# drawIndexedPrimitives(primitiveType:indexType:indexBuffer:indexBufferLength:indirectBuffer:) Encodes a draw command that renders multiple instances of a geometric primitive with indexed vertices and indirect arguments. ``` func drawIndexedPrimitives(primitiveType: MTLPrimitiveType, indexType: MTLIndexType, indexBuffer: MTLGPUAddress, indexBufferLength: Int, indirectBuffer: MTLGPUAddress) ``` ## Parameters `primitiveType` A [`MTLPrimitiveType`](/documentation/Metal/MTLPrimitiveType) representing how the command interprets vertex argument data. `indexType` A [`MTLIndexType`](/documentation/Metal/MTLIndexType) instance that represents the index format. `indexBuffer` GPUAddress of a [`MTLBuffer`](/documentation/Metal/MTLBuffer) instance that contains `indexCount` indices of `indexType` format. You are responsible for ensuring this address is aligned to 2 bytes if the `indexType` format is [`MTLIndexType.uint16`](/documentation/Metal/MTLIndexType/uint16), and aligned to 4 bytes if the format is [`MTLIndexType.uint32`](/documentation/Metal/MTLIndexType/uint32). `indexBufferLength` An integer that represents the length of `indexBuffer`, in bytes. You are responsible for ensuring this this size is a multiple of 2 if the `indexType` format is [`MTLIndexType.uint16`](/documentation/Metal/MTLIndexType/uint16), and a multiple of 4 if the format is [`MTLIndexType.uint32`](/documentation/Metal/MTLIndexType/uint32). If this draw call causes Metal to read indices at or beyond the `indexBufferLength`, Metal continues to execute them assigning a value of `0` to the `vertex_id` attribute. `indirectBuffer` GPUAddress of an [`MTLBuffer`](/documentation/Metal/MTLBuffer) instance with data that matches the layout of the [`MTLDrawIndexedPrimitivesIndirectArguments`](/documentation/Metal/MTLDrawIndexedPrimitivesIndirectArguments) structure. This address requires 4-byte alignment. ## Discussion When you use this function, Metal reads the parameters to the draw command from an [`MTLBuffer`](/documentation/Metal/MTLBuffer) instance, allowing you to implement a GPU-driven workflow where a compute pipeline state determines the draw arguments. Because this is an indexed draw call, Metal interprets the contents of the indirect buffer to match the layout of struct [`MTLDrawIndexedPrimitivesIndirectArguments`](/documentation/Metal/MTLDrawIndexedPrimitivesIndirectArguments), which includes `indexStart` and `indexCount` members, denoting a range within the index buffer you provide in the `indexBuffer` parameter. The range of indices within the `indexBuffer` form the primitives Metal draws. Metal imposes some restrictions on the index buffer’s address, which needs to be 2- or 4-byte aligned, and its length in bytes, which needs to be a multiple of 2 or 4, depending on whether the format of the index is [`MTLIndexType.uint16`](/documentation/Metal/MTLIndexType/uint16) or [`MTLIndexType.uint32`](/documentation/Metal/MTLIndexType/uint32). Similarly, you are responsible for ensuring the indirect buffer’s address has 4-byte alignment. Use an instance of [`MTLResidencySet`](/documentation/Metal/MTLResidencySet) to mark residency of the indirect buffer that the `indirectBuffer` parameter references, and of the index buffer the `indexBuffer` parameter references. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)