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D3D12DDI_RAYTRACING_GEOMETRY_TRIANGLES_DESC_0054 structure (d3d12umddi.h)

  • Article

Describes a ray tracing triangle geometry.

Syntax

typedef struct D3D12DDI_RAYTRACING_GEOMETRY_TRIANGLES_DESC_0054 {
  D3D12DDI_GPU_VIRTUAL_ADDRESS            ColumnMajorTransform3x4;
  DXGI_FORMAT                             IndexFormat;
  DXGI_FORMAT                             VertexFormat;
  UINT                                    IndexCount;
  UINT                                    VertexCount;
  D3D12DDI_GPU_VIRTUAL_ADDRESS            IndexBuffer;
  D3D12DDI_GPU_VIRTUAL_ADDRESS_AND_STRIDE VertexBuffer;
} D3D12DDI_RAYTRACING_GEOMETRY_TRIANGLES_DESC_0054;

Members

ColumnMajorTransform3x4

Address of a 3x4 affine transform matrix in row major layout to be applied to the vertices in the VertexBuffer during an acceleration structure build. The contents of VertexBuffer are not modified. If a 2D vertex format is used, the transformation is applied with the third vertex component assumed to be zero.

If ColumnMajorTransform3x4 is NULL the vertices will not be transformed. Using ColumnMajorTransform3x4 may result in increased computation and/or memory requirements for the acceleration structure build.

The memory pointed to must be in resource state D3D12DDI_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE.

IndexFormat

A DXGI_FORMAT, representing the format of the indices in IndexBuffer. This value must be one of the following:

  • DXGI_FORMAT_UNKNOWN (when IndexBuffer is NULL)
  • DXGI_FORMAT_R32_UINT
  • DXGI_FORMAT_R16_UINT

VertexFormat

A DXGI_FORMAT, representing the format of the vertices (positions) in VertexBuffer. This value must be one of the following:

  • DXGI_FORMAT_R32G32_FLOAT (third component assumed 0)
  • DXGI_FORMAT_R32G32B32_FLOAT
  • DXGI_FORMAT_R16G16_FLOAT (third component assumed 0)
  • DXGI_FORMAT_R16G16B16A16_FLOAT

IndexCount

Number of indices in IndexBuffer. Must be 0 if IndexBuffer is NULL.

VertexCount

Number of vertices (positions) in VertexBuffer.

IndexBuffer

Array of vertex indices. If NULL, triangles are non-indexed. The address must be aligned to the size of IndexFormat.

The memory pointed to must be in resource state D3D12DDI_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE.

VertexBuffer

Array of vertices including a stride. The alignment on the address and stride must be a multiple of the component size, meaning, 4 bytes for formats with 32-bit components and 2 bytes for formats with 16-bit components. There is no constraint on the stride (whereas there is a limit for graphics), other than that the bottom 32-bits of the value are all that are used. This means that the field is UINT64 purely to make neighboring fields align cleanly and obviously everywhere. Each vertex position is expected to be at the start address of the stride range and any excess space is ignored by acceleration structure builds. This excess space might contain other app data such as vertex attributes, which the app is responsible for manually fetching in shaders, whether it is interleaved in vertex buffers or elsewhere.

The memory pointed to must be in resource state D3D12DDI_RESOURCE_STATE_NON_PIXEL_SHADER_RESOURCE.

Remarks

The geometry pointed to by this structure is always in triangle list from (indexed or non-indexed form). Strips are not supported.

Requirements

Requirement Value
Minimum supported client Windows 10, version 1809
Header d3d12umddi.h