VkPushConstantRange

VkPushConstantRange is a structure defined in the Vulkan graphics API. It is used to describe a contiguous range of memory that can be updated by the CPU and read by shaders within a graphics pipeline. This memory is referred to as push constants. Push constants provide a mechanism for frequently changing, small amounts of data to be passed to shaders without the overhead of uniform buffer objects.

The VkPushConstantRange structure contains three members: stageFlags, offset, and size. The stageFlags member specifies which shader stages (e.g., vertex, fragment, compute) can access this push constant range. The offset member defines the starting byte offset of the push constant range within the overall push constant buffer. The size member indicates the size in bytes of the push constant range.

When using push constants, developers define one or more VkPushConstantRange structures to outline the layout of the push constant data. This layout is then provided to the Vulkan pipeline creation process. During rendering, the application can update the contents of the push constant buffer, and these updates will be visible to the specified shader stages. The maximum size of the push constant buffer is determined by the implementation and can be queried using vkGetPhysicalDeviceProperties. Push constants are intended for small, frequently changing data, and their use should be balanced with other data transfer mechanisms like uniform buffers and storage buffers.