# MTLRenderPassSampleBufferAttachmentDescriptor A description of where to store GPU counter information at the start and end of a render pass. ``` class MTLRenderPassSampleBufferAttachmentDescriptor ``` ## Topics ### Configuring the sample buffer attachment [`sampleBuffer`](/documentation/Metal/MTLRenderPassSampleBufferAttachmentDescriptor/sampleBuffer) A specialized memory buffer that the GPU uses to store its counter data during the render pass. [`startOfVertexSampleIndex`](/documentation/Metal/MTLRenderPassSampleBufferAttachmentDescriptor/startOfVertexSampleIndex) The index the Metal device object should use to store GPU counters when starting the render pass’s vertex stage. [`endOfVertexSampleIndex`](/documentation/Metal/MTLRenderPassSampleBufferAttachmentDescriptor/endOfVertexSampleIndex) The index the Metal device object should use to store GPU counters when ending the render pass’s vertex stage. [`startOfFragmentSampleIndex`](/documentation/Metal/MTLRenderPassSampleBufferAttachmentDescriptor/startOfFragmentSampleIndex) The index the Metal device object should use to store GPU counters when starting the render pass’s fragment stage. [`endOfFragmentSampleIndex`](/documentation/Metal/MTLRenderPassSampleBufferAttachmentDescriptor/endOfFragmentSampleIndex) The index the Metal device object should use to store GPU counters when ending the render pass’s fragment stage. --- 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)