compute operations
VUID-vkCmdPushConstants-size-arraylength
size must be greater than 0
VUID-vkCmdPushConstants-commonparent
Both of commandBuffer, and layout must have been created, allocated, or retrieved from the same VkDevice

Host Synchronization

Host access to commandBuffer must be externally synchronized
Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized