VkDrawIndexedIndirect

VkDrawIndexedIndirect is a Vulkan graphics API command. It is used to issue draw calls for indexed geometry in an indirect manner. This means that the parameters for the draw call are not provided directly by the application code but are instead read from a buffer in GPU memory. This allows for a more efficient way to render multiple sets of indexed geometry, especially when the number of draw calls is dynamic or determined by the GPU itself.

The command takes a pointer to a VkBuffer and an offset within that buffer. The buffer must contain a sequence of VkDrawIndexedIndirectCommand structures. Each structure specifies the index count, instance count, first index, vertex offset, and first instance for a single draw call. The GPU reads these commands sequentially from the buffer and executes the corresponding indexed draw operations.

Using VkDrawIndexedIndirect can significantly reduce CPU overhead, as the application only needs to issue a single command to the GPU, regardless of how many individual draw calls are contained within the indirect buffer. This is particularly beneficial in scenarios like rendering particle systems, instanced objects with varying parameters, or when performing complex culling operations on the GPU. The indirect draw mechanism empowers developers to offload more rendering logic to the GPU, leading to improved performance and scalability.