C Specification

To record an indexed draw, call:

void vkCmdDrawIndexed(
    VkCommandBuffer                             commandBuffer,
    uint32_t                                    indexCount,
    uint32_t                                    instanceCount,
    uint32_t                                    firstIndex,
    int32_t                                     vertexOffset,
    uint32_t                                    firstInstance);

Parameters

  • commandBuffer is the command buffer into which the command is recorded.

  • indexCount is the number of vertices to draw.

  • instanceCount is the number of instances to draw.

  • firstIndex is the base index within the index buffer.

  • vertexOffset is the value added to the vertex index before indexing into the vertex buffer.

  • firstInstance is the instance ID of the first instance to draw.

Description

When the command is executed, primitives are assembled using the current primitive topology and indexCount vertices whose indices are retrieved from the index buffer. The index buffer is treated as an array of tightly packed unsigned integers of size defined by the vkCmdBindIndexBuffer::indexType parameter with which the buffer was bound.

The first vertex index is at an offset of firstIndex * indexSize + offset within the currently bound index buffer, where offset is the offset specified by vkCmdBindIndexBuffer and indexSize is the byte size of the type specified by indexType. Subsequent index values are retrieved from consecutive locations in the index buffer. Indices are first compared to the primitive restart value, then zero extended to 32 bits (if the indexType is VK_INDEX_TYPE_UINT16) and have vertexOffset added to them, before being supplied as the vertexIndex value.

The primitives are drawn instanceCount times with instanceIndex starting with firstInstance and increasing sequentially for each instance. The assembled primitives execute the currently bound graphics pipeline.

Valid Usage
  • The current render pass must be compatible with the renderPass member of the VkGraphicsPipelineCreateInfo structure specified when creating the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS.

  • The subpass index of the current render pass must be equal to the subpass member of the VkGraphicsPipelineCreateInfo structure specified when creating the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS.

  • For each set n that is statically used by the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS, a descriptor set must have been bound to n at VK_PIPELINE_BIND_POINT_GRAPHICS, with a VkPipelineLayout that is compatible for set n, with the VkPipelineLayout used to create the current VkPipeline, as described in [descriptorsets-compatibility]

  • For each push constant that is statically used by the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS, a push constant value must have been set for VK_PIPELINE_BIND_POINT_GRAPHICS, with a VkPipelineLayout that is compatible for push constants, with the VkPipelineLayout used to create the current VkPipeline, as described in [descriptorsets-compatibility]

  • Descriptors in each bound descriptor set, specified via vkCmdBindDescriptorSets, must be valid if they are statically used by the currently bound VkPipeline object, specified via vkCmdBindPipeline

  • All vertex input bindings accessed via vertex input variables declared in the vertex shader entry point’s interface must have valid buffers bound

  • For a given vertex buffer binding, any attribute data fetched must be entirely contained within the corresponding vertex buffer binding, as described in [fxvertex-input]

  • A valid graphics pipeline must be bound to the current command buffer with VK_PIPELINE_BIND_POINT_GRAPHICS

  • If the VkPipeline object currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS requires any dynamic state, that state must have been set on the current command buffer

  • (indexSize * (firstIndex + indexCount) + offset) must be less than or equal to the size of the currently bound index buffer, with indexSize being based on the type specified by indexType, where the index buffer, indexType, and offset are specified via vkCmdBindIndexBuffer

  • Every input attachment used by the current subpass must be bound to the pipeline via a descriptor set

  • If any VkSampler object that is accessed from a shader by the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS uses unnormalized coordinates, it must not be used to sample from any VkImage with a VkImageView of the type VK_IMAGE_VIEW_TYPE_3D, VK_IMAGE_VIEW_TYPE_CUBE, VK_IMAGE_VIEW_TYPE_1D_ARRAY, VK_IMAGE_VIEW_TYPE_2D_ARRAY or VK_IMAGE_VIEW_TYPE_CUBE_ARRAY, in any shader stage

  • If any VkSampler object that is accessed from a shader by the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS uses unnormalized coordinates, it must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions with ImplicitLod, Dref or Proj in their name, in any shader stage

  • If any VkSampler object that is accessed from a shader by the VkPipeline currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS uses unnormalized coordinates, it must not be used with any of the SPIR-V OpImageSample* or OpImageSparseSample* instructions that includes a LOD bias or any offset values, in any shader stage

  • If the robust buffer access feature is not enabled, and any shader stage in the VkPipeline object currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS accesses a uniform buffer, it must not access values outside of the range of that buffer specified in the currently bound descriptor set

  • If the robust buffer access feature is not enabled, and any shader stage in the VkPipeline object currently bound to VK_PIPELINE_BIND_POINT_GRAPHICS accesses a storage buffer, it must not access values outside of the range of that buffer specified in the currently bound descriptor set

  • Any VkImageView being sampled with VK_FILTER_LINEAR as a result of this command must be of a format which supports linear filtering, as specified by the VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT flag in VkFormatProperties::linearTilingFeatures (for a linear image) or VkFormatProperties::optimalTilingFeatures(for an optimally tiled image) returned by vkGetPhysicalDeviceFormatProperties

Valid Usage (Implicit)
  • commandBuffer must be a valid VkCommandBuffer handle

  • commandBuffer must be in the recording state

  • The VkCommandPool that commandBuffer was allocated from must support graphics operations

  • This command must only be called inside of a render pass instance

Host Synchronization
  • Host access to commandBuffer must be externally synchronized

  • Host access to the VkCommandPool that commandBuffer was allocated from must be externally synchronized

Command Properties
Command Buffer Levels Render Pass Scope Supported Queue Types Pipeline Type

Primary
Secondary

Inside

Graphics

Graphics

See Also

Document Notes

For more information, see the Vulkan Specification at URL

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification,not directly.

Copyright (c) 2014-2016 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.