pushConstantStages

Push constants in graphics APIs like Vulkan provide a mechanism for developers to pass small amounts of data to shaders on a per-draw-call basis. The pushConstantStages member of a Vulkan pipeline layout specifies which shader stages can access the data provided by push constants. This member is a bitmask that can be set to any combination of the VkShaderStageFlagBits enum values. These flags include Vertex, Tessellation Control, Tessellation Evaluation, Geometry, Fragment, and Compute shader stages. By specifying these stages, the pipeline layout defines the scope of visibility for the push constant data, ensuring that only intended shader stages receive and can utilize this information. This granular control is crucial for performance optimization, as it allows for frequent updates of small, dynamic parameters without the overhead associated with binding uniform buffer objects. When creating a VkPipelineLayout object, the pushConstantStages is a critical component of the VkPushConstantRange structure, which also defines the offset and size of the push constant data within the shader.